Penile cutaneous horn ten years after treatment of verrucous squamous cell carcinoma on penile glans: case report.

Penile cutaneous horn is a clinical term that describes protruding hyperkeratosis, usually conical in shape, located on penile glans. Penile localization of this lesion, predominantly located on sun-exposed areas, is very rare. The association with malignancy on the penis makes proper identification of these lesions essential. We present a 45-year-old man with a cutaneous horn, 25 mm in size, located on the basis of penile glans. The patient had a history of phimosis, pseudoepitheliomatous balanoposthitis, surgical excision of penile verrucous squamous cell carcinoma (SCC) and postoperative radiotherapy of carcinoma in situ on the same localization, ten years before. Complete surgical removal of the horn with separate excision of the margins and base was done. Pathologic examination revealed squamous hyperplasia with suspicion of carcinoma in situ. Additional negative p16(INK4a) immunohistochemical analysis confirmed benign proliferative lesion. DNA polymerase chain reaction for human papilloma virus infection was negative. These findings suggested sparing surgical procedure in our patient, without indication for partial penile amputation, but with mandatory follow-up. Our case confirmed the association of pseudoepitheliomatous balanoposthitis with verrucous SCC, as well as the possible influence of radiotherapy on the development of penile cutaneous horn. Additionally, we showed the important role p16(INK4a) immunohistochemical analysis in the differential diagnosis of alterations adjacent to invasive SCC of the penis.