An Unexpected Transformation: Malignant Spindle Cell Carcinoma Developed From Primary Basal Cell Carcinoma.

Spindle cell carcinoma (SpCC)/sarcomatoid carcinoma is a biphasic tumor with molecular and histopathological properties of both epithelial and mesenchymal tumors. SpCC usually occurs either in sun-exposed areas like the head, neck, upper extremities, and chest or in the areas of skin with prior radiation exposure or in immuno-suppressed individuals. Cutaneous SpCC is a very rare disease, with only a handful of reported cases so far. SpCC differs from conventional squamous cell carcinoma (SCC) with dermal infiltration of atypical keratinocytes as single cells with hyperchromatic eosinophilic cytoplasm and elongated, pleomorphic nuclei with multiple nucleoli, in contrast to cohesive nests or islands in SCC. The objective of this study is to complete a review of the current literature and present a rare manifestation of malignant SpCC which developed from a localized basal cell carcinoma following excision and radiation therapy (RT) in a 79-year-old female. We plan to elucidate the importance of a timely and accurate diagnosis of this disease in order to maximize treatment options and improve survival outcomes.