Lesion | Clinical features | Histology | Immunohistochemistry |
DFSP | Young to middle-aged adults | Spindle-shaped cells in storiform pattern | (+) Vimentin (spindled) |
Trunk | Pigmented cells (Bednar tumour) | (+) CD34 (spindled) | |
Low mitotic rate | (+) CD 10 (focal) | ||
Minimal cytological atypia | (+) Focal S-100 (pigmented) | ||
(+) Apolipoprotein D | |||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
(−) MiTF | |||
Atypical fibroxanthoma (pleomorphic undifferentiated sarcoma of skin) | Male predominance | Well-circumscribed lesion | (+) Vimentin |
Head and neck | Haphazard arrangement | (+) CD68 | |
Pleomorphic, spindled and epithelioid cells | (+) Lysozyme | ||
Numerous mitoses including atypical | (+) α-1 Antichymotrypsin | ||
Multinucleated giant cells | (+) Focal factor XIIIa | ||
(+) MSA or SMA | |||
(+) CD10 (diffuse) | |||
(−) S-100 | |||
(−) Keratin | |||
(−) Desmin | |||
(−) Mart1/MelanA | |||
(−) MiTF | |||
Malignant PNST | Buttocks and thighs | Fasciculated pattern of hyperchromatic spindle cells | (+) Focal S100 (subset) |
Rare in other skin locations | (+) NSE | ||
(+) Leu 7 | |||
(+) Myelin | |||
(+) p53 | |||
(+) HMGA2 | |||
(−) Neurofilament | |||
(−) HMB-45 | |||
(−) Mart1/Melan A | |||
(−) MiTF | |||
Cutaneous leiomyosarcoma | Adults in their 60s | Fascicules of spindle-shaped cells with eccentric vacuole | (+) Desmin |
Male predominance | Pleomorphism | (+) Caldesmon | |
Hair-bearing skin of lower extremities | Nuclear atypia | (+) Vimentin | |
Mitoses | (+) SMA | ||
(+) MSA | |||
(+) S-100 (rare subset) | |||
(−) Mart1/Melan A | |||
(−) HMB-45 | |||
(−) MiTF | |||
Epithelioid angiosarcoma | Elderly | Large epithelioid tumour cells | (+) CD31 |
May bleed spontaneously | Hobnail pattern | (+) CD34 | |
Scalp and neck | Irregular nuclei | (+) Focal SMA | |
Mitoses, including atypical ones | (+) Factor VIII-RA | ||
Vascular channels | (+) S-100 (rare subset) | ||
Extravasated red blood cells | (+) LMWCK (Cam5.2) | ||
(+) Pankeratin (AE1/AE3) | |||
(+) Cytokeratin 7 | |||
(−) HMB-45 | |||
(−) Mart 1/Melan A | |||
(−) MiTF | |||
Epithelioid sarcoma | Young adult | Polygonal tumour cells in nodular aggregates with spindle cells in periphery | (+) Cytokeratin |
Male | Pleomorphism | (+) Vimentin | |
Distal extremities | Occasional mitoses | (+) EMA | |
Central necrosis | (+) CD34 (subset) | ||
(−) S-100 | |||
(−) HMB-45 | |||
(−) Mart1/Melan A | |||
(−) MiTF | |||
Spindle cell squamous cell carcinoma | Elderly men | Spindled pleomorphic tumour cells | (+) 34βE12 |
Sun-exposed skin | No keratinisation | (+) AE1/AE3 | |
Head and neck | May show desmosomal junctions | (+) Cytokeratin 5/6 | |
Upper extremities | (+) P63 (nuclear) | ||
Upper back and chest | (−) S-100 | ||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
(−) MiTF | |||
Cutaneous malignant granular cell tumour | Rarely seen in children | Necrosis | (+) S-100 |
Larger than their benign counterparts | Spindling | (+) Calretinin | |
Vesicular nuclei with large nucleoli | (+) Inhibin | ||
Increased mitotic activity >2/10 HPF | (−) HMB-45 | ||
High N/C ratio | (−) Mart1/MelanA | ||
Pleomorphism | (−) MiTF | ||
Cutaneous lymphoproliferative disorders and other haematological malignancies | Can affect any age | Large pleomorphic mononuclear cells | (+) LCA (CD45) |
Depending on type of lymphoma: | |||
B cell markers | |||
T cell markers | |||
Blast markers | |||
Myeloma markers (CD138) | |||
(−) S-100 | |||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
Merkel cell carcinoma | Head and neck and extremities of older adults | Small monomorphic basophilic cells with round to oval shaped nuclei and scanty cytoplasm | (+) CK20 and LMWCK typical dot-like paranuclear or cytoplasmic staining |
Solitary rapidly growing hard nodule | Nuclei have finely granular dispersed chromatin and small inconspicuous nucleoli | (+) Variably for CD56, CD57, EMA, chromogranin and synaptophysin | |
Tumour cells mainly occupy the dermis, but pagetoid spread of the tumour cells into the epidermis can be seen | (−) S-100 | ||
(−) HMB-45 | |||
(−) Vimentin | |||
(−) Mart 1/Melan A | |||
(−) MiTF | |||
Malignant PEComa | Depends on type and site of PEComa | Clear or eosinophilic spindle-epithelioid cells | (+) HMB-45 |
Fascicular, nested, sheet-like patterns | (+) Mart1/MelanA | ||
Perivascular accentuation | (+) MiTF | ||
Multinucleated giant cells | (+) S-100 in 18% | ||
>8 cm in size, >1 mitotic figure/50 HPFs, necrosis | (+) SMA, MSA | ||
(+) Desmin | |||
(+) Cyclin D1 | |||
(+) Vimentin | |||
(+) Pan-cytokeratin | |||
Follicular dendritic cell sarcoma | Mostly affect adults | Spindle to ovoid cells arranged in storiform or fascicular pattern | (+) CD21 |
Intranodal or extranodal painless mass | Oval nuclei, distinct nucleoli, delicate nuclear membrane | (+) CD35 | |
Indistinct cell border | (+) CD23 | ||
Fibrillary cytoplasm | (+) Desmoplakin | ||
(+) EMA | |||
(+) Vimentin | |||
(+) S-100 in 35% | |||
(+) CD68 in 11% | |||
(+) Clusterin | |||
(+) Fascin | |||
(+) Podoplanin | |||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
(−) MiTF | |||
(−) Cytokeratin | |||
(−) CD30 | |||
(−) CD3 | |||
(−) CD79a | |||
(−) CD34 | |||
(−) CD1a | |||
Anaplastic/pleomorphic Kaposi sarcoma | HIV setting | Spindle to epithelioid cells arranged in solid sheets and fascicles | (+) CD34 |
Pleomorphic nuclei with prominent nucleoli | (+) D2-40 | ||
Atypical mitoses | (+) CD31 (patchy) | ||
Extravasated red blood cells | (+) HHV-8 latency-associated nuclear antigen-1 | ||
(+) VEGFR-3 | |||
(+) Podoplanin | |||
(−) S-100 | |||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
(−) MiTF | |||
Plexiform fibrohistiocytic tumour of the skin | Young patients | Plexiform pattern | (+) CD68 |
Female predominance | Spindled and histiocytoid cells | (+) SMA | |
Trunk, extremity, face | Osteoclast-type giant cells | (+) PGP 9.5 | |
Cellular pleomorphism, mitotic activity, vascular invasion (may sometimes look like non-necrotising granulomas) | (+) S-100A6 | ||
(+) MiTF | |||
(+) CD57 | |||
(−) HMB-45 | |||
(−) Mart1/MelanA | |||
Monomorphic spindle synovial sarcoma | Adolescents, young adults | Spindle and epithelioid cells | (+) EMA, HMWCK, LMWCK |
Lower extremities | High nuclear/cytoplasmic ratio | (+) Type IV collagen, CD57, rarely S-100 | |
Variable mitotic rate | (+) CD99, CD56, neurofilaments | ||
(−) Chromogranin, synaptophysin | |||
(−) HMB-45, Mart1/MelanA, MiTF | |||
Post-radiation sarcomas including rhabdomyosarcomas | Post-radiotherapy | Spindle cells | (+) Vimentin, other mesenchymal markers S-100 could be positive |
Cellular atypia | (−) HMB-45, Mart1/MelanA | ||
High mitotic rate |
DFSP, dermatofibrosarcoma protuberans; EMA, epithelial membrane antigen; HMB, human melanoma black; HMWCK, high molecular weight cytokeratin; LMWCK, low molecular weight cytokeratin; MiTF, microphthalmia transcription factor; MSA, muscle specific actin; NSE, neuron-specific enolase; PEComa, perivesicular epithelioid cell tumour; PGP, P glycoprotein; PNST, peripheral nerve sheath tumour; SMA, smooth muscle actin; VEGFR, vascular endothelial growth factor receptor.