In the February issue of the Archives, Brusasco et al1 reported a case of trichothiodystrophy in which findings of hair microscopic examinations changed in the first month of life, with the development of the "tiger tail" appearance on polarized light microscopic examination. The authors make several points that would be helpful to put in a more general context.
Although the tiger tail appearance may suggest a hair disorder, it is a relatively common finding in the hair of healthy infants and those with no specific disease.2 Conversely, it is not seen in neonates, as demonstrated in a recent study3 where 20 premature newborns (mean gestational age, 36 weeks) underwent regular and polarized transmitted light microscopic examinations of cut and plucked hair samples from the parietal scalp. These samples revealed markedly homogeneous characteristics on polarized light microscopic examination, with hairs demonstrating a gold, blue, or brown hue, with
Berker DD. 'Tiger Tail' Pattern on Polarized Hair Microscopic Examination Is Found in Healthy Infants. Arch Dermatol. 1997;133(10):1313. doi:10.1001/archderm.1997.03890460139023