Multiple-Digit Pigmented Bowen's Disease Induced by Human Papillomavirus in an Immunocompetent Child

Bowen's disease is a squamous cell carcinoma in situ, the most common malignancy of the nail unit. Presenting more frequently in the fingernails, common risk factors include ionizing radiation, oral exposure to arsenic or pesticides, dyskeratosis congenita, and quite commonly diverse subtypes of HPV. We report the first case of multiple periungual pigmented Bowen's disease in a pediatric patient.

A healthy 13-year-old boy presented with a 9-month history of a pigmented erythematous patch on the proximal nail fold of his 3rd right finger without associated symptoms. A punch biopsy was taken, and the diagnosis of Bowen's disease was made. The patient received photodynamic therapy and three cycles of imiquimod without response, and two new lesions appeared on the first and second right fingers. Surgical removal was performed on all lesions. A polymerase chain reaction detected an HPV type 16.

Multiple periungual Bowen's disease is rare, with the most frequent risk factors being HPV infection and chronic immunosuppression. Less than 10% of the cases present as longitudinal melanonychia. To date, there are no previous reports of multiple pigmented periungual Bowen's disease. HPV-induced Bowen's disease is usually present in adults aged between 22 and 89 years as persistent verrucae. In this case, koilocytosis and the fact that all lesions appeared on the right hand are suggestive of HPV infection.