title: A hyperpigmented perianal nodule.
abstract: Basal cell carcinoma (BCC) is the most common cutaneous malignancy. Ultraviolet light is an important risk factor for the pathogenesis of BCCs; the vast majority are found in sun-exposed areas. BCCs occurring in the perianal or genital regions are seldom seen. Less than 1% of all BCCs occur at these sites. Etiologic factors other than solar exposure must be taken into account for such cases. We report a rare case of BCC that was initially detected during a routine colonoscopy.
authors.affiliation: Department of Dermatology, University of Illinois, Chicago, IL, United States.
authors.forename: Steven
authors.initials: S
authors.lastname: Kahn
authors.forename: Michael A
authors.initials: MA
authors.lastname: Warso
authors.forename: Iris K
authors.initials: IK
authors.lastname: Aronson
mesh_terms: D001005:Anus Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D002280:Basal Cell Carcinoma / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis; D003113:Colonoscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D033162:Incidental Findings; D008544:Melanocytes / Q000473:pathology; D008545:Melanoma / Q000175:diagnosis; D008548:Melanosis / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008875:Middle Aged; D012878:Skin Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012883:Skin Ulcer / Q000209:etiology