Staging and Grading of Bone Tumors (Neoplasm)

Enneking (MSTS) Staging for Malignant Bone Tumors

Stage	Grade	Site	Metastasis
IA	Low	Intra-compartmental	None
IB	Low	Extra-compartmental	None
IIA	High	Intra-compartmental	None
IIB	High	Extra-compartmental	None
III	Any	Any	Regional or Distant

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

Stage	Definition	Biological behavior	Soft tissue tumor example	Bone tumor example
1	Latent	Remains static or heals spontaneously	Lipoma	Nonossifying fibroma
2	Active	Progressive growth, limited by natural barriers	Angiolipoma	Aneurysmal bone cyst
3	Aggressive	Progressive growth, invasive, not limited by natural barriers	Aggressive fibromatosis	Giant cell tumor

AJCC staging for Malignant Bone Tumors

Stage	Grade	Size	Metastasis
IA	Low	<8 cm	None
IB	Low	>8 cm	None
IIA	High	<8 cm	None
IIB	High	>8 cm	None
III	Any	Any	Skip metastases
IVA	Any	Any	Lungs
IVB	Any	Any	Regional lymph nodes or another distant site (non-pulmonary)

AJCC staging for Soft tissue Sarcomas

Stage	Grade	Size	Metastasis
IA	Low	<5 cm	None
IB	Low	>5 cm	None
II	High	<5 cm	None
IIIA	High	5-10 cm	None
IIIB	High	>10 cm	None
IV	Any	Any	Regional lymph node or distant metastases

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

Enneking Stages	Margin for Control
Benign
1	No management unless for decompression or stabilization
2	Intralesional excision ± local adjuvants
3	Marginal en-bloc excision
Malignant
Ia	Wide en-bloc excision
Ib	Wide en-bloc excision
IIa	Wide en-bloc excision + effective adjuvants
IIb	Wide en-bloc excision + effective adjuvants
III	Palliative

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