Trichoscopy of Pressure-Induced Alopecia and Alopecia Areata: A Comparative Study.

Background: Pressure-induced alopecia is an uncommon type of alopecia. It can occur in both scarring as well as non-scarring form and occurs due to ischemia resulting from prolonged head immobilisation during surgery or hospitalisation. The patchy hair loss generally involves convexities of scalp specially vertex and occiput. The hair loss is usually noticed 3 -28 days after the inciting event and regrowth of hair occurs between 1 - 4 months. Objective: To describe trichoscopic features of pressure alopecia and compare it with the closest differential, alopecia areata. Methodology: It is a retrospective observational study. Trichoscopic features of six cases of pressure alopecia seen during the study period were compared with alopecia areata and analyzed using appropriate statistical methods. Results: The study had 30 cases, six cases of pressure alopecia and 24 cases of alopecia areata. The mean age of patients with pressure alopecia and alopecia areata was 45.16 and 29.08 years respectively. Comedone- like black dots, black dots and area of scarring were statistically significant for pressure alopecia while exclamation mark hairs were significant for alopecia areata. Conclusion: Trichoscopy is a non-invasive test for diagnosis of alopecia and "Comedone-like black dots" are unique trichoscopic feature of pressure alopecia. [ABSTRACT FROM AUTHOR]