Basal cell carcinoma or not? Histological variants and mimics of the most common cutaneous malignancy

Basal cell carcinomas are the most common cutaneous malignancy encountered by dermatologists. Although most basal cell carcinomas have typical features and are easily diagnosed histologically, some basal cell carcinomas are problematic. Because the best evidence suggests that basal cell carcinomas arise from primitive stem cells that differentiate along follicular lines, it is not uncommon that this tumor may resemble and be confused with a variety of benign and malignant follicular and sweat gland tumors. This article will focus on some common and rare histological variants that may produce confusion, as well as salient features that will allow the correct diagnosis to be made.