Table 1 Differential diagnoses for primary spinal melanoma with differentiating features
Features | Primary spinal melanoma | Metastatic Melanoma | Melanocytoma | Melanotic Schwannoma | Clear cell Sarcoma |
|---|---|---|---|---|---|
Age/Sex | 50–70/males | Any age | 5th decade/males | 20–50/males | 30–70/males |
Site | Spine/extradural intramedullary | Any site | Cervical, thoracic spine, posterior fossa, Meckels cave | CNS: thoracic spine Perivertebral tissue | Â |
Imaging | Extradural lesion | Nothing specific | Â | Extradural | Â |
Gross | Soft | Pigmented | Â | Soft, pigmented | Firm, grey, gritty |
Microscopy • Cellular atypia • Tissue invasion • Necrosis • Mitoses • Pigment | Present Present Coagulative Numerous + | Present Present + Numerous +/- | Variable/- Rare Rare Rare + | Variable Rare + /- +/- + | Present Present Present Present + in 60% cases |
Immunohistochemistry • CK • TTF1 • EMA • HMB45 • S100P • Melan-A • Ki-67 • Others | - - - + + + 8–10% MITF, MART-1 | - - - + + + 8–10% ---- | - - - + + - 1–4% MITF, MART-1 NKIC3 | - - - + + + -- GFAP± | + - - + + + 3–4% MITF, MCAM |
Molecular Alterations | GNAQ (37% cases) | BRAF V600E/NRAS/HRAS | PRKAR1A | PRKAR1A | t(12;22) |
Treatment preferred | Surgical Excision | Excision + chemotherapy | Excision | Excision | Excision + radiation |
Prognosis | Benign to indolent, rarely aggressive | Depends on stage | Indolent | Indolent to aggressive | Indolent to Aggressive |