SUMMARY: Trichothiodystrophy (TTD) is a rare group of autosomal recessive disorders of DNA repair unified by the presence of sulfur-deficient brittle hair. We report a 3-year-old boy with classic clinical features of TTD, including ichthyosis, alopecia, developmental delay, and tiger-tail banding of the hair shaft on polarizing microscopy. Brain MR imaging showed both diffuse dysmyelination and osteosclerosis, findings that, in combination, may be specific for TTD.T richothiodystrophy (TTD), a rare group of autosomal recessive disorders of DNA repair with a wide range of phenotypic expression, is unified by the presence of sulfur-deficient brittle hair.1,2 Many terms have been proposed to subcategorize patients by groups of clinical features. The acronyms PIBIDS, IBIDS, and BIDS stand for various combinations of (in order) Photosensitivity, Ichthyosis, Brittle hair, Intellectual impairment, Decreased fertility, and Short stature, 1 whereas the term "Tay Syndrome" refers to TTD with ichthyosis.2 We present the case of a child with TTD and MR imaging findings of dysmyelination and central osteosclerosis.
Case ReportA 3-year-old African-American boy presented for evaluation of failure to thrive, global developmental delay, and ichthyosis. Birth history was significant for an induced vaginal delivery at 37 weeks' gestational age for maternal pre-eclampsia and prolonged maternal morning sickness. At birth, a collodion membrane was noted, and his weight was 2268 g. He spent 4 days in the neonatal intensive care unit with hypothermia and severely cracked skin. His mother stated that his skin has improved with time, but peeling, dryness, and scaling persist. He also sunburns easily. MR imaging of the brain at birth was reported to be normal. He had no subsequent hospitalizations and no history of seizure. Developmental history was notable for sitting when placed by 1 year, pulling to stand by 2 years, and first words at 18 months. He had not yet taken any steps.Physical examination was notable for microcephaly, low-set and posteriorly rotated ears, hypoplastic nails, sharpened teeth, and cryptorchidism. Ichthyosis primarily over the proximal upper extremities, chest, and back was noted. Neurologic examination was grossly normal with the exception of tight hip abductors. Ophthalmologic examination demonstrated horizontal conjugate nystagmus.Focused dermatologic examination revealed thin, sparse hair and eyebrows, with hair loss over the frontal scalp. He had rounded fingernails and toenails and plaquelike scale over the abdomen, chest, and back, with minimal scaling of the arms, legs, and face. Hair samples demonstrated tiger-tail banding under polarizing microscopy, consistent with TTD (Fig 1).MR imaging of the brain showed diffuse, severely increased T2 signal intensity in the supratentorial white matter, with relative preservation of the cerebellar white matter, consistent with dysmyelination (Fig 2). There was diffuse hypointensity in the calvarial marrow on T1-weighted images, consistent with osteosclerosis. No diff...