Basal cell carcinomas with unusual histologic patterns.

Uncommon histologic variants of basal cell carcinoma (BCC) can present a diagnostic challenge. In this case series, we describe 3 patients with unusual BCCs encountered in a dermatologic surgical unit over a 1-year period from September 2003 to September 2004. The formalin-fixed, paraffin-embedded histologic specimens were initially examined microscopically after staining with hematoxylin and eosin. Additional stains, including diastase periodic acid-Schiff, colloidal iron, carcinoembryonic antigen, and cytokeratin-20, were subsequently performed as appropriate. Of the 3 lesions, one exhibited apocrine differentiation and two demonstrated a trabecular growth pattern. Although BCCs demonstrating apocrine differentiation have previously been described, a trabecular growth pattern, to our knowledge, has not been previously reported for BCC.