Atrichia with papular lesions: a differential diagnosis of alopecia universalis not to be missed.

Abstract

Atrichia with papular lesions (APL, OMIM 209500) is a rare autosomal recessive disease that is characterized by irreversible hair loss usually taking place in the first months of life1 . Papular lesions are frequently observed in patients appearing at approximately 2 years of age and consisting of cysts filled with keratin. Pathogenic variants in the hairless gene (HR) have been reported in APL2-5 HR encodes a zinc-finger transcription factor that is highly expressed in brain and skin. Lack of expression of this factor causes disruption of the normal growth cycle of the mature hair follicle resulting in alopecia and development of dermal cysts. We observed an unsuspected case of APL in a patient misdiagnosed as alopecia universalis for several decades.