Spindle cell squamous cell carcinoma

Rare, aggressive and fast-growing squamous cell carcinoma of the skin, characterized by a high propensity to metastasize.

The tumor presents clinically as a fast-growing, usually ulcerated, red or skin-colored, firm lump.

Histologically, the tumour is characterized by spindle cell, dedifferentiated, cytokeratin-positive, eosinophilic, pleomorphic epithelial formations embedded in a connective tissue stroma. Evidence of numerous nuclear polymorphisms and mitoses. Occasionally also multinucleated epithelial giant cells. Differentiation with formation of horn beads is usually absent.

The tumor cells stain with cytokeratins, especially those with high molecular weight such as: MNF116, AE1/3, CK5/6 as well as for p63 and p40. The tumor parenchyma does not express CD10 and SMA, S100, SOX10, desmin and the endothelial markers CD34, CD31 and ERG.

The most important histological differential diagnosis is the atypical fibroxanthoma (AFX).

Excision with a sufficient safety distance to all sides.

1. Defty CL et al.(2011) Basaloid squamous cell carcinoma with 'monster' cells: a mimic of pleomorphic basal cell carcinoma. J Cutan Pathol 38:354-356.
2. Ellis R et al.(2015) Pleomorphic spindle cell dermal neoplasm with dot-like keratin reactivity: keratin-positive AFX or carcinoma? J Cutan Pathol 42:847-852.
3. Kanner WA et al.(2010) CD10, p63 and CD99 expression in the differential diagnosis of atypical fibroxanthoma, spindle cell squamous cell carcinoma and desmoplastic melanoma. J Cutan Pathol 37:744-750.
4. Lagana SM et al.(2011) Pleomorphic (spindle and squamous cell) carcinoma arising in a peripheral mixed squamous and glandular papilloma in a 70-year-old man. Arch Pathol Lab Med 135:1353-1356.
5. Mariotti EB et al. (2023) Bleeding and rapidly growing nodule on the forearm of an 86-year-old woman. J Dtsch Dermatol Ges 21:667-669.