Background: Tiger tail banding under polarizing light microscopy and hair shaft abnormalities are associated with trichothiodystrophy (TTD), a rare disorder with a wide spectrum of clinical presentations.
Objective: To characterize the frequency, specificity, and extent of tiger tail banding and hair shaft abnormalities in the spectrum of TTD patients.
Methods: We developed a standardized procedure for microscopic hair examination and studied hairs from 14 TTD and 4 xeroderma pigmentosum (XP)-TTD patients for tiger tail banding and hair shaft abnormalities. For comparison we examined hairs from 173 control donors consisting of 15 normals, 13 XP patients, 11 family members of XP or TTD patients, 101 patients with various cornification disorders, and 33 leukodystrophy patients. Amino acid analysis performed on hair from the TTD and XP-TTD patients showed low sulfur content.
Results: Using a rotating microscope stage, all hairs in each TTD sample showed tiger tail banding under polarized light in association with a variety of hair shaft abnormalities (trichoschisis, trichorrhexis nodosa-like defects, surface irregularities, and ribboning). None of the control hairs showed tiger tail banding, and 5 of 173 controls had weathering hair shaft abnormalities.
Conclusions: In patients with clinical features suggestive of TTD, tiger tail banding seen in all hairs with polarizing microscopy, in conjunction with certain hair shaft abnormalities, provides a reliable diagnostic test.