[Collodion baby with neonatal signs of trichothiodystrophy misdiagnosed as Netherton syndrome: reassessment of a previous diagnostic error].

BACKGROUND: Reassessment of a previously published case report allowed correction of a misdiagnosis: a neonatal aspect of collodion baby with pilar dystrophy is evocative of trichothiodystrophy and not Netherton syndrome. Other than this published erroneous case report, there have been no other publications concerning Netherton syndrome mentioning this neonatal collodion baby status. It may be clearly stated that Netherton syndrome never begins with collodion baby status.

PATIENTS AND METHODS: The re-examined case concerned a girl with collodion baby syndrome presenting pilar dystrophy. At 2 years, an inaccurate diagnosis of Netherton syndrome was made despite the fact that the pilar dystrophy involved trichorrhexis nodosis with ichthyosis vulgaris. At 8 years, 13 years and 17 years, the diagnosis of trichothiodystrophy was posited in the presence of tiger-striping of the hair visible in polarised light together with low capillary cystine at only 51 p. 100 of the normal level. The phenotype obtained comprised ichthyosis, pilar dystrophy, low IQ and stunted growth of at least two standard deviations despite tall parents. There was no evidence of photosensitivity.

DISCUSSION: The state of baby collodion may or may not herald trichothiodystrophia. A review of 72 articles containing a clinical description of signs at the onset of trichothiodystrophy showed a relationship in 22 cases between this condition and collodion baby syndrome. The collodion baby phenotype is of moderate intensity with little or no facial dysmorphia. Microscopic examination of hair is alone able to orient diagnosis towards trichothiodystrophy. Microscopic examination of the hair with inspection under polarised light is essential to confirm an aetiological diagnosis of collodion baby. Collodion baby syndrome never leads to Netherton syndrome. In some cases, however, it may herald trichothiodystrophy.