A diagnostic approach to basaloid neoplasms of the skin: squamous is red; basals are blue but alas! If only that were true

Abstract

Basaloid neoplasms of the skin are often challenging not only to general pathologists but also dermatopathologists especially in the setting of partial sampling. While basal cell carcinomas make up most cutaneous neoplasms, there is a wide variety of both benign and malignant entities that have a basaloid morphology, which are particularly important to distinguish when present on skin in sensitive areas. Distinguishing between the malignant from the benign requires an understanding of the clinical presentation, histological correlation, emergence of new subclassification, as well as molecular discoveries. This chapter will examine the common cutaneous basaloid neoplasms encountered in routine practice and will highlight pitfalls to avoid misdiagnosis of rare but aggressive mimics.