title: Malignant hidroacanthoma simplex: a case report.
abstract: Hidroacanthoma simplex is a benign tumor of the skin originating from or showing differentiation to the sweat glands. It grossly resembles seborrheic keratosis of Bowen's disease and histologically shows intraepidermal focal growth of epithelial cells. Malignant transformation of this tumor is rare. We report a case of pigmented hidroacanthoma with malignant transformation in a 67-year-old woman. There was a 20-year history of a skin lesion on the right thigh, which first appeared as a small verrucous papule, progressed to a dark-brown colored patch, and then to a pigmented plaque. Histologically, the primary tumor was composed of small squamoid cells with marked cellular atypia. Most of the tumor cells were located in the epidermis. Immunohistochemically, the cytoplasm of some tumor cells showed a positive reaction for epithelial membrane antigen, but not for either carcino-embryonic antigen or the S-100 protein.
authors.affiliation: Department of Dermatology, Chungnam National University School of Medicine, Taejon, Korea.
authors.forename: W J
authors.initials: WJ
authors.lastname: Lee
authors.forename: Y J
authors.initials: YJ
authors.lastname: Seo
authors.forename: J S
authors.initials: JS
authors.lastname: Yoon
authors.forename: K B
authors.initials: KB
authors.lastname: Suhr
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: J K
authors.initials: JK
authors.lastname: Park
authors.forename: K S
authors.initials: KS
authors.lastname: Suh
mesh_terms: D018250:Acrospiroma / Q000737:chemistry / Q000473:pathology*; D000368:Aged; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D018396:Mucin-1 / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D012867:Skin / Q000737:chemistry / Q000473:pathology; D013544:Sweat Gland Neoplasms / Q000737:chemistry / Q000473:pathology*
chemical_list: D018396:Mucin-1; D009418:S100 Proteins; D007633:Keratins