The sternum develops from two primordial meso- blastic bands, which make their appearance around the 6th week of gestation and subsequently fuse on the midline in about the 9th week of gestation, giving rise to a median plate of hyaline cartilage. Within this cartilaginous plate, a variable number of ossification centers develop and later coalesce to form the adult sternum. The first center, usually unique, appears in the manubrium at about the 25th week of gestation, and others follow in the body at about 1-month inter- vals with a craniocaudal progression (McCormick and Nichols 1981). Two foci of ossification, one either side of the midline, are identifiable for each segment.
Fusion occurs at the midline between the two foci, starting from the lowest point and progressing up- ward through different levels. Ossification between segments in the lower portion of the sternal body oc- curs soon after puberty, whereas ossification be- tween segments in the upper portion occurs between puberty and the third decade. The manubriosternal junction usually remains unossified until adulthood, and ossification between the body and xiphoid pro- cess usually occurs at approximately 40 years of age.
Around the 9th week of gestation, and before ossi- fication of the vertebrae begins, the primary ossifica- tion centers for the ribs make their appearance near the angles of the ribs (in the formed rib the angle is located just anterior to the tubercle). From the an- gles, ossification extends forward along the shafts, which are completely ossified by approximately the 16th fetal week. The anterior ends of the ribs remain cartilaginous, giving rise to the costal cartilages. Sec- ondary ossification centers develop in the head and tubercle of the 1st through 10th ribs during puberty and fuse with the shaft at the age of approximately 25 years (Silverman 1993).
In the clavicles, secondary ossification centers de- velop at both ends of the cartilaginous template (endo- chondral bone formation) around the 5th week of ges- tation, and ossification progresses toward the middle portion thereafter.A thin layer of cartilaginous tissue is left at the medial and at the lateral side to form what will become the articular cartilage of the intervening
joints, that is to say the sternoclavicular joint and the acromion-clavicular joint, respectively. The middle portion of the clavicle develops by virtue of intramem- branous (mesenchymal) bone formation, a process in which bone is formed without an intervening cartilagi- nous model, simply by deposition of calcium phos- phate into the osteoid matrix produced after transfor- mation of the original mesenchymal cells into active osteoblasts (Resnick et al. 1995). A secondary center appears at the medial end at approximately 20 years, and fuses with the body at about 25 years of age.
The scapula begins to differentiate from the 4th to 6th cervical vertebrae at about the 5th week of gesta- tion. Ossification begins at about the 8th week, while scapular descent is completed at about the 12th week (Rockwood and Matsen 1990). At birth, the scapular body is ossified, while the coracoid, acromion, and gle- noid are cartilaginous. The primary ossification center for the coracoid appears soon after birth or within a few months. During adolescence, a secondary center for the coracoid, two centers in the acromial process, and multiple centers along the vertebral border of the scapula and in the rim of the glenoid cavity appear. Fu- sion of these centers with the main body of the scapula is accomplished between the ages of 15 and 30 years.
The pattern of ossification as outlined above is not constant, and significant interindividual variability is common.
References
McCormick WF, Nichols MM. Formation and maturation of the human sternum. I. Fetal period. Am J Forensic Med Pathol 1981; 2: 323–8
Resnick D, Manolagas SC, Niwayama G, Fallon MD. Histogene- sis, anatomy, and physiology of bone. In: Resnick D. Diag- nosis of joint and bone disorders. W.B. Saunders Company, Philadelphia, 1995 (3rd ed.), pp. 609–14
Rockwood CA, Matsen FA. The shoulder. W.B. Saunders Com- pany, Philadelphia, 1990, pp. 11–2
Silverman FN. Chest wall, diaphragm, and pleura. In: Silver- man FN, Kuhn JP: Caffey’s pediatric X-rays diagnosis. An integrated imaging approach. C.V. Mosby Company, St. Louis, 1993 (9th ed.), p. 405
Thorax
Alessandro Castriota-Scanderbeg, M.D.
Chapter 2
Abnormal Shape or Size of the Chest
This section summarizes the disorders associated with a substantial change in the shape or size of the thoracic cage, with an emphasis on those that are ge- netically determined. Although pectus excavatum and carinatum are primary anomalies of the sternum and chondrocostal junctions, they modify the tho- racic shape to a significant extent.
In normal subjects, the thorax is bilaterally sym- metrical and vertically elongated, with a narrow upper portion and wider lower two-thirds. Minor anatomical variations of the anterior chest wall, in- cluding prominent convexity of anterior rib or costal cartilage and mild pectus excavatum or carinatum, are common findings, occurring in one-third of the normal pediatric population. Similarly, sternal asym- metry and lateral deviations of the sternal axis are frequent anatomical variations. More severe changes are definitely abnormal.
As with other anatomical regions, there is a close link between proper development of the bony tho- racic structures and the appropriateness of the bio- mechanical forces applied to them. Therefore, in- tegrity of the respiratory function and anatomical supports, including the spinal column and thoracic musculature, are essential for normal development of the chest. Conversely, paralysis or weakness of the respiratory muscles, as seen in neuromuscular disor- ders, is associated with severe changes in the thoracic shape, including vertical elongation, central constric- tion, and bulging of the lowest portion of the thorax.
Small Thorax
䉴
[Unusually (often disproportionately) small thoracic cage]
This designation covers a heterogeneous group of disorders characterized both radiographically and clinically by a small thoracic cage. There is significant overlap between this section and that dealing with short ribs. Depending on the degree of the lung vol- ume reduction, subtle abnormalities of the respirato- ry function or fatal respiratory distress may result.
The pathologic counterparts range from small com- pression atelectases in mild cases to lung hypoplasia in severe cases (Turkel et al. 1985).Altered cardiac he- modynamics is another potential complication of the restricted thorax. A small thoracic cage has been de- tected prenatally by ultrasound in fetuses with osteo- genesis imperfecta type II (Brown 1984), campomel-
ic dysplasia (Tongsong et al. 2000), thoracopelvic dys- plasia (Hsieh et al. 1999), asphyxiating thoracic dys- plasia (Chen et al. 1996), and chondroectodermal dysplasia (Sergi et al. 2001).
A long narrow thorax is typical of thanatophoric dysplasia (OMIM 187600). Both the anteroposterior and lateral diameters are strikingly short, owing to the presence of very short ribs. Cupped costochon- dral junctions and posterior rib scalloping are also present. Additional features include severe platy- spondyly with central end-plate indentations; a char- acteristic pelvic shape with short and horizontal ilia, small sciatic notch, and short broad ischia and pubic bones; and short, broad, and bowed long bones. The group of disorders referred to as lethal short-limbed platyspondylic dwarfism (OMIM 151210), or thanato- phoric dysplasia variants because of their clinical re- semblance to classic thanatophoric dysplasia, com- prises the Torrance, San Diego, and Luton types. All are perinatally lethal disorders and are characterized by very short extremities, small thorax, large head,
Fig. 2.1. Platyspondylic lethal skeletal dysplasia (PLSD) or thanatophoric variants, Torrance type. Note small thorax, with short and horizontal ribs; severe platyspondyly; hypoplastic il- ia, with trident acetabular appearance; and small, rounded scapulae. Absence of spikes at the inferior scapular border rules out the Luton type of PLSD. (From Mortier et al. 1997)
short neck, coarse facies, and protuberant abdomen.
Radiologic manifestations include decreased ossifi- cation of the skull base, small thorax with thin ribs, severe wafer-like platyspondyly, hypoplastic ilia with horizontal acetabula, and short, relatively straight long bones with widened metaphyses (Horton et al.
1979; Winter and Thompson 1982) (Fig. 2.1). Al- though as a group they can be differentiated from thanatophoric dysplasia, the distinction between types is based mainly on chondro-osseous morphol- ogy. However, the particular appearance of the scapula in the Luton type, with two spikes projecting from the inferior scapular border, may assist in the differential diagnosis (Mortier et al. 1997). Thoracic features similar to those of thanatophoric dysplasia, but less severe, occur in homozygous achondroplasia.
In achondrogenesis type IA and IB (OMIM 200600, 600972), the thorax is small and barrel-shaped, with short, thin, horizontally oriented ribs, splayed rib ends, and multiple rib fractures (not present in all cases). In achondrogenesis type II (OMIM 200610) the skeletal phenotype is similar, but somewhat milder:
the ribs are not as thin, and nor are the long bones so severely shortened and bowed as in type I. Lack of ossification of vertebrae, sacrum, and ischial and pubic bones clearly differentiates achondrogenesis (type I or II) from thanatophoric dwarfism and short rib-polydactyly syndromes. The ribs in hypophos- phatasia, congenital lethal form (OMIM 241500) are short and thin, with unossified ends. Absent ossifica- tion of the calvaria, with the exception of some parts
of the skull base and facial bones, and large areas of unossified tissue in most of the bones, including the scapulae and iliac bones and the metaphyses of the tubular bones, are distinguishing features. Individu- als affected by any of the above conditions are still- born or die shortly after birth from respiratory fail- ure or intracranial hemorrhage. Asphyxiating tho- racic dysplasia, or Jeune syndrome (OMIM 208500), is characterized by a long, narrow thorax in both diam- eters, with moderately short, horizontal ribs, and ir- regular, widened costochondral junctions (Fig. 2.2).
There are significant interindividual variations in the size of the thorax (Oberklaid et al. 1977). Many cases have a fatal outcome in the newborn period due to pulmonary hypoplasia (Turkel et al. 1985), but in- stances of mild disease are also known (Giorgi et al.
1990). Affected children surviving beyond the neona- tal period manifest a relatively larger thorax and may suffer from recurrent respiratory infections rather than ventilatory insufficiency. Renal and pancreatic symptoms usually become manifest in the longer term survivors. The multisystem nature of this disor- der is demonstrated by the presence of periportal fi- brosis, bile duct proliferation, and pancreatic fibrosis in pathological studies (Turkel et al. 1985). The asso- ciation of small thorax with short ribs, characteristic configuration of the pelvis (small sciatic notches re- sulting in a heart-shaped pelvic inlet), and a benign course of the respiratory distress in the newborn period occurs in thoracopelvic dysostosis (OMIM 187770). The hands, spine, and skull are normal in this disorder, which is differentiated from asphyxiat- ing thoracic dysplasia on the basis of the benign clinical course, the absence of renal problems, and its seemingly dominant inheritance (Bankier and Danks 1983). Rib shortening of varying degree (from moderate to severe), together with laryngeal stenosis and small pelvis, is a feature in thoraco-laryngo- pelvic dysplasia (Barnes syndrome, OMIM 187760).
In the presence of severe rib shortening, lung hypoplasia results in early death. Pathological exam- ination reveals that the laryngeal cartilages are ab- normal and the costochondral junctions widely ex- panded, with histological evidence of ‘dystrophic’
changes (Barnes et al. 1969). Thoracic dysostosis (OMIM 187750) is a condition with clinical and radi- ographic manifestations confined to the thorax (Rabushka et al. 1973). Autosomal dominant inheri- tance is likely. The cardinal features include reduced anterior and posterior diameters of the thoracic cage, with short, irregularly shaped ribs closely resembling those of Melnick-Needles syndrome, and pectus excavatum deformity (Fig. 2.3). The pul-
Abnormal Shape or Size of the Chest 113
Fig. 2.2. Asphyxiating thoracic dysplasia in a male newborn.
Note elongated, narrow thorax, with short ribs and wide ante- rior ends. Also note handlebar clavicular configuration
monary function may be adversely affected in this condition. In patients with chondroectodermal dys- plasia (Ellis-van Creveld syndrome, OMIM 225500) the thorax is narrow, with short, poorly developed ribs (Fig. 2.4). About one half of the patients die in early infancy of cardiac or respiratory dysfunction.
As discussed elsewhere in this book, the pelvic fea- tures overlap with those of asphyxiating thoracic dysplasia in early life (Kozlowski et al. 1972). Both thoracic and pelvic changes normalize during child- hood. Unlike asphyxiating thoracic dysplasia, hand polydactyly, either pre- or postaxial, is a constant fea- ture in Ellis-van Creveld syndrome. In the presence of polydactyly, differentiation between asphyxiating thoracic dysplasia and Ellis-van Creveld syndrome may be not possible from the radiologic features alone in infancy (Langer 1968). Later in life, hamate- capitate fusion and a characteristic deformity of the proximal tibia (external slanting of the proximal end, with the epiphysis located medially) develop in chon- droectodermal dysplasia. Furthermore, congenital heart defects affect about two-thirds of patients with Ellis-van Creveld syndrome, while renal disease oc- curs in a large proportion of patients with asphyxiat- ing thoracic dysplasia. Thoracic restriction and poly- dactyly are also prominent features in the short rib-polydactyly syndromes. In short rib-polydactyly syndrome, type I (Saldino-Noonan, OMIM 263530) the ribs are severely short and horizontal, resulting in a small thorax; the tubular bones are unusually short and incompletely ossified, with pointed or ragged ends; hexadactyly is postaxial; and the pelvis is ab- normally shaped (small ilia, flattened acetabula with lateral and medial spurs). The thorax is also narrow and constricted with extremely short and horizontal ribs in short rib-polydactyly syndrome, type II (Ma-
jewski, OMIM 263520). The tibia is disproportionate- ly short, hexadactyly can be either pre- or postaxial, and the pelvis is grossly normal, with premature os- sification of the proximal femoral epiphyses. In short, pointed metaphyses are the distinguishing features of short rib-polydactyly syndrome type I, while short tibias are characteristic of type II. Infants with either type of short rib-polydactyly syndrome are born dead or die from cardiorespiratory failure within hours or days of birth. Patients with short rib-poly- dactyly syndrome, type III (Verma-Naumoff, OMIM 263510) show changes in the thorax (short and hori- zontal ribs), skull (short cranial base, bulging fore- head, depressed nasal bridge, flat occiput), pelvis (tri- dent appearance), vertebrae (platyspondyly), hands (postaxial polydactyly), and long bones (shortening, widened metaphyses, metaphyseal spurs) (Naumoff et al. 1977; Verma et al. 1975). The assumption that types II and III are distinct disorders has been ques- tioned (Sillence 1980). Moreover, it has been postu- lated that the short rib-polydactyly syndromes repre- sent a continuous spectrum with variable expressivi- ty rather than separate disorders (Sarafoglou et al.
1999). The familial occurrence of two sibs with mild asphyxiating thoracic dysplasia and a stillborn with short rib-polydactyly syndrome type III has suggest- ed that these conditions could be different manifesta- tions of a single disorder (Ho et al. 2000). Short rib- polydactyly syndrome type III compounded by or overlapping with oro-facio-digital syndrome type II (Mohr syndrome) has also been described (Young et al. 2001) (Fig. 2.5). Cerebro-costo-mandibular syn- drome (OMIM 117650), also known as ‘rib gap de- fects with micrognathia’ (Miller et al. 1972), is a rare disorder with mental retardation, palatal defects, mi- crognathia, glossoptosis, and severe costovertebral
Fig. 2.3 a, b. Thoracic dysos- tosis. The anterior ends of the ribs are short, with poorly de- veloped, wavy posterior por- tions; the upper thorax is con- stricted, giving the chest cage a bell-shaped configuration.
(Reprinted, with permission, from Rabushka et al. 1973)
a b
abnormalities. Chest X-ray discloses a small and nar- row thorax, with marked hypoplasia of the ribs, and typical gap defects in the posterior arches of the ribs – a clue to the diagnosis. Respiratory distress, gaps of
posterior ribs, and micrognathia are virtually con- stant manifestations. This disorder is usually spo- radic, but a few cases of horizontal or vertical trans- mission are known, suggesting genetic heterogeneity
Abnormal Shape or Size of the Chest 115
Fig. 2.4 a, b. Chondroectoder- mal dysplasia in a 25-week male fetus. a Note narrow, cylindrical thorax with short ribs. b The vertebrae are not affected. (From Sergi et al.
2001)
Fig. 2.5. aFrontal and b later- al whole-body radiographic images of a stillborn male neonate with short rib-poly- dactyly syndrome type III.
Note marked shortening of the ribs, resulting in narrow, elongated thorax. There is also severe shortening of the long bones, with metaphyseal spurs, a trident-shaped pelvis, and platyspondyly. Because this child also had oro-facial and digital anomalies typical of the Mohr syndrome, a diag- nosis of compounded SRPS- III and oro-facio-digital syn- drome type II (Mohr syn- drome) was suggested. (From Young et al. 2001)
a b
a b
with autosomal recessive and autosomal dominant inheritance (Plotz et al. 1996). The thoracic cage is al- so small in campomelic dysplasia (OMIM 114290, 211900), a disorder of the newborn that is character- ized by congenital bowing and angulation of long bones (especially the tibias), small scapulae, hy- poplastic and poorly ossified cervical vertebrae, large head, small facies, small hands, and slender clavicles and ribs (Maroteaux et al. 1971). Dislocation of the hips, talipes equinovarus deformities, and 11 pairs of ribs are common features. Most patients die in the neonatal period of respiratory distress resulting ei- ther from the small thoracic cage or from narrowed airways secondary to defective tracheobronchial car- tilages. Micrognathia, cleft palate, retroglossia, and hypoplastic lungs may further compromise the respi- ratory function (Houston eta l. 1983). Kyphomelic dysplasia (OMIM 211350) is a short-limb dwarfism characterized by very short angulated femurs and variable bowing of other long bones, with improve- ment of the bowing during childhood; flared and ir- regular metaphyses; mild limitation of joint motion;
normal cranium and psychomotor development; and
moderately short, flared ribs, resulting in a narrow chest and pigeon breast (Fig. 2.6). Disproportionate short stature is a persistent feature. This bent-bone dysplasia is distinguished from campomelic dyspla- sia by the presence in the latter of tibial bowing, hy- poplastic scapulae, mental retardation, and sex rever- sal (Hall and Spranger 1979; Turnpenny et al. 1990).
Atelosteogenesis type II (de la Chapelle syndrome, OMIM 256050) is a lethal short-limb dysplasia con- sisting of small thorax with short ribs, micromelia predominantly affecting the ulnas and fibulas, bowed long bones, small hands, equinovarus deformity, and cleft palate. Neonatal death may be secondary to pul- monary hypoplasia, laryngeal stenosis, or tracheo- broncho-malacia (Whitley et al. 1986).
Radiographic Synopsis AP and LL projections
The size of the thoracic cage is usually judged subjec- tively. Reliable measurement of the thoracic diame- ters is precluded by the variable degree of inspiration during film exposure.
1. Short, horizontal ribs; narrow thorax with respect to the abdomen (thanatophoric dysplasia and variants, homozygous achondroplasia, short rib- polydactyly syndromes)
2. Small, barrel-shaped thorax; short, thin, horizon- tal ribs with splayed ends, and (often) multiple fractures (achondrogenesis, type I)
3. Small thorax; short, horizontal ribs (thicker than in type I), with no fractures (achondrogenesis, type II)
4. Short, thin ribs with unossified ends (hypophos- phatasia, lethal form)
5. Long, narrow thorax (variable degree); moderate- ly short and horizontal ribs, with irregular and widened costochondral junctions (asphyxiating thoracic dysplasia)
6. Small, narrow thorax; markedly hypoplastic ribs, with typical posterior rib-gap defects (cerebro- costo-mandibular syndrome)
7. Small thorax; small scapulae; hypoplasia of the pedicles of the thoracic vertebrae; eleven pairs of ribs (campomelic dysplasia)
8. Narrow chest and pigeon breast; moderately short ribs, with flared ends (kyphomelic dysplasia) Associations
• Achondrogenesis types I and II
• Achondroplasia, severe form
• Antley-Bixler syndrome
• Asphyxiating thoracic dysplasia
• Atelosteogenesis types I and II
Fig. 2.6. Kyphomelic dysplasia. Note relatively narrow thorax with short, flared ribs; normal scapulae; and short, bowed fe- murs. (From Mortier et al. 1997)
• Barnes syndrome
• Campomelic dysplasia
• Cerebro-costo-mandibular syndrome
• Chondrodysplasia punctata
• Chondroectodermal dysplasia
• Chromosome trisomy 8 syndrome
• Cleidocranial dysplasia
• Diastrophic dysplasia
• Dyssegmental dysplasia
• Fibrochondrogenesis
• Hypochondrogenesis
• Hypophosphatasia
• Jarcho-Levin syndrome
• Lethal short-limbed dysplasia with platyspondyly
• Melnick-Needles syndrome (osteodysplasty)
• Metaphyseal chondrodysplasia (Jansen type)
• Metatropic dysplasia
• Noonan syndrome
• Oligohydramnios
• Osteogenesis imperfecta, type II
• Progeria
• Pseudoachondroplasia
• Pterygium syndrome (lethal form)
• Short rib-polydactyly syndromes
• Shwachman syndrome
• Spondylo-epi-metaphyseal dysplasia with joint laxity
• Spondylo-epiphyseal dysplasia congenita
• Thanatophoric dysplasia
• Thoracic dysostosis
• Thoracopelvic dysostosis
References
Bankier A, Danks DM. Thoracic-pelvic dysostosis: a ‘new’
autosomal dominant form. J Med Genet 1983; 20: 276–9 Barnes ND, Hull D, Symons JS. Thoracic dystrophy. Arch Dis
Child 1969; 44: 11–7
Brown BS. The prenatal ultrasonographic diagnosis of osteo- genesis imperfecta lethalis. J Can Assoc Radiol 1984; 35:
63–6
Chen CP, Lin SP, Liu FF, Jan SW, Lin SY, Lan CC. Prenatal diag- nosis of asphyxiating thoracic dysplasia (Jeune syndrome).
Am J Perinatol 1996; 13: 495–8
Giorgi PL, Gabrielli O, Bonifazi V, Catassi C, Coppa GV. Mild form of Jeune syndrome in two sisters. Am J Hum Genet 1990; 35: 280–2
Hall BD, Spranger J. Familial congenital bowing with short bones. Radiology 1979; 132: 611–4
Ho NC, Francomano CA, van Allen M. Jeune asphyxiating tho- racic dystrophy and short-rib polydactyly type III (Verma- Naumoff) are variants of the same disorder. Am J Med Genet 2000: 90: 310–4
Horton WA, Rimoin DL, Hollister DW, Lachman RS. Further heterogeneity within lethal neonatal short-limbed dwarf- ism: the platyspondylic types. J Pediatr 1979; 94: 736–42
Houston CS, Opitz JM, Spranger JW, Macpherson RI, Reed MH, Gilbert EF, Herrmann J, Schinzel A. The campomelic syn- drome: review, report of 17 cases, and follow-up on the cur- rently 17-year-old boy first reported by Maroteaux et al. in 1971. Am J Med Genet 1983; 15: 3–28
Hsieh YY, Hsu TY, Lee CC, Chang CC, Tsai HD, Tsai CH. Pre- natal diagnosis of thoracopelvic dysplasia. A case report.
J Reprod Med 1999; 44: 737–40
Kozlowski K, Szmigiel C, Barylak A, Stopyrowa M. Difficulties in differentiation between chondroectodermal dysplasia (Ellis-van Creveld syndrome) and asphyxiating thoracic dystrophy. Australas Radiol 1972; 16: 401–10
Langer LO, Jr. Thoracic-pelvic-phalangeal dystrophy: asphyxi- ating thoracic dystrophy of the newborn, infantile thoracic dystrophy. Radiology 1968; 91: 447–56
Maroteaux P, Spranger JW, Opitz JM, Kucera J, Lowry RB, Schimke RN, Kagan SM. Le syndrome campomelique.
Presse Med 1971; 22: 1157–62
Miller KE, Allen RP, Davis W S. Rib gap defects with microg- nathia. AJR Am J Roentgenol 1972; 114: 253–6
Mortier GR, Rimoin DL, Lachman RS. The scapula as a win- dow to the diagnosis of skeletal dysplasias. Pediatr Radiol 1997; 27: 447–51
Naumoff P, Young LW, Mazer J, Amortegui AJ. Short-rib-poly- dactyly syndrome type 3. Radiology 1977; 122: 443–7 Oberklaid F, Danks DM, Mayne V, Campbell P. Asphyxiating
thoracic dysplasia. Clinical, radiological, and pathological information on 10 patients. Arch Dis Child 1977; 52: 758–65 Plotz FB, van Essen AJ, Bosschaart AN, Bos AP. Cerebro-costo- mandibular syndrome. Am J Med Genet 1996; 62: 286–92 Rabushka SE, Love L, Kadison HI. Isolated thoracic dysostosis.
Radiology 1973; 106: 161–5
Sarafoglou K, Funai EF, Fefferman N, Zajac L, Geneiser N, Paidas MJ, Greco A, Wallerstein R. Short rib-polydactyly syndrome: more evidence of a continuous spectrum. Clin Genet 1999; 56: 145–8
Sergi C, Voigtlander T, Zoubaa S, Hentze S, Meyberg-Solomey- er G, Troeger J, Tariverdian G, Otto HF, Schiesser M. Ellis- van Creveld syndrome: a generalized dysplasia of enchon- dral ossification. Pediatr Radiol 2001; 31: 289–93
Sillence DO. Non-Majewski short rib-polydactyly syndrome.
Am J Med Genet 1980; 7: 223–9.
Tongsong T, Wanapirak C, Pongsatha S. Prenatal diagnosis of campomelic dysplasia. Ultrasound Obstet Gynecol 2000;
15: 428–30
Turkel SB, Diehl EJ, Richmond JA. Necropsy findings in neona- tal asphyxiating thoracic dystrophy. J Med Genet 1985; 22:
112–8
Turnpenny PD, Dakwar RA, Boulos FN. Kyphomelic dysplasia:
the first 10 cases. J Med Genet 1990; 27: 269–72
Verma IC, Bhargava S, Agarwal S. An autosomal recessive form of lethal chondrodystrophy with severe thoracic nar- rowing, rhizoacromelic type of micromelia, polydactyly and genital anomalies. Birth Defects Orig Art Ser 1975; 11:
167–74
Whitley CB, Burke BA, Granroth G, Gorlin RJ. de la Chapelle dysplasia. Am J Med Genet 1986; 25: 29–39
Winter RM, Thompson EM. Lethal, neonatal, short-limbed platyspondylic dwarfism: a further variant? Hum Genet 1982; 61: 269–72
Young LW, Wilhelm LL, Zuppan CW, Clark R. Naumoff short- rib polydactyly syndrome compounded with Mohr oral- facial-digital syndrome. Pediatr Radiol 2001; 31: 31–5
Abnormal Shape or Size of the Chest 117
Pectus Excavatum
䉴
[Inward depression of the lower portion of the sternum]
Pectus excavatum, or funnel chest, is usually an iso- lated anomaly. However, it can also occur in associa- tion with other skeletal and nonskeletal defects or in the context of heritable disorders of the connective tissue, including Marfan syndrome and Ehlers-Dan- los syndrome. Moreover, the occurrence of idiopath- ic scoliosis in patients with anterior chest wall defor- mity is higher by a factor of 10 than in the general population (Waters et al. 1989). Pectus excavatum is usually present at birth and is progressive during growth. Its prevalence is 8 per 1000 births, with a male-to-female ratio of about 2:1. The degree of ster- nal depression varies from a shallow cup to a deep funnel (Fig. 2.7). Regardless of the degree of lower sternum depression, the manubrium remains at the normal level. Pectus excavatum has been classified into a broad and a localized type, according to the clinical extent of the sternal depression. In pectus ex- cavatum broad type (Fig. 2.8) the costal cartilages are involved to a greater extent, with inward bending be- ginning at the level of the costochondral junctions.
Impaired growth of the posterior portions of the cos- tochondral junctions coupled with relative over- growth of the anterior unaffected portions, is proba- bly responsible for the inward bending of the ster- num and thus for the development of the broad type
of pectus excavatum (Haje et al. 1999). In pectus exca- vatum, localized type (Fig. 2.9) impaired growth at the posterior costal growth plate and anterior por- tions of the sternum are likely to combine to deter- mine the sternal deformity (Haje et al. 1999). Anteri- or prominence of the lowest ribs can accompany both varieties of pectus excavatum.
Depending on the severity of the deformity and subsequent narrowing of the thoracic cavity, restric- tive pulmonary disease may result. A relationship be- tween pectus excavatum and exercise limitation has been reported in some patients. Right ventricular performance may also be adversely affected by this anomaly (Mocchegiani et al. 1995). Pectus excavatum may be associated with segmental bronchomalacia.
The psychological impact of this aesthetically unat-
Fig. 2.7. Isolated pectus excavatum in a 5-year-old girl. There is marked inward depression of the inferior portion of the sternum. Observe relative protrusion of the abdomen
Fig. 2.8. Pectus excavatum, broad type. Note the significant sternal depression beginning at the level of the costochondral junctions. (From Haje et al. 1999)
Fig. 2.9. Pectus excavatum, localized type. The sternal depres- sion is more focal than in the broad type. The costochondral junctions are minimally involved. The limits of the sternum and most inferior costal arches are marked with dashed lines.
(From Haje et al. 1999)
tractive deformity can be considerable (Ellis 1989) and is the single most common reason for requesting surgical repair (Myers 1991).
Congenital isolated pectus excavatum (OMIM 169300) has long been recognized as an anomaly oc- curring on a familial basis (Nowak 1936). Autosomal dominant inheritance with instances of male-to- male transmission has been reported (Leung and Hoo 1987). An autosomal dominant association of Pierre Robin sequence (micrognathia, glossoptosis, cleft palate) with pectus excavatum and rib/scapular
anomalies (OMIM 602196) has been reported in a family over five generations (Stalker and Zori 1997).
The severity of the pectus deformity varied from moderate to severe. The rib defects included single dysplastic rib and eleven pairs of ribs, while the scapular defect consisted of hypoplasia of the inferi- or subscapular area. Another association probably transmitted by an autosomal dominant inheritance comprises pectus excavatum, macrocephaly, short stature, and dysplastic nails (OMIM 600399) (Zori et al. 1992). Isolated malformation of the thoracic cage, known as thoracic dysostosis (OMIM 187750), in- volves short and deformed ribs similar to those of Melnick-Needles syndrome and pectus excava- tum, resulting in a constricted, bell-shaped thorax (Fig. 2.10 a, b). Pulmonary function can be adversely affected in this condition (Rabushka et al. 1973). An- terior chest deformity, including pectus excavatum and carinatum, is a cardinal feature of Marfan syn- drome (OMIM 154700), a disorder characterized by joint laxity, scoliosis, increased height, dispropor- tionately long limbs and digits, and arched palate.
Pectus excavatum occurs in about 70% of patients affected. Compared with isolated pectus excavatum, the deformity associated with Marfan syndrome manifests later in life, is progressive (Golladay et al.
1985), and tends to recur after surgical repair (Arn et al. 1989). Certain features of this disorder, including those with high diagnostic value, such as the doli- chostenomelia and arachnodactyly, as well as the an- terior chest wall deformities, can be explained as ex- cessive longitudinal growth of the parent bones. Ex- cessive longitudinal growth might in turn be related to a defect in the fibrous elements of the periosteum (McKusick 1956). The pulmonary function in these patients may be compromised by a restrictive venti- latory defect caused by pectus excavatum and scolio-
Abnormal Shape or Size of the Chest 119
Fig. 2.10 a, b. Isolated thoracic dysostosis in a 5-year-old boy.
aPosteroanterior and b lateral chest films show that the ribs are short anteriorly, and wavy and underdeveloped posteri- orly. The upper thorax is con- stricted, giving the chest cage a triangular (bell-shaped) con- figuration. A pectus excava- tum deformity is evident. Ob- serve the pulmonary infiltrate in the posterior basilar seg- ment of the left lower lobe.
(Reprinted, with permission,
from Rabushka et al. 1973) a b
Fig. 2.11. Schwartz-Jampel syndrome in a 7-year-old boy. Ob- serve mild depression of lower sternum
sis (Streeten et al. 1987). Obstructive respiratory dis- ease that is most prominent during sleep and caused by upper airway collapsibility and/or increased laxity of the pharyngeal wall may be a complication (Cistul- li and Sullivan 1995; Verbraecken et al. 1995). Pectus excavatum also sometimes accompanies those mal- formation spectra in which a marfanoid habitus is observed, including marfanoid mental retardation, X- linked type (OMIM 309520) (Lujan et al. 1984) and dominant type (OMIM 248770), microcephaly and glomerulonephritis (OMIM 248760), marfanoid hy- permobility syndrome (OMIM 154750), cutis laxa–
marfanoid syndrome (OMIM 150240), and homo- cystinuria (OMIM 2362000) (Visy et al. 1991).A shield chest with pectus carinatum superiorly and pectus excavatum inferiarly is characteristic of Noonan syn- drome (male Turner-like syndrome, OMIM 163950), an autosomal dominant disorder characterized by short stature, broad forehead, triangular face, ptosis, low-set ears, pterygium colli, low posterior hairline, and congenital heart defects. Kyphoscoliosis, verte- bral anomalies (Klippel-Feil, fusion), and limb defects (cubitus valgus, genu valgum, syndactyly, campto- dactyly) are frequent radiologic manifestations. Pec- tus excavatum also occurs in German syndrome (OMIM 231080), an association of ‘arthrogryposis,’
hypotonia-hypokinesia sequence, and lymphedema (German et al. 1975) and in the 3 M syndrome (OMIM 273750), a dwarfing condition with narrow facies, broad thorax with thin and horizontal ribs, clin- odactyly, and normal intelligence (Miller et al. 1975).
Although the most typical thoracic deformity in Schwartz-Jampel syndrome (OMIM 255800) is pectus carinatum, pectus excavatum can also be encountered (Fig. 2.11).
Radiographic Synopsis
Demonstration of pectus excavatum is best accom- plished by cross-sectional imaging (CT or MRI). The usefulness of plain radiography can be limited in children, because the bulk of the anterior chest wall is made of nonossified cartilage (Donnelly et al. 1999).
1. Lateral view
Body sternum depression, with inward bending of the costal cartilages at the same level. The manubrium is not affected, and the angle of Louis (manubriosternal junction) is increased. The body/manubrium index (i.e., the ratio obtained by dividing the length of the ossified body by the length of the ossified manubrium) is decreased in the localized type, but not in the wide type.
2. AP view
The posterior portions of the ribs are abnormally close to the horizontal, while the anterior portions
are steeply downward slanting; in severe cases, the heart tends to be displaced to the left and the pul- monary vascular markings in the right lower lobe are unusually conspicuous. Obliteration of the de- scending aortic interface, a radiographic finding caused by direct contact with, or proximity to, the aortic margin by pulmonary arteries, left inferior pulmonary vein, mediastinal fat, or left ventricle, correlates with the degree of cardiac displacement (Takahashi et al. 1992; Ward et al. 1989).
Associations
• Aarskog syndrome
• Coffin-Lowry syndrome
• Cowden syndrome
• Cutis laxa
• Ehlers-Danlos syndrome
• F syndrome (acro-pectoro-vertebral dysplasia)
• Fetal alcohol syndrome
• Freeman-Sheldon syndrome
• German syndrome
• Spondylometaphyseal dysplasia X-linked
• Homocystinuria
• LEOPARD syndrome
• Marfan syndrome
• Melnick-Needles syndrome (osteodysplasty)
• Myotonic dystrophy (Steinert syndrome)
• Mucopolysaccharidoses
• Noonan syndrome
• Schwartz-Jampel syndrome
• Simpson-Golabi-Behmel syndrome
• Shprintzen-Goldberg syndrome
• 3 M syndrome
References
Arn PH, Scherer LR, Haller JA, Pyeritz RE. Outcome of pectus excavatum in patients with Marfan syndrome and in the general population. J Pediatr 1989; 115: 954–8
Cistulli PA, Sullivan CE. Sleep apnea in Marfan’s syndrome: in- creased upper airway collapsibility during sleep. Chest 1995; 108: 631–5
Donnelly LF, Frush DP, Foss JN, O’Hara SM, Bisset GS. Anterior chest wall: frequency of anatomic variations in children.
Radiology 1999; 212: 837–40
Ellis DG. Chest wall deformities in children. Pediatr Ann 1989;
18: 161–5
German J, Morillo-Cucci A, Simpson JL, Chaganti RSK. Gener- alized dysmorphia of a similar type in 2 unrelated babies.
Birth Defects Orig Art Ser 1975; 11: 34–8
Golladay ES, Char F, Mollitt DL. Children with Marfan’s syndrome and pectus excavatum. South Med J 1985; 78:
1319–23
Haje SA, Harcke HT, Bowen JR. Growth disturbance of the ster- num and pectus deformities: imaging studies and clinical correlation. Pediatr Radiol 1999; 29: 334–41
Leung AKC, Hoo JJ. Familial congenital funnel chest. Am J Med Genet 1987; 26: 887–90
Lujan JE, Carlin ME, Lubs HA. A form of X-linked mental re- tardation with marfanoid habitus. Am J Med Genet 1984;
17: 311–22
McKusick VA. Heritable disorders of connective tissue. C. V.
Mosby Company, St. Louis, (1st ed.) 1956
Miller JD, McKusick VA, Malvaux P, Temtamy SA, Salinas CF.
The 3-M syndrome: a heritable low birthweight dwarfism.
Birth Defects Orig Art Ser 1975; 11: 39–47
Mocchegiani R, Badano L, Lestuzzi C, Nicolosi GL, Zanuttini D.
Relation of right ventricular morphology and function in pectus excavatum to the severity of the chest wall deformi- ty. Am J Cardiol 1995; 76: 941–6
Myers NA. An approach to the management of chest wall de- formities. Prog Pediatr Surg 1991; 27: 170–90
Nowak H. Die erbliche Trichterbrust. Dtsch Med Wochenschr 1936; 62: 2003–4
Rabushka SE, Love L, Kadison HI. Isolated thoracic dysostosis.
Radiology 1973; 106: 161–5
Stalker HJ, Zori RT. Variable expression of rib, pectus, and scapular anomalies with Robin-type cleft palate in a 5-gen- eration family: a new syndrome? Am J Med Genet 1997; 73:
247–50
Streeten EA, Murphy EA, Pyeritz RE. Pulmonary function in the Marfan syndrome. Chest 1987; 91: 408–12
Takahashi K, Sugimoto H, Ohsawa T. Obliteration of the de- scending aortic interface in pectus excavatum: correlation with clockwise rotation of the heart. Radiology 1992; 182:
825–8
Verbraecken JA,Willemen M, de Cock W, Coen E, van de Heyn- ing P, de Backer W. Obstructive sleep hypopnea syndrome in a patient with Marfan syndrome treated with oxygen therapy. Respiration 1995; 62: 355–8
Visy JM, Le Coz P, Chadefaux B, Fressinaud C, Woimant F, Mar- quet J, Zittoun J, Visy J, Vallat JM, Haguenau M. Homo- cystinuria due to 5,10-methylenetetrahydrofolate reduc- tase deficiency revealed by stroke in adult siblings. Neurol- ogy 1991; 41: 1313–5
Ward CS, Halpin SFS, Wilson AG. The posteroanterior chest radiograph in depressed sternum. Clin Radiol 1989; 40:
139–43
Waters P, Welch K, Micheli LJ, Shamberger R, Hall JE. Scoliosis in children with pectus excavatum and pectus carinatum.
J Pediatr Orthop 1989; 9: 551–6
Zori RT, Stalker HJ, Williams CA. A syndrome of familial short stature, developmental delay, pectus abnormalities, distinc- tive facies, and dysplastic nails. Dysmorph Clin Genet 1992;
6: 116–22
Pectus Carinatum
䉴
[Ventral protrusion of the sternum and its costal cartilages]
Pectus carinatum, or pigeon breast, is characterized by ventral protrusion of the sternum with bilateral flattening of the lateral walls of the chest. The inci- dence of this deformity is only 1/10th that of pectus excavatum, although in other series a pectus carina-
tum/excavatum distribution of 1.4:1 has been report- ed (Pena et al. 1981). Pectus carinatum is more com- mon in boys than in girls, is usually diagnosed in children aged 4–5 years, and becomes more promi- nent during adolescence.
Although bronchopulmonary changes have been observed in both pectus carinatum and pectus exca- vatum, possibly reflecting a primary pulmonary de- fect, they are clinically relevant only in the latter con- dition, perhaps because of the superimposition of mechanical compression (Pena et al. 1981). In the majority of patients with pectus carinatum deformi- ty the ventilatory function is preserved and the de- formity is mainly a cosmetic and psychological prob- lem (Ellis 1989). Furthermore, compared with pectus excavatum, treatment in pectus carinatum either is more often conservative or provides better results (Vidal et al. 1977; Ottolenghi and Vecchioni 1981).
Based on the location of the apex of the protru- sion, three types of pectus carinatum have been de- scribed: superior, inferior, and lateral (Haje et al.
1999). The endochondral growth of the sternum and costal cartilage is regarded as a key element in the development of anterior chest wall deformities. In pectus carinatum superior type early fusion of the growth plates in the sternum leads to a disproportion between the arrested growth in the sternum and the normal growth in the costal cartilages. The result is that the sternum is abnormally short, with forward protrusion of its upper portion and inward depres- sion of its inferior portion (Fig. 2.12 a, b). The costal cartilages are elongated and vertically oriented. A similar pattern of sternal deformity occurs in Cur- rarino-Silverman syndrome (premature closure of sternal sutures, OMIM 184800) (Currarino and Sil- verman 1958). Associated manifestations include mi- crognathia, cryptorchidism, and congenital heart de- fect. This sternal deformity is also characteristic of Noonan syndrome (OMIM 163950). The pathogene- sis of pectus carinatum inferior type is more contro- versial (Fig. 2.13). Hypoplasia of the inferior seg- ments of the sternum while the costal cartilages con- tinue to grow can lead to forward protrusion of the inferior sternum, with lateral depressions (Harrison grooves) representing inward bending of the costo- chondral junctions. Alternatively, overgrowth of the lowest costal arches may produce comparable effects.
In the lateral type of pectus carinatum, a develop- mental asymmetry of the sternum may result in rota- tion of the sternum along its longitudinal axis, thus producing the sternal protrusion and ultimately the contralateral parasternal depression at the level of the costal cartilages (Haje et al. 1999).
Abnormal Shape or Size of the Chest 121
Like pectus excavatum, pectus carinatum also oc- curs most commonly as an isolated anomaly, but it can also be seen in conjunction with other skeletal or visceral anomalies. In a series of 152 patients with pectus carinatum requiring surgical correction, asso- ciated musculoskeletal abnormalities were found in 34 (scoliosis in 23, Poland syndrome in 4, neurofibro- matosis type 1 in 2, Morquio disease in 2, vertebral anomalies, hyperlordosis, and kyphosis in 1 case
each). A family history of chest wall deformities was present in 26% of the patients, and familial scoliosis in 12% (Shamberger and Welch 1987). Congenital heart defects (Iakovlev et al. 1990) and diaphragmat- ic hernias (Soylu et al. 2000) are associated with a higher frequency than is found in the general popu- lation. Multiple skeletal abnormalities, including pectus carinatum or excavatum, acetabular dyspla- sia, and bowed long bones, together with short stature, myotonia, expressionless face, myopia, ble- pharophimosis, joint contractures, and spinal mal- alignment, are manifestations of Schwartz-Jampel syndrome (OMIM 255800), an autosomal recessive disorder (Aberfeld et al. 1965; Schwartz and Jampel 1962). Early diagnosis and treatment with carba- mazepine can resolve myotonia and prevent the de- velopment of classic skeletal anomalies (pectus cari- natum, stiff joints, bowed bones) (Squires and Pran- gley 1996). Prune-belly sequence (OMIM 100100) displays several musculoskeletal abnormalities, in- cluding clubfeet, limb deficiencies, hip dysplasia, vertebral malformations, scoliosis, and pectus exca- vatum and/or carinatum (Loder et al. 1992). In Cof- fin-Lowry syndrome (OMIM 303600) either pectus carinatum or pectus excavatum may be seen, togeth- er with a short sternum and thoracic kyphosis. These deformities can also occur in Marfan syndrome (OMIM 154700) (Magid et al. 1990) and homocyst- inuria. In mucopolysaccharidosis type VII (OMIM 253220), a disorder with beta glucuronidase deficien- cy, pectus carinatum, gross thoracic kyphoscoliosis, and hip dysplasia are features (de Kremer et al. 1992).
An association of pectus carinatum, joint laxity, and a characteristic facies (frontal bossing, low nasal bridge, malar hypoplasia, parrot-like nose, and arched upper lips) has been observed in a brother and sister (Guizar-Vazquez et al. 1980).Another asso-
Fig. 2.12 a, b. Pectus carina- tum, superior type in a boy aat 2 months and b at 8 years of age. At 2 months the inferi- or sternal growth plates are closed, whereas the superior sternal body growth plate and the manubrium-sternal growth plate are narrowed. By 8 years of age complete fusion of all the growth plates has occurred; the sternum is short and anteriorly bowed
a b
Fig. 2.13. Pectus carinatum, inferior type in a 5-year-old girl.
Note short inferior segments of the sternal body (arrows) and ossified xiphoid process. The most superior sternal body seg- ment was of normal height, while the inferior segments were found on MRI study (not shown) to be irregular and hypoplas- tic. (From Haje et al. 1999)
ciation, SCARF syndrome (OMIM 312830), includes skeletal abnormalities, cutis laxa, ambiguous geni- talia, retardation of mental development, and facial abnormalities. Distinguishing skeletal abnormalities are pectus carinatum, craniosynostosis, joint hyper- extensibility, and abnormally shaped vertebrae (Koppe et al. 1989). Sternum carinatum has been re- ported, together with scoliosis, long slender fingers, camptodactyly, cryptorchidism, hypertonia, myopia, and mildly dysmorphic facies, in children with the rare deletion of chromosome 2p11-p13 (Wenger and McPherson 1997). It can be also found in a number of chromosome imbalances and aneuploidies, includ- ing trisomy 14 mosaicism (Petersen et al. 1986). Pec- tus carinatum, together with brachycephaly, large and poorly structured ears, strabismus, mild scolio- sis, growth retardation, and severe hypoplasia of the right cerebellar hemisphere and vermis, has been de- scribed in a 4-year-old boy with congenital hypothy- roidism (Mauceri et al. 1997). Pectus carinatum can also occur as a manifestation of Setleis syndrome (OMIM 227260), a rare autosomal dominant or re- cessive disorder characterized by a characteristic
‘coarse’ face, bitemporal ‘forceps marks,’ skin aplasia and discoloration, sparse hair, short palpebral fis- sures, conical teeth, and aberrant distal palmar creas- es (Tsukahara et al. 1995). Acquired, progressive pec- tus carinatum deformity has been described after cardiac surgery in infancy (Haje 1995).
Radiographic Synopsis
The general considerations concerning the imaging modalities discussed for pectus excavatum also apply in the case of pectus carinatum.
1. Lateral view
Short sternum (decreased body/manubrium in- dex; see the section headed “Pectus Excavatum”);
marked posterior angulation at the site of the nor- mal Louis angle (chondromanubrial junction); in- ward bending of the lower part of the sternum;
elongation and vertical orientation of the costal cartilages (pectus carinatum superior type; Cur- rarino-Silverman syndrome; Noonan syndrome) 2. Lateral view
Shortening of the inferior segments of the sternal body; forward protrusion of the inferior sternum;
lateral depressions (Harrison grooves) (pectus carinatum inferior type; Marfan syndrome) 3. Lateral view
The sternum is tilted around its longitudinal axis) (pectus carinatum lateral type)
Associations
• Asphyxiating thoracic dysplasia
• CHARGE syndrome
• Chromosome imbalances and aneuploidies
• Coffin-Lowry syndrome
• Currarino-Silverman syndrome (premature closure of sternal sutures)
• Dyggve-Melchior-Clausen syndrome
• Ehlers-Danlos syndrome
• Fetal alcohol syndrome
• Homocystinuria
• Hyperphosphatasia
• Hypothyroidism, congenital
• LEOPARD syndrome
• Marfan syndrome
• Mucopolysaccharidosis VII
• Noonan syndrome
• Osteogenesis imperfecta
• Pectus carinatum-joint laxity-peculiar face
• Prune-belly syndrome
• SCARF syndrome
• Schwartz-Jampel syndrome
• Setleis syndrome
• Spondylo-epi-metaphyseal dysplasia (Strudwick type)
• Spondyloepiphyseal dysplasia congenita
• 3 M syndrome
References
Aberfeld DC, Hinterbuchner LP, Schneider M. Myotonia, dwarfism, diffuse bone disease and unusual ocular and facial abnormalities (a new syndrome). Brain 1965; 88:
313–22
Currarino G, Silverman FN. Premature obliteration of the ster- nal sutures and pigeon-breast deformity. Radiology 1958;
70: 532–40
De Kremer RD, Givogri I, Argarana CE, Hliba E, Conci R, Bol- dini CD, Capra AP. Mucopolysaccharidosis type VII (beta- glucuronidase deficiency): a chronic variant with an oligosymptomatic severe skeletal dysplasia. Am J Med Genet 1992; 44: 145–52
Ellis DG. Chest wall deformities. Pediatr Rev 1989; 11: 147–51 Guizar-Vazquez J, Sanchez G, Manzano C. Peculiar face, pectus
carinatum and joint laxity in brother and sister. Clin Genet 1980; 18: 280–3
Haje SA. Iatrogenic pectus carinatum. A case report. Int Orthop 1995; 19: 370–3
Haje SA, Harcke HT, Bowen JR. Growth disturbance of the ster- num and pectus deformities: imaging studies and clinical correlation. Pediatr Radiol 1999; 29: 334–41
Iakovlev VM, Nechaeva GI, Viktorova IA. Clinical function of the myocardium and cardio- and hemodynamics in pa- tients with pectus carinatum deformity. Ter Arkh 1990; 62:
69–72
Abnormal Shape or Size of the Chest 123
Koppe R, Kaplan P, Hunter A, MacMurray B. Ambiguous geni- talia associated with skeletal abnormalities, cutis laxa, craniostenosis, psychomotor retardation, and facial abnor- malities (SCARF syndrome). Am J Med Genet 1989; 34:
305–12
Loder RT, Guiboux JP, Bloom DA, Hensinger RN. Muscu- loskeletal aspects of prune-belly syndrome. Description and pathogenesis. Am J Dis Child 1992; 146: 1224–9 Magid D, Pyeritz RE, Fishman EK. Musculoskeletal manifesta-
tions of the Marfan syndrome: radiologic features. AJR Am J Roentgenol 1990; 155: 99–104
Mauceri L, Ruggieri M, Pavone V, Rizzo R, Sorge G. Cranio- facial anomalies, severe cerebellar hypoplasia, psychomo- tor and growth delay in a child with congenital hypothy- roidism. Clin Dysmorphol 1997; 6: 375–8
Ottolenghi A, Vecchioni R. Funnel chest and pigeon chest today. Chir Pediatr 1981; 22: 37–41
Pena A, Perez L, Nurko S, Dorenbaum D. Pectus carinatum and pectus excavatum: are they the same disease? Am Surg 1981; 47: 215–8
Petersen MB, Vejerslev LO, Beck B. Trisomy 14 mosaicism in a 2 year old girl. J Med Genet 1986; 23: 86–8
Schwartz O, Jampel RS. Congenital blepharophimosis associat- ed with a unique generalized myopathy. Arch Ophthalmol 1962; 68: 52–7
Shamberger RC, Welch KJ. Surgical correction of pectus cari- natum. J Pediatr Surg 1987; 22: 48–53
Soylu H, Koltuksuz U, Kutlu NO, Sarihan H, Sen Y, Ustun N, Ba- ki A, Sonmezgoz E, Doegmacrurul M, Akinci A. Morgagni hernia: An unexpected cause of respiratory complaints and a chest mass. Pediatr Pulmonol 2000; 30: 429–33
Squires LA, Prangley J. Neonatal diagnosis of Schwartz-Jampel syndrome with dramatic response to carbamazepine. Pedi- atr Neurol 1996; 15: 172–4
Tsukahara M, Okabe T, Ohtsuka M, Furukawa S. Follow-up study in a patient with Setleis syndrome. Am J Med Genet 1995; 57: 444–6
Vidal J, Perdriolle R, Brahin B, Connes H, Fischbach C. Conser- vative treatment of deformities of the anterior chest wall.
Rev Chir Orthop Reparatrice Appar Mot 1977; 63: 595–608 Wenger SL, McPherson EW. Interstitial deletion 2(p11.2p13): a
rare chromosomal abnormality. Clin Genet 1997; 52: 61–2
Rib Abnormalities
Congenital anomalies of the ribs are relatively com- mon, accounting for about 2% of all skeletal malfor- mations (Coury and Delaporte 1954). Most congeni- tal defects are minor, isolated anomalies devoid of clinical significance. Examples include minor seg- mentation defects (fused or bifid ribs), supernumer- ary ribs, and hypoplastic/absent ribs. Other rib de- fects may cause clinical symptoms, such as a super- numerary cervical rib causing thoracic outlet syndrome or rib fusion causing structural scoliosis concave on the fusion side. Still other anomalies can have key significance in the diagnosis of distinct dis- orders, such as the ‘rib gaps’ characteristically found in cerebro-costo-mandibular syndrome.
Some rib abnormalities are reviewed below, with the emphasis on those relevant in the diagnosis of skeletal dysplasias and other inherited disorders. A brief mention is also given, when appropriate, to ac- quired conditions that can affect the ribs, such as fractures, primary benign and malignant lesions, metastatic lesions, and infectious diseases.
Although conventional radiography is sufficient for the diagnosis of many such rib diseases, a detailed anatomical evaluation of the ribs and surrounding soft tissues is only achieved by using cross-sectional imaging modalities (Edelstein et al. 1985). Regardless of the imaging technique used, most rib abnormali- ties can be overlooked if not looked for specifically (Guttentag and Salwen 1999).
References
Coury CH, Delaporte J. Les anomalies des côtes. Formes anato- mo-radiologique et incidences pratiques (à propos de 288 cas). Sem Hop Paris 1954; 30: 2656–81
Edelstein G, Levitt RG, Slaker DP, Murphy WA. CT observation of rib abnormalities: spectrum of findings. J Comput Assist Tomogr 1985; 9: 65–72
Guttentag AR, Salwen JK. Keep your eyes on the ribs: the spec- trum of normal variants and diseases that involve the ribs.
Radiographics 1999; 19: 1125–42
Short Ribs
䉴
[Ribs of decreased length]
Generalized shortening of the ribs leads to a narrow thorax. Given the significant overlap between these two topics, the reader is referred to the section head- ed “Small Thorax” in this chapter for a more detailed discussion. A few additional comments are provided here. Shortening may be confined to a single rib or to a few ribs and thus manifest as a focal lesion with no effects on the overall size of the thoracic cage. Such a situation may be due to a developmental defect or to superimposed lesions, either inherited or acquired in origin. Rudimentary or hypoplastic ribs are relative- ly common developmental anomalies that can be unilateral or bilateral in distribution and usually in- volve the first ribs. A rudimentary first rib can be mistaken for a cervical rib on radiographic examina- tions. The 12th pair is also frequently involved.
A single short rib can be observed in the context
of such conditions as multiple hereditary exostoses
(OMIM 133700), Ollier disease (OMIM 166000), and
Maffucci syndrome (OMIM 166000) owing to the in-
hibitory effect exerted on bone growth by the osteo- chondromas or enchondromas, respectively. In addi- tion to being short, the rib is also variably deformed in these conditions (Azouz 1987; Crandall et al. 1984).
Chondroid lesions nearly always arise at or near the anterior end of the rib and manifest as a rib expan- sion irregularly calcified (Fig. 2.14).
Radiographic Synopsis AP and LL projections
1. Universal rib shortening, with smallness of the thoracic cage
2. Shortening of a single rib, or only a few ribs, owing to the presence of osteochondroma or enchondro- ma (multiple hereditary exostoses; Ollier disease;
Maffucci syndrome)
Associations
• Achondrogenesis types I and II
• Achondroplasia
• Asphyxiating thoracic dysplasia
• Atelosteogenesis
• Campomelic dysplasia
• Cerebrocostomandibular syndrome
• Chondroectodermal dysplasia
• Cleidocranial dysplasia
• Dyssegmental dysplasia
• Enchondromatosis (Ollier disease)
• Fibrochondrogenesis
• Hypochondrogenesis
• Hypophosphatasia
• Immune deficiency (severe combined) and adenosine deaminase deficiency
• Jarcho-Levin syndrome
• Maffucci syndrome
• Mandibuloacral dysplasia
• Melnick Needles syndrome (osteodysplasty)
• Metatropic dysplasia
• Mucopolysaccharidoses
• Multiple heritable exostoses
• Osteogenesis imperfecta type II
• Pseudoachondroplasia
• Rickets
• Short rib-polydactyly syndromes
• Spondylocostal dysostosis
• Spondyloepiphyseal dysplasia congenita
• Thanatophoric dysplasia
• Thoracic dysostosis
• Thoracopelvic dysostosis
• Thoracolaryngopelvic dysplasia (Barnes syndrome)
References
Azouz EM. Case report 418: Multiple enchondromatosis (Ol- lier disease) with severe vertebral changes. Skeletal Radiol 1987; 16: 236–9
Crandall BF, Field LL, Sparkes RS, Spence MA. Hereditary mul- tiple exostoses. Report of a family. Clin Orthop 1984; 190:
217–9
Hofman S, Heeg M, Klein JP, Krikke AP. Simultaneous occur- rence of a supra- and an infratentorial glioma in a patient with Ollier’s disease: more evidence for non-mesodermal tumor predisposition in multiple enchondromatosis. Skele- tal Radiol 1998; 27: 688–91
Eleven Pairs of Ribs
䉴
[Absence of a rib pair (most often the twelfth)]
Unilateral aplasia and uni- or bilateral hypoplasia of the 12th pair of ribs are common developmental er- rors that can occur in otherwise normal subjects. Be- cause these minor anomalies can also occur in ran- dom association with virtually every disease their di- agnostic value is limited. However, there is a small group of congenital disorders in which this defect consistently occurs.
Eleven pairs of ribs are typically encountered in the chromosome 18 trisomy syndrome (Edwards syn- drome) (Ho 1989; Poon et al. 1975), a disorder char- acterized by developmental and mental retardation, dolichocephaly, short palpebral fissures, overlapping
Rib Abnormalities 125
Fig. 2.14. Ollier disease in a 28-year-old man. The chondroid lesions with irregular calcifications are evident in both scapu- lae and the left 4th rib. (From Hofman et al. 1998)
fingers, and a variety of skeletal defects. These in- clude thin ribs, short sternum, reduced number of sternal ossification centers, and incomplete ossifica- tion of clavicles (Fig. 2.15). Eleven pairs of ribs are usually present in campomelic dysplasia (OMIM 114290, 211990). Together with congenital bowing
and angulation of the long bones – the radiographic and clinical stigmata of this disorder – slender ribs and clavicles, very small scapulae, and abnormalities of the skull, facial bones, pelvis and spine are fea- tures. In addition to some consistent structural rib anomalies, including hypoplasia and fusion, the au- tosomal dominant spondylocostal dysostosis (OMIM 122600) also manifests eleven pair of ribs (Fig. 2.16).
The vertebral anomalies include multiple level fu- sions, hemivertebrae, butterfly vertebrae, and sagittal clefts. The skull and limbs are not affected. Urinary system anomalies and congenital heart defects are usually present (Rimoin et al. 1968). Eleven pairs of mildly shortened ribs have been reported in the pres- ence of spinal changes associated with limb shorten- ing, severe acrodysplasia, multiple joint dislocations, and severe combined immune deficiency (SCID) (Castriota-Scanderbeg et al. 1997).
Radiographic Synopsis AP projection
1. Absence of a pair of ribs, most often the twelfth Associations
• Aase syndrome
• Asphyxiating thoracic dysplasia
• Atelosteogenesis
• Campomelic dysplasia
• Chromosome 1, partial deletion syndrome
• Chromosome 18 trisomy syndrome
• Cleidocranial dysplasia
• Developmental variant
• Down syndrome
• Femorofacial syndrome
• Short rib-polydactyly syndrome
• Spondylocostal dysostosis
References
Castriota-Scanderbeg A, Mingarelli R, Caramia G, Osimani P, Lachman RS, Rimoin DL, Wilcox WR, Dallapiccola B.
Spondylo-mesomelic-acrodysplasia with joint dislocations and severe combined immunodeficiency: a newly recog- nised immuno-osseous dysplasia. J Med Genet 1997; 34:
854–6
Ho NK. Eleven pairs of ribs of trisomy 18. J Pediatr 1989; 114:
902
Poon CC, Wong TT, Chan MC, Wong HB. Eleven pairs of ribs in E-trisomy. Arch Dis Child 1975; 50: 84
Rimoin DL, Fletcher BD, McKusick VA. Spondylocostal dyspla- sia: a dominantly inherited form of short-trunked dwarfism. Am J Med 1968; 45: 948–53
Fig. 2.15. Trisomy 18 syndrome (Edwards syndrome) in a male newborn. There are eleven pairs of thin, slender ribs. Ob- serve incomplete development of the clavicles, with medial de- ficiency
Fig. 2.16. Spondylocostal dysplasia, dominant type in a male newborn. Several anomalies of ribs (fusion, hypoplasia, eleven pairs) and vertebrae (hemivertebrae, butterfly vertebrae, sagit- tal clefts) can be seen. The scapulae and clavicles are unaffect- ed. (Courtesy of Dr. S. Fasanelli, Rome)
Supernumerary Ribs
䉴
[Increase in the number of ribs]
Accessory ribs can arise at the cervical, thoracic, or pelvic level. Cervical ribs can develop with a unilater- al or bilateral distribution, most commonly at the level of the seventh cervical vertebra. Rare instances of cervical ribs arising from the sixth cervical verte- bra are also well documented (Resnick 1995). Cervi- cal ribs appear as small ossicles or as fully developed bones that reach as far anteriorly as the first thoracic rib, with which they eventually articulate or fuse (Guttentag and Salwen 1999) (Fig. 2.17 a, b). An elon- gated transverse process of the seventh cervical ver- tebra can simulate a cervical rib. Isolated cervical ribs are often regarded as an anatomical variation rather than a true anomaly, with a reported preva- lence in the normal population ranging from 0.2%
(Etter 1944) to 8% (Schmidt and Freyschmidt 1993).
This anomaly has been related to the occurrence of brachial plexus neuropathies (thoracic outlet syn- drome) owing to encroachment of the cervical rib or a fibrous band connecting the accessory rib to the first rib on the neurovascular bundle as it exits from the thoracic outlet (Oates and Daley 1996; Crawford 1980). Selected patients may benefit from resection of the accessory rib. Cervical ribs are consistently associated with Simpson-Golabi-Behmel syndrome (OMIM 300209, 312870), an X-linked recessive disor- der characterized by gigantism, macrocephaly, mild mental retardation, coarse facies (down-slanting palpebral fissures, hypertelorism, broad flat nose), postaxial polydactyly of hands, syndactyly of feet, nail hypoplasia, broad thumbs and great toes, verte- bral segmentation defects (posterior fusion of C2/C3, six lumbar vertebrae, sacrococcygeal defects), and pectus excavatum (Gurrieri et al. 1992; Neri et al.
1988). A number of occasional abnormalities have been described, including cardiac defects, cleft lip/
palate, scoliosis, genitourinary anomalies, and cen- tral nervous system anomalies. Occasionally, cervical ribs are seen in cervico-oculo-acoustic syndrome (OMIM 314600), Turner syndrome, and trisomy 13 syndrome. Either supernumerary or absent ribs are frequently encountered in duplication 4p chromo- some syndrome, whereas supernumerary cervical ribs are found in deletion 4p syndrome (Wolf syn- drome) (Dunbar et al. 1975).
Intrathoracic ribs (Kamaruddin et al. 1995) are much less common than cervical ribs. They are uni- lateral, usually isolated, anomalies of the thorax (Fig. 2.18). The right side is more commonly in-
volved. Intrathoracic ribs can arise from the posteri- or margin of a normal rib or from the vertebral body itself. Often asymptomatic, on occasion they are re- sponsible for respiratory symptoms. Intrathoracic ribs that are not supernumerary have been reported
Rib Abnormalities 127
Fig. 2.17 a, b. Cervical supernumerary ribs in two adults. a Ob- serve the cervical rib at C-7 on the right side, articulating me- dially with an enlarged transverse process and laterally with an accessory bone seemingly fused with the first thoracic rib.
On the left side there is a transverse mega-apophysis extend- ing beyond the lateral margin of the transverse process at T-1.
Differentiation between cervical ribs and rudimentary first thoracic ribs is possible based on the orientation of the trans- verse processes: cervical processes are caudally oriented, while thoracic processes project cephalad. b Fully developed bilater- al cervical ribs with accessory articulation on the left side
a
b
(Kelleher et al. 1979). The midthoracic region is most commonly involved (Thery et al. 1976). The relation- ship of the accessory rib with the pleura, and the pos- sible presence of associated fatty tissue, can be best assessed by CT examination (Hawass et al. 1991).
Pelvic ribs are rare and are most commonly asymptomatic, being discovered as an incidental finding during radiographic examinations of the pelvis (Fig. 2.19). The site of attachment of the extra rib, which can be osseous, cartilaginous, or ligamen- tous, is a lumbar vertebra, or the sacrum, coccyx, ili- um, or acetabulum (Resnick 1995; Sullivan and Corn- well 1974; Dunaway et al. 1983). The size, shape, and spatial position of pelvic ribs are extremely variable.
Posttraumatic myositis ossificans, avulsion injuries of the pelvis (rectus femoris), and exostoses must be considered in the differential diagnosis (Greenspan and Norman 1982, 1984).
Incontinentia pigmenti (Bloch-Sulzberger syn- drome, OMIM 308300) is a disorder due to NEMO gene mutation at Xq28 and whose consistent features are irregular pigmented skin lesions, dental anom- alies (hypodontia, malformed teeth), and patchy alopecia. Skin lesions are characterized by inflamma- tory erythematous blisters, followed by verrucous, hyperkeratotic lesions developing on the distal limbs and scalp and hyperpigmentation of the trunk. Cen- tral nervous system (mental deficiency, spasticity or flaccidity, seizures, motor abnormalities, micro- cephaly), ocular (retinal ischemia, cataract, strabis- mus), and nail abnormalities occur in about one- third of affected patients. Skeletal abnormalities (about 20%) include hemivertebrae, kyphoscoliosis, supernumerary ribs, syndactyly, hemiatrophy, short- ening of legs and arms, skeletal maturation delay, and erosion of the terminal tufts of the phalanges (Spal- lone 1987; Landy and Donnai 1993). This X-linked dominant mutation is lethal in hemizygous males (The International Incontinentia Pigmenti Consor- tium 2000).
Rib anomalies, including supernumerary ribs (one or two supernumerary pairs), are an occasional feature of the VATER association.
Radiographic Synopsis 1. AP projection
Dense structure overlying the inner part of the lung field and generally running downward and backward within the thorax (intrathoracic ribs) 2. Lateral projection
Dense structure located posteriorly in the lung field (intrathoracic ribs)
Fig. 2.18. Thoracic supernumerary ribs in an 11-year-old girl.
There is a bone density shadow in the left-side of the thorax at the level of T-5, representing an intrathoracic rib. The rib was an incidental finding on a chest radiograph taken because of mild, right-sided pain, which was unrelated to the supernu- merary rib. (From Kamaruddin et al. 1995)
Fig. 2.19. Pelvic supernumerary ribs in a 15-year-old girl. Note pelvic rib curving anterolaterally and caudad for several cen- timeters from the right side of the sacral vertebra. The rib was discovered fortuitously on a radiograph obtained after a car accident. (Reprinted, with permission, from Sullivan and Cornwell 1974)
