21 Bone
(Primary malignant lymphoma and multiple myeloma are not included.)
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SUMMARY OF CHANGES
• T1 has changed from “Tumor confined within the cortex” to “Tumor 8 cm or less in greatest dimension.”
• T2 has changed from “Tumor invades beyond the cortex” to “Tumor more than 8 cm in greatest dimension.”
• T3 designation of skip metastasis is defined as “Discontinuous tumors in the primary bone site.” This designation is a Stage III tumor that was not previously defined.
• M1 lesions have been divided into M1a and M1b.
• M1a is lung-only metastases.
• M1b is metastases to other distant sites, including lymph nodes.
• In the Stage Grouping, Stage IVA is M1a, and Stage IVB is M1b.
INTRODUCTION
This classification is used for all primary malignant tumors of bone except primary malignant lymphoma and multiple myeloma. Cases are categorized by histological type (e.g., osteosarcoma, chondrosacrcoma) and by histologic grade of differentiation.
ANATOMY
Primary Site. All bones of the skeleton.
Regional Lymph Nodes. Regional lymph node metastasis from bone tumors is extremely rare.
Metastatic Sites. A metastatic site includes any site beyond the regional lymph nodes of the primary site. Spread to the lungs is frequent.
C40.0 Long bones of upper limb, scapula, and associated joints C40.1 Short bones of upper
limb and associated joints
C40.2 Long bones of lower limb and associated joints
C40.3 Short bones of lower limb and associated joints
C40.8 Overlapping lesion of bones, joints, and articular cartilage of limbs
C40.9 Bone of limb, NOS C41.0 Bones of skull and
face and associated joints C41.1 Mandible C41.2 Vertebral column C41.3 Rib, sternum, clavicle,
and associated joints
C41.4 Pelvic bones, sacrum, coccyx, and associated joints
C41.8 Overlapping lesion of bones, joints, and articular cartilage C41.9 Bone, NOS
DEFINITIONS Primary Tumor (T)
TX Primary tumor cannot be assessed T0 No evidence of primary tumor
T1 Tumor 8 cm or less in greatest dimension (Figure 21.1) T2 Tumor more than 8 cm in greatest dimension (Figure 21.2A, B) T3 Discontinuous tumors in the primary bone site (Figure 21.3)
T1 T1
<8 cm Cortex
<8 cm
FIGURE 21.1. T1 is defined as tumor less than 8 cm in greatest dimension whether the tumor is confined within the cortex or invades beyond the cortex.
T2
>8 cm Cortex
A
Cortex T2
>8 cm
B
FIGURE 21.2. A. T2 is defined as tumor more than 8 cm in greatest dimension whether the tumor is confined within the cortex or invades beyond the cortex.
B. T2 is defined as tumor more than 8 cm in greatest dimension whether the tumor is confined within the cortex or invades beyond the cortex.
Regional Lymph Nodes (N)
NX Regional lymph nodes cannot be assessed(1) N0 No regional lymph node metastasis N1 Regional lymph node metastasis Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis
M1 Distant metastasis M1a Lung (Figure 21.4)
M1b Other distant sites (Figure 21.5) Histologic Grade (G)
GX Grade cannot be assessed G1 Well differentiated—Low grade G2 Moderately differentiated—Low grade G3 Poorly differentiated—High grade G4 Undifferentiated—High grade(2)
STAGE GROUPING
IA T1 N0 M0 G1,2 Low grade
IB T2 N0 M0 G1,2 Low grade
IIA T1 N0 M0 G3,4 High grade
IIB T2 N0 M0 G3,4 High grade
III T3 N0 M0 Any G
IVA Any T N0 M1a Any G
IVB Any T N1 Any M Any G
Any T Any N M1b Any G
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T3
Cortex
Discontinuous tumors
FIGURE 21.3. T3 is defined as discontinuous tumors in the primary bone site.
FIGURE 21.5. M1b is defined as metastases to other distant sites, including lymph nodes.
FIGURE 21.4. M1a is defined as lung- only metastases.
Primary tumor
Metastasis (node)
Metastasis (node)
Metastasis (node)
Metastasis (bone) Primary
tumor Metastasis
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NOTES
1. Because of the rarity of lymph node involvement in sarcomas, the designation NX may not be appropriate and could be considered N0 if no clinical involvement is evident.
2. Ewing’s sarcoma is classified as G4.
