The dominant form of hereditary palmoplantar keratoderma in the northernmost county of Sweden (Norrbotten).

The frequency of autosomal dominant inherited palmoplantar keratoderma (HPPK) in the northernmost county of Sweden (Norrbotten) is 0.55%. Histopathological examination of 91 biopsies from patients with the dominant form of HPPK revealed no case of epidermolytic PPK. This finding is in contrast to the results of a re-examination of descendants of the original family published by Thost which showed the characteristic features of epidermolytic PPK, and re-evaluation of biopsies from other families has shown that it is the most frequent type. The existence of PPK type Unna-Thost in relation to epidermolytic PPK and to HPPK of the northernmost county of Sweden will be discussed. At the same time a revision of designation of this type is proposed. A dermo-epidermal mononuclear cell infiltrate belongs to the classical description of PPK Unna-Thost. It was shown that this cell infiltrate occurs significantly more often in patients with HPPK and dermatophytosis. Relapsing vesicular eruptions along the hyperkeratotic border are a clinical sign of the severity of dermatophyte infections. Such spongiotic vesicles together with a mononuclear cell infiltrate should be considered as eczematous reaction to dermatophytosis.