Pili torti (PT) refers to a hair shaft that is flattened and twisted on its own axis with a range of 90 to 360 degrees (usually 180 degrees) at irregular intervals, giving the hair a spangled appearance. The affected hairs are brittle and break easily; thus, they do not attain a normal length. PT may occur as an isolated phenomenon or with other abnormalities. It has been described in association with many other defects (deafness, intellectual disability, ichthyosis, skeletal deformities) as well as recognizable syndromes (Bazex-Dupré-Christol, Menkes, hypohidrotic ectodermal dysplasia, Bjornstad, and Crandall). For a complete list of syndromes, search Pili Torti in the Online Mendelian Inheritance in Man (OMIM) database: https://www.ncbi.nlm.nih.gov/omim.

PT is usually congenital but may occur in the first and second years of life. The classic type of PT is a diffuse abnormality usually found in association with thin blond hair, occurring alone or as part of an ectodermal dysplasia syndrome. A rare late-onset variant of PT is inherited in an autosomal dominant fashion, mostly in patients with jet-black hair, and is characterized by alopecia of the scalp, face, and body hair that develops after puberty.