Atrichia

Atrichia is a rare form of congenital or early-onset alopecia in which hair is absent or extremely reduced, typically resulting in permanent hair loss. The term encompasses related conditions, most notably atrichia congenita (congenital atrichia) and atrichia with papular lesions (APL). Both forms are inherited mainly in an autosomal recessive pattern and have been linked to mutations in the HR gene, which encodes a hairless transcription factor necessary for normal hair follicle cycling.

In atrichia congenita, scalp hair, and often eyebrows and eyelashes, are absent from birth. In APL, hair is also absent but papular, keratotic lesions tend to appear in infancy or early childhood, reflecting follicular pathology. In both conditions, hair follicles are typically non-functional or permanently arrested in a non-growing phase, so regrowth is uncommon.

Diagnosis is clinical, supported by family history and, when available, genetic testing for HR mutations. Histopathology, if performed, may show absent or severely diminished hair follicles with fibrous remnants. The differential includes other forms of congenital alopecia and hypotrichosis.

There is no proven cure. Management focuses on cosmetic and psychosocial aspects, with options such as wigs, hair prostheses, and counseling. Skin surveillance is advised if papular lesions are present. Prognosis generally involves lifelong hairlessness; extracutaneous features are usually absent, and most patients have normal development. See also related hair disorders for broader context.