Periungual Bowen's disease with a narrow longitudinal melanonychia mimicking periungual warts

Abstract

We report a case of 50-year-old man with a warty plaque along the lateral nail fold of his right fourth finger. A longitudinal pigmented streak of the nail plate was observed just beside the warty plaque. Following confirmation of a diagnosis of Bowen's disease according to nail fold biopsy, en bloc removal of the lateral nail unit was performed. Histopathological examinations of the resected specimen revealed atypical keratinocytes in the epidermis of the lateral nail fold and nail bed epithelium. Polymerase chain reaction (PCR) revealed human papillomavirus (HPV) DNA in the specimen. Analysis of the PCR product using direct DNA sequencing revealed that the sequence corresponded to the L1 gene of HPV type 34. Immunohistochemical staining for HPV showed positive results in the epithelium. Although periungual Bowen's disease is rare, the clinical distinction of this condition from periungual warts is very difficult. Longitudinal melanonychia adjacent to the warty lesion provides a clue to the diagnosis of Bowen's disease of the nail unit.[Skin Cancer (Japan) 2018 ; 33 : 211-214]