Scanning Electron Microscopy of the Inner and Outer Aspects of Tiger Tail Hairs.

Background: Tiger tail hairs, Morse hairs or pili annulati is a nonsyndromic hair shaft disorder, characterized by alternating light and dark bands along the hair shaft. Methods: The outer surface and the inner structure of longitudinally cut tiger tail hairs were examined with scanning electron microscopy. Results: Hair specimens of five affected individuals showed small surface undulations with "curtain-like" folding of the hair cuticula (microcanaliculi). In the inner surface cord-like linear structures with serpiginous, tortuous traject were seen, associated with some cavities. Conclusions: These findings suggest that this condition is due to some deficient protein synthesis/arrangement, not only due to cavities in the hair cortex. The term Tiger tail hair is a descriptive clinical term of little scientific rigor. This disorder has been reported mainly as pili annulati; however, rings are not observed. In analogy to pili canaliculi, in which well-formed grooving is observed in the hair surface, we suggest the term pili microcanaliculi to describe this condition, based in the ultrastructural findings.