Abstract
BACKGROUND:
Androgenic alopecia (Androgenetic Alopecia) 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 (Telogen Effluvium) is readily reversible. The arrector pili muscle (APM) connects the follicle to the surrounding skin.
OBJECTIVES:
To compare histopathological features of the APM in Androgenetic Alopecia and Telogen Effluvium.
METHODS:
Archival blocks of 4 mm scalp punch biopsies from 8 patients with Androgenetic Alopecia and 5 with Telogen Effluvium 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 Androgenetic Alopecia 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 Telogen Effluvium specimens, but could be attributed to these patients also showing evidence of Androgenetic Alopecia. Quantitative analysis showed that muscle volume decreased and fat volume increased significantly (P<0.05) in Androgenetic Alopecia compared to controls.
CONCLUSIONS:
APM degeneration and replacement with fat in Androgenetic Alopecia 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 Androgenetic Alopecia is treatment resistant. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
