Korean J Dermatol.
2001 Dec;39(12):1370-1376.
A Clinico-Pathological Study of Pressure Alopecia
- Affiliations
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- 1Department of Dermatology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Korea. tyyoon@med.chungbuk.ac.kr
Abstract
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BACKGROUND: Pressure alopecia(PA), also referred to as postoperative pressure-induced alopecia, is seen most often after prolonged pressure on the scalp during general anesthesia, with the head fixed in one position. It may also occur in chronically ill persons after prolonged bed rest in one position, which causes persistent pressure on one part of the scalp. It probably arises due to pressure-induced ischemia. Although a few clinical studies of PA have been reported, extensive histopathological study of transverse section has not been performed.
OBJECTIVE
The purpose of this study was to investigate the clinical features and histopathological characteristics of transverse section in PA in order to find differential points from other alopecic diseases.
METHODS
Enrolled in this study was a total of 12 patients confirmed as PA at the Chungbuk National University Hospital from 1991 to 2001. The hospital charts and transverse sections of histopathological slides were reviewed.
RESULTS
1. The male and female ratio was 3:1. The mean age of the patients was 37.7 years. The mean ages of male and female patients were 34.7 and 46.7 years, respectively. 2. Most commonly involved sites were the parietooccipital area(8 cases). Temporoparietal area(4 cases) was followed. Signs and symptoms including pain, tenderness, erythema, swelling or numbness were present in seven cases. Five cases presented no signs or symptoms. The clinical appearance of alopecic patches varied mimicking alopecia areata or trichotillomania very closely. The mean operation time was 6.8 hours(from 2 to 11) and the mean postoperation onset time was 14.7 days(from 9 to 25). The hair regrowth was apparent 14.3 weeks in average(from 10 to 24) after operation. All cases were recovered within 6 months without any treatment. 3. Histopathological examination showed nearly all catagen stage of hair follicles, incontinent melanin pigment(12 cases), a perifollicular inflammatory infiltrate(3 cases including follicular infundibulum level in 2 cases and inferior segment level in 1 case), fat necrosis and a foamy macrophage infiltrate(5 cases), and vascular thrombosis(2 cases).
CONCLUSION
The clinical appearance of PA varied mimicking alopecia areata or trichotillomania very closely. Histopathological findings could be similar to those of alopecia areata, but PA could be differentiated from alopecia areata by nearly all hair follicles in catagen stages, fat necrosis and a foamy macrophage infiltrate, vascular thrombosis, and the absence of a peribulbar lymphocytic infiltrate. The dermatologist should be aware of these characteristic findings of PA to avoid misdiagnosis and unnecessary additional treatments.
