Early immunopathological diagnosis of ichthyosis with confetti in two sporadic cases with new mutations in keratin 10.

Ichthyosis with confetti (IC) is a severe non-syndromic ichthyosis due to heterozygous mutations in the KRT10 gene. The disease manifests at birth with erythroderma and scaling and is characterised by the gradual development of numerous confetti-like spots of normal skin. Diagnosis of IC is frequently delayed until adolescence or even adulthood. We report 2 young children who were first diagnosed as having congenital ichthyosiform erythroderma. However, the development of thick, confluent hyperkeratotic plaques together with the histopathological finding of keratinocyte vacuolisation in the suprabasal epidermis evoked IC. Immunofluorescence analysis showed a highly reduced keratin 10 expression within the cytoplasm of suprabasal keratinocytes and its characteristic mislocalisation to the nuclei. The diagnosis was confirmed by the identification of 2 previously unreported mutations in intron 6 and exon 7 of KRT10. Careful clinical examination then showed the presence of the first spots of normal skin in both patients at the age of 2.5 and 5 years, respectively. These cases point to the usefulness of immunofluorescence analysis of keratin 10 expression for an early diagnosis of IC.