Abstract
Alopecia areata is a nonscarring hair loss that usually causes round patches of baldness, but alopecia areata incognita (AAI) and diffuse alopecia areata (DAA) can cause a diffuse and acute pattern of hair loss. To analyze the clinical, trichoscopic, histological, and therapeutic features of AAI and DAA. The study was designed to include data of patients with histological diagnosis of AAI and DAA enrolled in our Hair Disease Outpatient Consultations. DAA had a greater involvement of the parietal and anterior-temporal regions, while AAI manifested itself mainly in the occipital-parietal regions. The most frequent pattern was empty yellow dots, yellow dots with vellus hairs, and small hair in regrowth, but the presence of pigtail hair was found almost exclusively in those with AAI. In cases of DDA, the finding of dystrophic hair and black dots was more frequent. The most frequent trichoscopic sign in both diseases was the presence of empty yellow dots, which, however, were described in a higher percentage in cases of DAA. The diseases have a benign course and are responsive to topical steroid therapy. Trichoscopy is very important for the differential diagnosis between the 2 diseases and to select the best site for biopsy. In the presence of diffuse hair thinning, these entities must be considered.
Highlights
Alopecia areata (AA) is a common cause of nonscarring hair loss that generally causes round patches of baldness on the scalp, or the whole scalp, or the entire body.In some patients, AA is characterized by a diffuse hair loss, commonly misdiagnosed as telogen effluvium or androgenetic alopecia
Androgenetic alopecia was reported in 95.23% of cases of areata incognita (AAI) but in only 24% of cases of diffuse alopecia areata (DAA)
These data may be related to Rebora’s [1] hypothesis, which affirms AAI is more frequent in patients with androgenetic alopecia because they have a high percentage of hair follicles in telogen and a low number of hair follicles in anagen with high mitotic activity
Summary
Alopecia areata (AA) is a common cause of nonscarring hair loss that generally causes round patches of baldness on the scalp, or the whole scalp, or the entire body.In some patients, AA is characterized by a diffuse hair loss, commonly misdiagnosed as telogen effluvium or androgenetic alopecia. Alopecia areata (AA) is a common cause of nonscarring hair loss that generally causes round patches of baldness on the scalp, or the whole scalp, or the entire body. First described by Rebora in 1987 [1], AAI is more common (about 86%) among young women, especially between 20 and 40 years old [2]. It is characterized by widespread and severe hair loss, which develops rapidly in a few weeks in AAI, while DAA can appear over a prolonged period. The most frequent trichoscopic sign in both diseases was the presence of empty yellow dots, which, were described in a higher percentage in cases of DAA. In the presence of diffuse hair thinning, these entities must be considered
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