Description of clinical aspects and microscopy of the hair shaft of a carrier of familial monilethrix

ABSTRACT Monilethrix is a genetic condition that affects the hair shaft. We describe a family with this disease, focusing on its clinical aspects and microscopic hair characteristics. The patient was a 10-year-old female with history of hypotrichosis. In addition to diffuse alopecia, there was brittle hair, with ruptures in the hair shaft at different levels. The hair had a nodular appearance at naked eye. Other family members had the same symptoms, what indicates an autosomal dominant pattern of inheritance. Microscopic analysis revealed capillary fibers with areas of elliptical nodular appearance interspersed with regions of dystrophic constriction.