Pili trianguli et canaliculi: a distinctive hair shaft defect leading to uncombable hair.

Uncombable hair syndrome refers to a clinical disorder characterized by scalp hairs arranged in bundles in all directions that resist to brush and comb. Several entities may lead to spun-glass hair. As a rule the syndrome becomes obvious during the first years of life. The hair is normal in quantity, and increased fragility is not a common feature. The hair is often dry with silvery blond color. Under the light microscope the hairs may appear normal. Scanning electron microscopy shows a characteristic triangular, kidney- or heat-shaped diameter with typical longitudinal canalicular deformation. We present a 9-year-old girl with the typical clinical features of pili trianguli et canaliculi. Investigation by scanning electron microscopy confirmed the diagnosis. In addition the girl had enamel defects of the teeth and nail abnormalities that classify for a subtype of ectodermal dysplasia.