Recurrent Cutaneous Angiosarcoma of the Scalp With Aberrant Expression of S100: A Case Report

Angiosarcoma (AS) is a malignant mesenchymal neoplasm of endothelial origin with a predominantly lymphatic immunophenotype, which accounts for less than 1% of all sarcomas. Cutaneous AS of the scalp is associated with high rates of local recurrence and a poor prognosis. Histologically, poorly differentiated AS often comprises solid epithelioid cells, although rare variants involving spindle cells have been reported; diagnosis requires immunohistochemical analysis using vascular cell markers. We report on a cutaneous spindle-cell AS of the scalp in a female patient; key features included spontaneous regression after biopsy, local recurrence 2 years later, and aberrant nuclear staining for S100 protein in an area of the tumor not expressing CD34 or D2-40. Tumor cells exhibited positivity for vascular markers CD31, CD34, D2-40, ERG and FLI-1 and were negative for myoid markers (αSMA and desmin), epithelial (EMA and cytokeratin AE1/AE3) and melanocyte markers (HMB45 and melan-A). Cutaneous spindle-cell AS of the scalp is a rare variant with a poor prognosis. Diagnosis of spindle-cell AS was confirmed by immunohistochemical analysis using CD31, CD34, ERG, FLI-1, podoplanin (D2-40), and claudin-5. Although a number of authors have noted aberrant expression of cytokeratins, CD30, CD117 and neuroendocrine markers (synaptophysin and chromogranin A) in AS, intense positive nuclear staining for S100 protein in neoplastic cells has not hitherto been observed. This article reports on a spindle-cell AS of the scalp notable for aberrant expression of S100, spontaneous regression and recurrence 2 years later at the same site and displaying identical histological and immunohistochemical features.