Mucocutaneous pseudoepitheliomatous hyperplasia: a review.

Pseudoepitheliomatous hyperplasia, also called pseudocarcinomatous hyperplasia because of its resemblance to well-differentiated squamous cell carcinoma, is a reactive epithelial proliferation that is characterized by prominent irregular hyperplasia of the epithelium with tongue-like epithelial projections into the dermis. This reactive pattern may involve cutaneous or mucosal surfaces and has been described in association with a wide variety of stimuli including infectious, neoplastic, inflammatory, and traumatic among others. In this review, we will discuss the pathophysiology of pseudoepitheliomatous hyperplasia, the histopathological findings that are helpful in its differentiation from squamous cell carcinoma, and the spectrum of conditions that may show this unique feature on microscopic examination.