III.7
III.7.1 Definition
There is much debate regarding the term com- mon or typical nevus. In our view of melano- cytic nevi, you can clinically and dermoscopi- cally differentiate between common/typical and uncommon/atypical or dysplastic nevi. The term common nevus encompasses the flat com- mon nevus, the dermal nevus of the face (Mie- scher nevus), and the papillomatous dermal ne- vus of Unna. These two types of nevi are described in Chaps. III.13 and III.19.
Common nevi are the most frequent melano- cytic neoplasms. The number of common mela- nocytic nevi varies in different studies and is age dependent. Common nevi usually develop most frequently at puberty. In Caucasians the mean number of common nevi varies between 30 and 70 in the age between 30 and 40 years, whereas in darker ethnic races common nevi are less frequent. Besides host factors, such as pigmentary traits and hereditary factors, expo- sure to UV radiation is the most important en-
Chapter III.7
Common Nevus
Rainer Hofmann-Wellenhof and H. Peter Soyer III.7
Contents
III.7.1 Definition . . . .102
III.7.2 Clinical Features . . . .102
III.7.3 Dermoscopic Criteria . . . .102
III.7.4 Relevant Clinical Differential Diagnoses . . . .103
III.7.5 Histopathology . . . .103
III.7.6 Management . . . .103
III.7.7 Case Study . . . .103
References . . . .104
vironmental factor for the development of com- mon nevi. According to the current model of the natural evolution of common melanocytic nevi, these nevi begin as simplex lentigo, and then develop into junctional and later com- pound and dermal nevi. Finally, they completely vanish or end as fibrotic papule (Unna’s concept of “Abtropfung”; see Chap. III.1).
Epidemiological studies have consistently shown that the total number of melanocytic nevi is one of the strongest risk factors for the development of melanoma. The relative risk cal- culated in a meta-analysis was 6.3 for persons with more than 100 common nevi compared with persons with less than 15 nevi. The exact role of common nevi as precursors of melanoma is still under debate.
III.7.2 Clinical Features
The common nevus is a round or oval macule or flat papule with regular border and homoge- neous color. The color can vary from all shades of brown to black (Fig. III.7.1). The diameter is smaller than 6 mm. Common nevi are found mostly in skin that has been exposed to sun- light, but they may be seen on the entire skin.
III.7.3 Dermoscopic Criteria
The common nevus displays a regular overall architecture. Most often the global pattern is re- ticular, but globular or homogenous patterns are also common (Fig. III.7.2). No combinations of these global patterns are observed. The color is equally distributed and uniform. The com- mon nevus lacks specific local criteria.
Common Nevus
Chapter III.7
Common Nevus
Rainer Hofmann-Wellenhof and H. Peter Soyer III.7
III.7.4 Relevant Clinical Differential Diagnoses
Since in our view lentigo simplex represents a precursor of the flat common nevus, both can be separated only histopathologically. Solar len- tigo or actinic lentigo tend to be lighter than common nevi and are more irregularly bor- dered.
III.7.5 Histopathology
Flat common nevi are small, symmetric, sharply demarcated melanocytic lesions which are con- fined to the epidermis and papillary dermis.
The melanocytes are arranged in a small nest of similar size and shape. The nests are situated predominantly on the tips of the rete ridges.
Some equally distributed single melanocytes may be present. Cytomorphologically, the cells are uniform round or ovoid with monomor- phous nuclei. A sparse lymphocytic infiltration may be found in the papillary dermis.
III.7.6 Management
Common nevi do not require special treatment or follow-up. Individuals should be advised to perform self-examination with special alertness to changes in shape or color. Individuals with more than 100 common nevi should visit a der- matologist once a year for total-body examina- tion.
III.7.7 Case Study
Patient comment
A 31-year-old woman visited the office of the dermatologist because she noticed two new nevi after the summer vacation.
Questions asked by the physician
Do you still mention a growth or another change of the new nevi?
Clinical image including detailed description
Clinical examination revealed some flat nevi, all with a diameter fewer than 4 mm on the trunk and extremities.
Chapter III.7 103
Fig. III.7.1. Two common nevi on the chest of a 37-year- old man. The nevi are smaller than 4 mm and are regu- larly shaped and pigmented
Fig. III.7.2. Dermoscopic image of two common flat nevi. The larger nevus has a diameter of 3 mm. Both nevi are symmetric, uniform pigmented, and regularly bor- dered. The smaller nevus displays a prominent regular pigment network, whereas in the larger nevus there is only a faint network
104 R. Hofmann-Wellenhof, H.P. Soyer
III.7
Dermoscopic image including detailed description
Dermoscopic features of one nevus on the back revealed a uniform pigmented homogeneous pattern. The small depigmented area on the top of the lesion corresponded to the typical hy- popigmentation around a hair follicle.
Clinical diagnosis including relevant differential diagnosis
The diagnosis of a common flat melanocytic ne- vus was made without any difficulty.
(A flat seborrheic keratosis may be also taken into differential diagnosis, but early seborrheic keratoses, as a rule, tend to have more dull col- ors and a finely stippled surface.)
Performed management
No further treatment was necessary.
Comments
The clinical diagnosis of common flat melano- cytic nevus is undemanding. Dermoscopy serves more to calm concerned patients than to confirm the diagnosis. Patients should be ad- vised to perform self-examination and apply sun protection.
C
Core Messages
■ Common flat melanocytic nevi are the most frequently melanocytic neo- plasms.
■ Common flat nevus requires no special treatment.
■ More than 100 common melanocytic nevi indicate a significantly higher risk of developing melanoma.
References
1. Zhu G, Montgomery GW, James MR, Trent JM, Hayward NK, Martin NG, Duffy DL. A genome- wide scan for naevus count: linkage to CDKN2A and to other chromosome regions. Eur J Hum Gen- et 2007;15:94–102
2. Zalaudek I, Grinschgl S, Argenziano G, Marghoob AA, Blum A, Richtig E, Wolf IH, Fink-Puches R, Kerl H, Soyer HP, Hofmann-Wellenhof R. Age-related prevalence of dermoscopy patterns in acquired me- lanocytic naevi. Br J Dermatol 2006;154:299–304
Common Nevus Chapter III.7 105 3. Zalaudek I, Hofmann-Wellenhof R, Soyer HP, Fer-
rara G, Argenziano G. Naevogenesis: new thoughts based on dermoscopy. Br J Dermatol 2006;154:793–
4. Elder DE. Precursors to melanoma and their mim-794 ics: nevi of special sites. Mod Pathol 2006;19 (Suppl 2):S4–S20
5. Hussein MR. Melanocytic dysplastic naevi occupy the middle ground between benign melanocytic naevi and cutaneous malignant melanomas: emerg- ing clues. J Clin Pathol 2005;58:453–456
6. Gandini S, Sera F, Cattaruzza MS, Pasquini P, Abeni D, Boyle P, Melchi CF. Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer 2005;41:28–44
7. Bauer J, Garbe C. Acquired melanocytic nevi as risk factor for melanoma development. A comprehen- sive review of epidemiological data. Pigment Cell Res 2003;16:297–306
8. Worret WI, Burgdorf WH. Which direction do ne- vus cells move? Abtropfung reexamined. Am J Der- matopathol 1998;20:135–139
9. Schmoeckel C. Classification of melanocytic nevi:
Do nodular and flat nevi develop differently? Am J Dermatopathol 1997;19:31–34
10. Ackerman AB, Milde P. Naming acquired mela- nocytic nevi. Common and dysplastic, normal and atypical, or Unna, Miescher, Spitz, and Clark? Am J Dermatopathol. 1992;14:447–453
