Extra‐palmoplantar skin lesions of palmoplantar keratoderma with deafness caused by a mitochondrial mutation

Abstract

Dear Editor, Palmoplantar keratoderma (PPK) with deafness is largely caused by a mutation in GJB2 encoding connexin 26.1 Contrarily, it is also known that PPK with sensorineural deafness is maternally inherited and caused by a mitochondrial mutation m.7445A>G, mitochondrial PPK (MPPK).2 In MPPK, sensorineural deafness occurs from infancy to age 5 and palmoplantar lesion gradually develops between the ages of 5 and 15 years.3,4 Although the extrapalmoplantar manifestations of the disease are not clear, we recently reported a case of extrapalmoplantar skin lesions caused by pregnancy.5 Here, we report two patients of the same family who presented only extrapalmoplantar lesions, and identified the m.7445A>G mutation. Case 1 was a 5yearold girl who visited our department for hyperkeratotic erythema which had started a few months prior. Her mother had PPK with deafness caused by the m.7445A>G mutation (Figure 1a). Upon physical examination, hyperkeratotic plaques were observed on her left knee and the left lateral aspect of her first toe (Figure 1b,c). The lesion on her knee had been formed after a trauma. PPK and deafness were not observed. We initially treated her with topical steroids, but there was no improvement in the lesions. She