Analysis of alterations adjacent to invasive squamous cell carcinoma of the penis and their relationship with associated carcinoma

Background In contrast to vulvar squamous cell carcinoma (SCC), the etiologic factors and precancerous lesions associated with penile carcinoma remain uncertain. Objectives To describe the morphologic features of lesions adjacent to invasive penile SCC and their relationship with the associated carcinoma and to compare these associations with vulvar carcinoma. Methods This was a retrospective histologic analysis of 68 cases of penile SCC. Adjacent lesions were considered to be premalignant lesions. They were classified as penile intraepithelial neoplasia (PIN), squamous hyperplasia (SH), and lichen sclerosus (LS). PIN cases were divided into two subtypes depending on the extension of atypia throughout the epithelium and, by analogy, with the classification of the vulvar intraepithelial neoplasia (VIN). Thus they were designated as undifferentiated (or bowenoid) PIN, defined by full-thickness atypia throughout the epithelium, and differentiated PIN, characterized by atypia confined to the lower third of the epithelium. SCC subtypes were classified as usual, verrucous, warty (condylomatous), basaloid, and mixed. Results Undifferentiated PIN was observed in 22 cases; LS was observed in 26 cases. Differentiated PIN and SH (except for two cases) were associated with underlying LS. Undifferentiated PIN was always associated with warty (condylomatous) (4 cases), basaloid (16 cases) or mixed SCC (2 cases), and LS with usual (19 cases) or verrucous SCC (7 cases). Limitations This was a retrospective analysis Conclusion This study suggests that, similarly to vulvar carcinoma, penile SCC occurs in association with two types of penile lesions: undifferentiated (or bowenoid) PIN and LS-linked differentiated PIN and/or SH. It appears that the subtype of these carcinomas is related to these adjacent lesions.