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Staging Systems (Enneking, AJCC)

Staging plays a crucial role in treatment planning and prognosis estimation for primary bone and soft tissue tumours. The two main systems used in orthopaedic oncology are:

Enneking Staging System (commonly used in surgical planning)

AJCC TNM Staging System (widely used in oncology)



 1. Enneking Staging – Bone Sarcomas


This system includes:

  • Grade (G): Histological aggressiveness

  • T (Tumour extension): Local vs extracompartmental

  • M (Metastasis): Distant spread

 2. Grade Classification (Enneking) 


G1 (Low Grade):

  • Mild atypia, mitosis <1/10 HPF

  • Examples: ACT, parosteal osteosarcoma

G2 (High Grade):

  • Distinct atypia, mitosis 1–2/10 HPF

  • Examples: Classic osteosarcoma, Grade 2 chondrosarcoma

G3 (Anaplastic/Dedifferentiated):

  • Marked atypia, mitosis >2/10 HPF

  • Examples: Ewing sarcoma, undifferentiated chondrosarcoma


 3. T & M Definitions (Enneking)

  • T1: Tumour within compartment

  • T2: Extension to soft tissue, skip metastasis, or pelvic involvement

  • M1: Presence of distant metastasis

 4. Enneking Stage Summary Table

  • Stage IA
    Grade 1 (low grade)
    Tumour confined within the bone (T1)
    No metastasis (M0)

  • Stage IB
    Grade 1
    Tumour has extended beyond the compartment (T2)
    No metastasis (M0)

  • Stage IIA
    Grade 2 or 3 (high grade)
    Tumour confined (T1)
    No metastasis (M0)

  • Stage IIB
    Grade 2 or 3
    Tumour has spread beyond compartment (T2)
    No metastasis (M0)

  • Stage III
    Any grade
    Any tumour extent
    Distant metastasis present (M1)


 5. AJCC Staging – Bone Tumours (8th Edition)

More commonly used by oncologists. Uses:

  • T (Tumour size)

  • N (Lymph node involvement)

  • M (Metastasis site: M1a = lung, M1b = other)

  • Grade (G1–G4)

 6. T Category Definitions (AJCC)


T1: ≤5 cm
T2: >5–10 cm
T3: >10–15 cm
T4: >15 cm



 7. AJCC Bone Staging Table


StageTNMGradeIAT1N0M0G1–2IBT2–T3N0M0G1–2IIAT1N0M0G3–4IIBT2N0M0G3–4IIIT3N0M0G3–4IVAny TN1 or M1Any MAny G



 8. AJCC – Soft Tissue Sarcomas (Extremity & Trunk)


Uses TNM + Grade system. Version 8 no longer considers superficial vs deep location.

Grade Definitions:

  • G1: Well-differentiated (e.g., liposarcoma)

  • G2: Moderately differentiated (e.g., leiomyosarcoma)

  • G3: Poorly/undifferentiated (e.g., pleomorphic or synovial sarcoma)


References

  • Siegel, G. W., & Biermann, J. S. OKU: Musculoskeletal Tumours 5

  • Choi, J. H., & Ro, J. Y. 2020 WHO Classification of Bone Tumours

  • Tanaka, K., & Ozaki, T. AJCC 8th Edition – Bone & Soft Tissue Tumours

Conventional osteosarcoma of the left thigh encasing femoral vessels and invading muscle planes; managed with left hip disarticulation after multidisciplinary evaluation.
Enneking Staging – Bone Sarcomas
Enneking Staging – Bone Sarcomas
AJCC Staging in Primary Bone Malignancies
AJCC Staging in Primary Bone Malignancies
AJCC – Soft Tissue Sarcomas
AJCC – Soft Tissue Sarcomas
8th AJCC Staging of Soft Tissue Sarcomas of the Extremities and Trunk
8th AJCC Staging of Soft Tissue Sarcomas of the Extremities and Trunk

Pleomorphic sarcoma of the left arm diagnosed by imaging and biopsy; treated with limb-salvage surgery and wide resection.
Synovial sarcoma was confirmed through imaging and biopsy. The patient underwent limb-salvage surgery with wide excision and free flap reconstruction.
humerus im nailing
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