Cornu cutaneum-like HPV 45 positive subungual squamous cell carcinoma.

A cornu cutaneum (cutaneous horn) is a clinical descriptive term referring to a skin tumor having the appearance of an animal horn. Histopathologically, the lesion may be associated with several different tumors. Along with some benign entities such as warts or seborrheic keratoses, a cutaneous horn may be also associated with actinic keratoses, Bowen disease and squamous cell carcinoma. When an underlying malignancy is present, the entire tumor must be removed with careful control of margins. We report a case of a 68-year-old man with a cornu cutaneum-like HPV 45 positive sub-ungual squamous cell carcinoma on the left second toe.