Penile Carcinoma Cuniculatum: A Case Report of an Extremely Rare Subtype of Squamous Cell Carcinoma.

Carcinoma cuniculatum is a very rare subtype of well-differentiated squamous cell carcinoma affecting several anatomical locations, including the penis. In this paper, we describe a case report of penile carcinoma cuniculatum highlighting some unusual clinical features. The patient was 61-year-old with a cauliflower-like tumor of the glans penis of less than 1-year duration. Microscopic examination revealed a p16-negative well-differentiated squamous proliferation characterized by narrow and cystic spaces extending through the lesion. Carcinoma cuniculatum is characterized by a strong tendency to deep penetration, typically presenting in patients in their seventh to eighth decades and with a long duration of the disease. In contrast, the tumor presented herein occurred in a younger patient with a shorter disease duration and showed only shallow growth into the underlying structures. Since penile carcinoma cuniculatum is a local disease without metastatic potential (regardless of tumor size and disease duration), awareness of this entity is important, especially for distinguishing it from other more aggressive subtypes of squamous cell carcinoma, which require different therapeutic approaches.