Trichoscopy - a useful tool in the preliminary differential diagnosis of autoimmune bullous diseases

Scalp is a common location of autoimmune bullous diseases. Trichoscopy is a noninvasive method for diagnosing hair and scalp diseases. Data on trichoscopy in autoimmune bullous diseases are limited to the studies on pemphigus including a small number of patients. Trichoscopic characteristics of bullous pemphigoid and dermatitis herpetiformis were not reported to date. The aim of the study was to determine the value of trichoscopy in the differential diagnosis of pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, and dermatitis herpetiformis.

Trichoscopy was used to evaluate scalp lesions in 68 patients (26 with pemphigus vulgaris, 17 with pemphigus foliaceus, 17 with bullous pemphigoid, and 8 with dermatitis herpetiformis). The working magnification was 20-fold and 70-fold.

The most frequent trichoscopic feature of autoimmune bullous diseases was extravasations. They occurred in 76.9% of patients with pemphigus vulgaris, 70.6% of patients with pemphigus foliaceus, 76.5% of patients with bullous pemphigoid, and 100% of patients with dermatitis herpetiformis. Yellow hemorrhagic crusts occurred in, respectively, 73.1%, 70.6%, 64.7%, and 35.5% of the cases. Yellow diffuse scaling and tubular scaling occurred more frequently in pemphigus foliaceus (52.9% and 41.2%, respectively). Clustered dotted vessels were characteristic for dermatitis herpetiformis (5/8, 62.5%). Dotted vessels with whitish halo were a hallmark of pemphigus vulgaris. A trichoscopic algorithm for the differential diagnosis of autoimmune bullous diseases was developed.

Autoimmune bullous diseases present characteristic trichoscopic patterns. Trichoscopy can be regarded as a rapid in-office preliminary diagnostic method in the differential diagnosis of these diseases.