title: Melanonychia induced by topical treatment of periungual warts with 5-fluorouracil.
abstract: Periungal and subungual warts are benign epidermal neoplasms caused by human papillomaviruses. They represent a challenge for management because of resistance to treatment. 5-flourouracil is an antimetabolite that interferes with DNA synthesis and inhibits RNA formation. We present a 32-year-old female with subungual and periungual warts of the fingers of both hands and first right toe. She was treated with 5-fluorouracil twice daily under occlusion plus 20 percent urea. After a month she presented with grayish transverse melanonychia along and parallel to the lunula with some maceration of the periungal folds. Nail pigmentation may be a consequence of dermal deposition by systemic drugs and less frequently by topical drugs. In this case melanonychia was induced by the topical application of 5-fluorouracil. The brown-grayish pigmentation, with parallel involvement of the lunula of all the nails treated, presented like that induced by systemically administered cytotoxic drugs.
authors.affiliation: Department of Dermatology, Hospital Dr. Manuel Gea González, Mexico City, Mexico.
authors.forename: Mariana Catalina
authors.initials: MC
authors.lastname: De Anda
authors.forename: Judith Guadalupe
authors.initials: JG
authors.lastname: Domínguez
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000963:Antimetabolites / Q000009:adverse effects*; D005260:Female; D005472:Fluorouracil / Q000009:adverse effects*; D006801:Humans; D009260:Nail Diseases / Q000175:diagnosis / Q000188:drug therapy*; D010859:Pigmentation Disorders / Q000139:chemically induced*; D014860:Warts / Q000175:diagnosis*
chemical_list: D000963:Antimetabolites; D005472:Fluorouracil