"Nagashima-type" keratosis as a novel entity in the palmoplantar keratoderma category.

Background: "Nagashima-type" keratosis is characterized by transgressive and nonprogressive palmoplantar keratoderma (PPK) with an autosomal recessive trait. Because its clinical manifestations are similar to but milder than those of mal de Meleda, it was originally described as a mild form of Meleda-type PPK. Since then, about 20 cases have been reported in the Japanese-language literature. However, to our knowledge, no cases have been reported from countries other than Japan, presumably because Nagashima-type PPK was not recognized as a distinct entity. It is essential to describe the characteristics of this disease in the English-language literature.

Observations: A 17-year-old boy presented with transgressive, hyperhidrotic, erythematous, and hyperkeratotic lesions on his palms and soles that had developed when he was an infant and had progressed until 2 to 3 years earlier. His family history revealed no similar disorders. The symptoms and clinical course were typical for Nagashima-type PPK. A genetic study was performed to search for a mutation in the SLURP1 gene, which is responsible for mal de Meleda, but no mutations were detected in the exon or intron sites of SLURP1. Conclusion The results of the present genetic study suggest that Nagashima-type keratosis is a novel entity of PPK and is distinct from mal de Meleda.