Pseudo hyperplastic squamous cell carcinoma of the penis associated with lichen sclerosus. An extremely well-differentiated, nonverruciform neoplasm that preferentially affects the foreskin and is frequently misdiagnosed - A report of 10 cases of a distinctive clinicopathologic entity

We present 10 cases of well-differentiated, squamous cell carcinoma of the penis with pseudohyperplastic features. At presentation, the median age was 69 years. Seven of the tumors were multicentric, and the majority preferentially involved the foreskin inner mucosal surface. Grossly the tumors were typically flat or slightly elevated, white and granular, and measured approximately 2 cm. Characteristic histologic features included keratinizing nests of squamous cells with minimal atypia surrounded by a reactive fibrous stroma. In biopsies or individual areas of resected specimens, the differential diagnosis with pseudoepitheliomatous hyperplasia was difficult but when samples of adequate size were available, obvious evidence of infiltration was present. The adjacent squamous epithelium typically showed changes that are known to be associated with squamous cell carcinoma ranging from squamous hyperplasia to low-grade, and in a few cases high-grade, squamous intraepithelial lesions. Well-developed lichen sclerosus was seen in all cases. Patients were treated by circumcision or partial penectomy. With the exception of 1 patient who developed a glans recurrence 2 years after initial circumcision, follow-up after the initial surgical procedure has been uneventful. The majority of penile carcinomas with the high degree of differentiation seen in these cases are in the category of the verruciform tumors, either the verrucous or papillary carcinoma, not otherwise-specified subtypes. Experience with the cases reported in this series indicates that a subset of nonverruciform, often multicentric, tumors with a high degree of differentiation and pseudohyperplastic features occur and preferentially involve the foreskin. Because it was present in all cases, lichen sclerosus may play a precancerous role.