title: A pedunculated follicular hamartoma: a case showing a central trichofolliculoma-like tumor with multiple trichogenic tumors.
abstract: We report a rare case with a pedunculated nodule on the nasal septum, which seems a kind of follicular hamartoma with a pedunculated appearance. Our case was a 77-year-old Japanese male with an 11 x 11 x 10 mm sized, skin-to-pink colored, pedunculated nodule on the center of his nasal septum. Histopathological study revealed the nodule to be a well-formed dilated hair follicle at the central pore of the tumor, where keratin debris and vellus hairs were present. In addition, epithelial cells forming long thin strands or immature follicle-like structures had proliferated multifocally from the epidermis of the wall of the central follicle to the peripheral epidermis. One distinctive feature was the formation of a primary germinal bud with thick concentric collagen fibers and sparse elastic fibers. Although a combined tumor of trichofolliculoma with highly-graded desmoplasia, multiple trichogenic trichoblastomas, and perifollicular fibromas was suggested, calling it a pedunculated follicular hamartoma seemed more useful because the pathological features were basically similar to reported follicular hamartomas and the clinical feature was so distinctive.
authors.affiliation: Department of Dermatology, Otaru City General Hospital, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kato
authors.forename: H
authors.initials: H
authors.lastname: Ueno
mesh_terms: D000368:Aged; D002455:Cell Division; D003094:Collagen; D006197:Hair / Q000473:pathology*; D006222:Hamartoma / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins; D008297:Male; D009300:Nasal Septum / Q000473:pathology; D009669:Nose Neoplasms / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology* / Q000601:surgery
chemical_list: D007633:Keratins; D003094:Collagen