Uncombable hair (cheveux incoiffables, pili trianguli et canaliculi) syndrome: Brief review and role of scanning electron microscopy in diagnosis

Uncombable hair syndrome was first described some 3 decades ago as "cheveux incoiffables" and is also known as spun-glass hair and pili trianguli et c analiculi Both inherited (autosomal dominant and recessive with variable le vels of penetrance) and sporadic forms of uncombable hair syndrome have bee n described, both being characterized by scalp hair that is impossible to c omb due to the haphazard arrangement of the hair bundles. A characteristic morphologic feature of hair in this syndrome is a triangular to reniform to heart shape on cross-sections, and a groove, canal or flattening along the entire length of the hair in at least 50% of hairs examined by scanning el ectron microscopy. Most individuals are affected early in childhood and the hair takes on a spun-glass appearance with the hair becoming dry, curly, g lossy, lighter in color, and progressively uncombable. Only the scalp hair is affected. Several conditions are associated with uncombable hair, such a s ectodermal dysplasia. retinal dysplasia/pigmentary dystrophy, juvenile ca taract, digit abnormalities, tooth enamel anomalies, oligodontia, and phala ngoepiphyseal dysplasia. Other syndromes with hair abnormalities may also m imic uncombable hair syndrome clinically and these include, Rapp-Hodgkin ec todermal dysplasia; loose anagen hair syndrome; ectodermal dysplasia, ectro datyly, cleft lip/palate (EEC) syndrome; and familial tricho-odonto-onchyia l ectodermal dysplasia with syndactyly. Unlike other conditions with an unc ombable hair component, uncombable hair syndrome alone (cheveux incoiffable s, pili trianguli et canaliculi) is not associated with physical, neurologi c, or mental abnormalities. In most cases of uncombable hair syndrome, the hair is grossly abnormal in infancy and early childhood, but may have impro ved manageability later in life. Scanning electron microscopy of hair sampl es provides definitive evidence for diagnosis of clinically suspected uncom bable hair syndrome and eliminates other hair abnormalities from the differ ential diagnosis.