Destruction of the arrector pili muscle and fat infiltration in androgenic alopecia.
AuthorsTorkamani N, et al. Show all Journal
Br J Dermatol. 2014 Mar 3. doi: 10.1111/bjd.12921. [Epub ahead of print]
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 8 patients with AGA and 5 with TE were obtained. New 4 mm biopsies from 5 normal cases were used as controls. Serial 7 μm sections were stained with a modified Mason’s trichrome. “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 2 of 5 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 to 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. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
PMID 24579818 [PubMed - as supplied by publisher]