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.