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.