Bone
Miscellaneous
TNM staging of tumors of bone (appendicular skeleton, pelvis and spine)

Editor-in-Chief: Debra Zynger, M.D.
Raul S. Gonzalez, M.D.

Topic Completed: 8 January 2019

Revised: 8 January 2019

Copyright: (c) 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: (staging [title]) (bone [title]) NOT myeloma NOT lymphoma "loattrfree full text"[sb]


Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez R. TNM staging of tumors of bone. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonestaging.html. Accessed August 21st, 2019.

Pathologic TNM staging of tumors of bone, AJCC 8th edition
Definition / general
  • Tumors arising in bone (including osteosarcoma, chondrosarcoma, Ewing sarcoma, spindle cell sarcoma, hemangioendothelioma, angiosarcoma, fibrosarcoma / myofibroid sarcoma, chordoma and adamantinoma) are covered by this staging system
  • Hematolymphoid tumors (primary malignant lymphoma, multiple myeloma) are not covered by this staging system
Essential features
  • AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
ICD coding
  • ICD-10: C41.9 - malignant neoplasm of bone and articular cartilage, unspecified
Primary tumor (pT)
Categorization for appendicular skeleton, trunk, skull and facial bones:
  • pTX: primary tumor cannot be assessed
  • pT0: no evidence of primary tumor
  • pT1: tumor ≤ 8 cm in greatest dimension
  • pT2: tumor > 8 cm in greatest dimension
  • pT3: discontinuous tumors in the primary bone site

Categorization for spine:
  • pTX: primary tumor cannot be assessed
  • pT0: no evidence of primary tumor
  • pT1: tumor confined to one vertebral segment or two adjacent vertebral segments
  • pT2: tumor confined to three adjacent vertebral segments
  • pT3: tumor confined to four or more adjacent vertebral segments or any nonadjacent vertebral segments
  • pT4: extension into the spinal canal or great vessels
    • pT4a: extension into the spinal canal
    • pT4b: evidence of gross vascular invasion or tumor thrombus in the great vessels

Note:
  • Spine segments include right body, left body, right pedicle, left pedicle and posterior element

Categorization for pelvis:
  • pTX: primary tumor cannot be assessed
  • pT0: no evidence of primary tumor
  • pT1: tumor confined to one pelvic segment with no extraosseous extension
    • pT1a: tumor ≤ 8 cm in greatest dimension
    • pT1b: tumor > 8 cm in greatest dimension
  • pT2: tumor confined to one pelvic segment with extraosseous extension or two segments without extraosseous extension
    • pT2a: tumor ≤ 8 cm in greatest dimension
    • pT2b: tumor > 8 cm in greatest dimension
  • pT3: tumor spanning two pelvic segments with extraosseous extension
    • pT3a: tumor ≤ 8 cm in greatest dimension
    • pT3b: tumor > 8 cm in greatest dimension
  • pT4: tumor spanning three pelvic segments or crossing the sacroiliac joint
    • pT4a: tumor ≤ 8 cm in greatest dimension
    • pT4b: tumor > 8 cm in greatest dimension

Note:
  • Pelvic segments include sacrum, iliac wing, pubic rami / symphysis / ischium and acetabulum / periacetabulum
Regional lymph nodes (pN)
  • pNX: regional lymph nodes cannot be assessed
  • pN0: no regional lymph node metastases
  • pN1: regional lymph node metastases

Note:
  • Bone sarcomas very rarely involve lymph nodes and therefore NX can generally be assumed to represent N0 unless nodal involvement is evident clinically or pathologically
Distant metastasis (pM)
  • pM0: no distant metastasis
  • pM1: distant metastasis
    • pM1a: lung
    • pM1b: secondary bone or other distant sites (including distant lymph nodes)
Prefixes
  • y: preoperative radiotherapy or chemotherapy
  • r: recurrent tumor stage
Stage grouping for appendicular skeleton, trunk, skull and facial bones
  • Stage IA:T1 N0 M0 G1, GX
  • Stage IB:T2 - 3 N0 M0 G1, GX
  • Stage IIA:T1 N0 M0 G2, G3
  • Stage IIB:T2 N0 M0G2, G3
  • Stage III:T3 N0 M0G2, G3
  • Stage IVA:any T N0 M1a any G
  • Stage IVB:any T N1 any Many G
  • any T any NM1b any G


Note:
  • There is no stage grouping for bone tumors of the spine or pelvis
Registry data collection variables
  • Grade: G1, G2, G3
  • Three dimensions of tumor size
  • Percentage of necrosis after neoadjuvant systemic therapy, from pathology report
  • Number of resected pulmonary metastases, from pathology report
Histologic grade (generally tumor specific)
  • GX: grade cannot be assessed
  • G1: well differentiated, low grade
  • G2: moderately differentiated, high grade
  • G3: poorly differentiated, high grade
Histopathologic type
Board review question #1
The 8th edition AJCC staging criteria incorporate a certain size cutoff for tumors of bone, with tumors smaller than or equal to the cutoff having a better prognosis than tumors larger than the cutoff. What is this cutoff?

  1. 2 cm
  2. 5 cm
  3. 8 cm
  4. 10 cm
Board review answer #1
C. 8 cm

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Board review question #2
Combined TNM staging groups are used for primary bone tumors that arise in which of the following locations?

  1. Facial bones
  2. Pelvis
  3. Spine
Board review answer #2
A. Facial bones. While all primary bone tumors should undergo TNM staging, an overall combined stage (e.g. Stage IIB) is determined for tumors of the appendicular skeleton, trunk, skull, and facial bones. Tumors of the pelvis or spine do not have combined stage groupings.

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