Rules for Classification

The classification applies to all primary malignant bone tumours except malignant lymphomas, multiple myeloma, surface/juxtacortical osteosarcoma and juxtacortical chondrosarcoma. There should be histological confirmation of the disease and division of cases by histological type and grade.

TNM Clinical Classification

T – Primary Tumour

TX	Primary tumour cannot be assessed
T0	No evidence of primary tumour

Appendicular Skeleton, Trunk, Skull and Facial Bones

T1	Tumour 8 cm or less in greatest dimension (Fig. 304, 305)
T2	Tumour more than 8 cm in greatest dimension (Fig. 306, 307)
T3	Discontinuous tumours in the primary bone site (Fig. 308)

Spine

T1	Tumour confined to a single vertebral segment or two adjacent vertebral segments
T2	Tumour confined to three adjacent vertebral segments
T3	Tumour confined to four adjacent vertebral segments
T4a	Tumour invades into the spinal canal
T4b	Tumour invades the adjacent vessels or tumour thrombosis within the adjacent vessels

Note
The five vertebral segments (Fig. 309) are:

• Right pedicle
  
• Right body
  
• Left body
  
• Left pedicle
  
• Posterior element

Pelvis

T1a	A tumour no more than 8 cm in size and confined to a single pelvic segment with no extraosseous extension
T1b	A tumour greater than 8 cm in size and confined to a single pelvic segment with no extraosseous extension
T2a	A tumour no more than 8 cm in size and confined to a single pelvic segment with extraosseous extension or confined to two adjacent pelvic segments without extraosseous extension
T2b	A tumour greater than 8 cm in size and confined to a single pelvic segment with extraosseous extension or confined to two adjacent pelvic segments without extraosseous extension
T3a	A tumour no more than 8 cm in size and confined to two pelvic segments with extraosseous extension
T3b	A tumour greater than 8 cm in size and confined to two pelvic segments with extraosseous extension
T4a	Tumour involving three adjacent pelvic segments or crossing the sacroiliac joint to the sacral neuroforamen
T4b	Tumour encasing the external iliac vessels or gross tumour thrombus in major pelvic vessels

Note
The four pelvic segments (Fig. 310) are:

• Sacrum lateral to sacral foramen
  
• Iliac wing
  
• Acetabulum/periacetabulum
  
• Pelvic rami, symphysis and ischium

N – Regional Lymph Nodes

M – Distant Metastasis

pTNM Pathological Classification

The pT and pN categories correspond to the T and N categories.

Note
pM0 and pMX are not valid categories.