title: Melanocytic Hyperplasia in the Epidermis Overlying Trichoblastomas in 100 Randomly Selected Cases.
abstract: One hundred cases of trichoblastomas (large nodular, small nodular, cribriform, lymphadenoma, and columnar) were randomly selected and studied for the presence of melanocytic hyperplasia in the epidermis overlying the tumors, which was defined as foci of increased melanocytes in the basal layer of the epidermis (more than 1 per 4 basal keratinocytes). Focal melanocytic hyperplasia was detected in a total of 22 cases of trichoblastoma (22%), and this phenomenon was most frequently seen in columnar trichoblastoma (7 cases), followed by large nodular trichoblastoma (5 cases). The mechanism of epidermal melanocytic hyperplasia overlying trichoblastoma is unclear. Ultraviolet may be a contributing factor, as focal melanocytic hyperplasia was also detected in one-third of cases in the epidermis overlying uninvolved skin, usually associated with solar elastosis. This is further corroborated by the occurrence of the lesions predominantly on the face. Melanocytic hyperplasia overlying trichoblastoma appears to have no impact on the clinical appearance of the lesion and is recognized only microscopically. In an adequate biopsy specimen containing at least part of trichoblastoma, it should not cause any diagnostic problems.
authors.affiliation: *Department of Pathology, University Hospital of Cattinara, Trieste, Italy; †Sikl's Department of Pathology, Charles University in Prague, Medical Faculty in Pilsen, Pilsen, Czech Republic; ‡Department of Pathology, Clinical Research and Practical Center for Specialized Oncological Care, Saint Petersburg, Russia; §Department of Pathology, Medical Faculty, Saint Petersburg State University, Saint Petersburg, Russia; and ¶Dermatopathologie Friedrichshafen, Friedrichshafen, Germany.
authors.forename: Tahseen M M
authors.initials: TM
authors.lastname: Al Omoush
authors.forename: Michael
authors.initials: M
authors.lastname: Michal
authors.forename: Anastasia M
authors.initials: AM
authors.lastname: Konstantinova
authors.forename: Michal
authors.initials: M
authors.lastname: Michal
authors.forename: Heinz
authors.initials: H
authors.lastname: Kutzner
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kazakov
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004817:Epidermis / Q000473:pathology*; D005260:Female; D006201:Hair Diseases / Q000473:pathology*; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D008297:Male; D008544:Melanocytes / Q000473:pathology*; D008875:Middle Aged; D018294:Neoplasms, Adnexal and Skin Appendage / Q000473:pathology*; D055815:Young Adult