Pigmented lesion in the inguinal region.

Pigmented Bowen disease (PBD) is a rare tumor characterized by increased melanin pigment in the epidermis or papillary dermis in addition to the typical findings of Bowen disease. We report the case of a 60-year-old woman who presented with a 6-month history of a gradually enlarging solitary dark brown plaque in her right inguinal region. Histopathology showed hyperkeratosis with parakeratosis, acanthosis, disorganization of epidermal architecture, atypical keratinocytes, and increased melanin pigment of the papillary dermis. Considering the clinical and the histological evidence, a diagnosis of PBD was established. Complete resection confirmed the diagnosis. Pigmented Bowen disease is an unusual form of squamous carcinoma in situ. Other tumors in the differential diagnosis include pigmented basal cell carcinoma and superficial spreading melanoma.