ACQUIRED, PARTIAL TRICHOTHIODYSTROPHY

The current classification of hair shaft dysplasias differentiates bet ween ''non-specific'' and ''specific'' dysplasias. Among the latter, t hough, there are some which can only be considered as ''native'' or '' totally specific'' dysplasias when there is an underlying disease that causes such alteration (e.g, monilethrix, pill multigemini and pill a nnulati), and other kinds of dysplasias which are considered to have ' 'their own particular identity'' and which may concur in various diffe rent syndromes (e.g. trichorrhexis nodosa, pill torti and pill canalic uli). Until now, hairs showing alternating bright and dark zones were always related to trichothiodystrophy (TTD) and, therefore, considered to be a ''native or totally specific'' hair shaft dysplasia. After th e presentation of this case of ''pseudo-TTD'' or ''acquired TTD'', we believe that this particular condition should be diagnosed as a ''dysp lasia with its own identity'' from now onwards.