We thank de Berker for the interesting comments. His remarks that the "tiger tail" pattern of the hair shaft demonstrated on polarized light microscopic examination is not pathognomonic for trichothiodystrophy (TTD) and that amino acid analysis is pivotal for a correct diagnosis were voiced in our letter.
In our practice, we use the hair shaft examination with polarized light microscopy as a diagnostic aid only in patients clinically suspected to have TTD. All our cases of TTD showed the diffuse tiger tail pattern in most of the hair shafts, and we have never found the tiger tail pattern in patients in whom the diagnosis of TTD was excluded. We routinely obtain hair samples from the frontal, temporal, and occipital regions. The hair shaft of the 2 patients described in our original letter1 showed a similar pattern in all 3 sites sampled.
However, the peculiarity of our report was the
Brusasco A, Restano L, Cambiaghi S, Tadini G. Unilesional Mycosis Fungoides or Lymphomatoid Keratosis?-Reply. Arch Dermatol. 1997;133(10):1313-1314. doi:10.1001/archderm.1997.03890460139024