title: Chronological changes in trichofolliculoma: Folliculosebaceous cystic hamartoma is not a very-late-stage trichofolliculoma.
abstract: Some authors have reported that the secondary hair follicles in trichofolliculomas (TF) undergo regressive changes and are subsequently replaced by the developed sebaceous elements, and that folliculosebaceous cystic hamartoma (FSCH) is a TF at a very late stage. In the present study, we revaluated the histopathological features of 40 TF lesions, focusing on their chronological changes. The results of the present study indicate that while the secondary follicles in the TF exhibited the hair cycle, the normal hair cycle was out of control, and tertiary hair follicles randomly developed from the involuting secondary follicles. The repeated development of hair follicles in this disordered hair cycle caused the development of chains of several continuous hair follicles in late-stage TF. In the TF lesions, no features indicating the replacement of the regressing secondary hair follicles by any sebaceous elements were observed, thereby suggesting that FSCH is not a very-late-stage TF.
authors.affiliation: Division of Dermatology, Nakao Clinic, Saga, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Misago
authors.affiliation: Division of Dermatology and Dermatopathology, Nippon Medical School Musashi Kosugi Hospital, Kawasaki, Japan.
authors.forename: Shin-Ichi
authors.identifier: http://orcid.org/0000-0001-7036-7084
authors.initials: SI
authors.lastname: Ansai
authors.affiliation: Sapporo Dermatopathology Institute, Sapporo, Japan.
authors.forename: Takaya
authors.initials: T
authors.lastname: Fukumoto
authors.affiliation: Sapporo Dermatopathology Institute, Sapporo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Anan
authors.affiliation: Sapporo Dermatopathology Institute, Sapporo, Japan.
authors.forename: Tetsunori
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Division of Dermatology, Nakao Clinic, Saga, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Nakao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005497:Follicular Cyst / Q000473:pathology*; D018859:Hair Follicle / Q000473:pathology*; D006222:Hamartoma / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D018295:Neoplasms, Basal Cell / Q000473:pathology*; D012627:Sebaceous Glands / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*; D055815:Young Adult
keywords: chronological change; folliculosebaceous cystic hamartoma; hair cycle; tertiary hair follicles; trichofolliculoma