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Title: Destruction of the arrector pili muscle and fat infiltration in androgenic alopecia.
Epworth Authors: Sinclair, Rodney
Other Authors: Torkamani, Niloufar
Rufaut, Nicholas
Jones, Leslie
Keywords: Androgenic Alopecia
Hair Loss
Follicle Miniaturization
Telogen Effluvium
Arrector Pili Muscle
Masson's Trichrome Stain
Adipose Tissue
Muscle Volume
Fat Volume
Chair of Dermatology, Epworth HealthCare
Head & Neck Clinical Institute, Epworth HealthCare
Issue Date: Jun-2014
Publisher: Wiley
Citation: Br J Dermatol. 2014 Jun;170(6):1291-8.
Abstract: BACKGROUND: Androgenic alopecia (AGA) is the most common hair loss condition in men and women. Hair loss is caused by follicle miniaturization, which is largely irreversible beyond a certain degree of follicular regression. In contrast, hair loss in telogen effluvium (TE) is readily reversible. The arrector pili muscle (APM) connects the follicle to the surrounding skin. OBJECTIVES: To compare histopathological features of the APM in AGA and TE. METHODS: Archival blocks of 4-mm scalp punch biopsies from eight patients with AGA and five with TE were obtained. New 4-mm biopsies from five normal cases were used as controls. Serial 7-μm sections were stained with a modified Masson's trichrome stain. 'Reconstruct' software was used to construct and evaluate three-dimensional images of the follicle and APM. RESULTS: The APM degenerated and was replaced by adipose tissue in all AGA specimens. Remnants of the APM remained attached to the hair follicle. There was no fat in the normal skin specimens. Fat was seen in two of five TE specimens but could be attributed to these patients also showing evidence of AGA. Quantitative analysis showed that muscle volume decreased and fat volume increased significantly (P < 0·05) in AGA compared with controls. CONCLUSIONS: APM degeneration and replacement with fat in AGA has not previously been described. The underlying mechanism remains to be determined. However, we speculate that this phenomenon might be related to depletion of stem or progenitor cells from the follicle mesenchyme, explaining why AGA is treatment resistant.
DOI: 10.1111/bjd.12921
PubMed URL:
ISSN: 1365-2133
Journal Title: British Journal of Dermatology
Type: Journal Article
Affiliated Organisations: Department of Dermatology, School of Medicine and Dentistry, University of Melbourne, Carlton, Victoria, Australia.
Type of Clinical Study or Trial: Comparative Study
Appears in Collections:Head & Neck

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