A 5-year-old boy with a history of hydrocephalus, cortical and cerebellar atrophy, hypospadias, cryptorchidism, psychomotor retardation, renal hypoplasia, high myopia and nystagmus presented to the dermatology department with sparse, dry and brittle hair and ichtyosis sparing the palms and soles. His hair did not grow and had never been cut. He did not have photosensitivity.
On light microscopic examination, the hair strands appeared normal, but upon setting the polarized light filter and rotating it slowly, alternating light and dark transverse bands could be seen (Fig. 1 and Appendix A, video).
This key finding led to the diagnosis of trichothiodystrophy, a hair dysplasia that is part of a complex neuroectodermal syndrome.