Staging and Grading of Bone Tumors (Neoplasm)

Enneking (MSTS) Staging for Malignant Bone Tumors

A compartment is defined as “an anatomic structure of space bounded by natural barriers of tumor extension.” Intra-compartmental lesions are easier to delineate clinically, surgically, and radiographically than Extra-compartmental lesions and have a correspondingly higher chance of adequate removal without amputative procedures.

For spinal column tumors, the Enneking classification does not take into account the presence of a continuous epidural compartment, the neurologic implications, and the need for restoring spinal stability.

Grading of Sarcomas

Grade I:

• Low grade intramedullary osteosarcoma
• Parosteal osteosarcoma
• Osteo-fibrous dysplasia-like adamantinoma
• Clear cell chondrosarcoma

Grade II:

• Periosteal osteosarcoma
• Classic adamantinoma
• Chordoma

Grade III:

• Osteosarcoma (conventional, telangiectatic, small cell, secondary, high-grade surface)
• Undifferentiated high-grade pleomorphic sarcoma
• Ewing sarcoma
• Dedifferentiated chondrosarcoma
• Mesenchymal chondrosarcoma
• Dedifferentiated chordoma
• Malignancy in giant cell tumor of bone
• Angiosarcoma

Variable:

• Conventional chondrosarcoma (grade 1-3 according to Evans)
• Leiomyosarcoma of bone (grade 1-3 according to FNCLCC)

Enneking (MSTS) Staging for Benign Bone Tumors

AJCC staging for Malignant Bone Tumors

AJCC staging for Soft tissue Sarcomas

Campanacci staging (Radiological) for Giant Cell Tumor

Grade 1 – Intramedullary lesion confined to bone

Grade 2 – Thinned, expanded cortex

Grade 3 – Cortical breakout

Evans Histological Grading for Chondrosarcoma

Grade I – low cellularity, limited cytonuclear atypia, few multinucleated cells, a mainly chondroid matrix and the absence of mitoses

• 90% 5 year survival

Grade II – increased cellularity, and increased muco-myxoid degeneration of the matrix; moderate cytonuclear atypia and occasional mitoses

• 80% 5 year survival

Grade III – chondrosarcomas are highly cellular, with nuclear polymorphism, mitoses and a mostly myxoid matrix

• 30% 5 year survival

Reference: Evans, H. L., Ayala, A. G., & Romsdahl, M. M. (1977). Prognostic factors in chondrosarcoma of bone.A clinicopathologic analysis with emphasis on histologic grading. Cancer, 40(2), 818–831. doi:10.1002/1097-0142(197708)40:2<818::aid-cncr2820400234>3.0.co;2-b

Weinstein-Boriani-Biagini (WBB) Classification for Primary Spinal Tumors

The WBB surgical staging system describes the involvement of a specific vertebra in terms of sectors involved, arranged clockwise in 12 sectors on an axial vertebral face from the left side of the spinous process (1) to the right side of the spinous process (12). The tumor is further divided into five concentric layers of tissue penetration centered about the dural sac:

• A— Extra-osseous soft tissue
• B — Intraosseous superficial
• C — Intraosseous deep
• D — Extraosseous (extradural)
• E — Extraosseous (intradural)

Procedure required according to zone:

1. 4-8 or 5-9: Vertebrectomy (double approach)
2. 2-5 or 7-11: Sagittal resection (double approach)
3. 10-3: Posterior arch resection (posterior approach)

Surgical Margins according to Enneking Staging

Surgical margins according to plane of surgical dissection:

1. Intralesional: Tumor
   • Debulking
   • Curettage:
     • Simple – creating a cortical window and ‘scooping out’ the underlying tumor
     • Extended – use of adjuvants such as liquid nitrogen, phenol, polymethylmethacrylate, or thermal cautery
2. Marginal: Reactive zone or Pseudo-capsule
3. Wide: Normal tissue
4. Radical: Entire involved compartment