Hereditary palmoplantar keratoderma and dermatophytosis in the northernmost county of Sweden (Norrbotten)

Clinical reports of hereditary palmoplantar keratoderma are generally based on a limited number of patients. In 1967 the prevalence in the northernmost county of Sweden (Norrbotten) was shown to be 0.55%. In 1982 it was possible to trace half of the original propositi from that study. Among these families, a severe clinical form with a presumed recessive inheritance could be distinguished. The clinical pictures in relatives of the original propositi were described, and other diseases were listed together with those in patients from previously performed studies. The frequency of dermatophytosis was 36.2%, which was equal to a prevalence of 37.6%. T. mentagrophytes occurred significantly more often and immunological factors, such as increased presence of blood group A, specific dermatophyte IgG antibodies, precipitating antibodies and an immunological in vitro reaction to keratin, supported differences in the distribution of dermatophytes. However, the amount of keratin was considered the most important factor for the affinity of dermatophytes to the palms and soles. A vesicular eruption along the hyperkeratotic border and a mononuclear cell infiltrate were often reported. Such reactions were interpreted as immunological reactions to dermatophytosis. Scaling and fissuring were considered clinical signs of dermatophyte infections and not a part of the originally reported clinical picture. Results of the histopathological study corresponded to previously reported descriptions of the Unna-Thost variety. However, it has recently been reported that the histopathological picture of this variety was based on histopathological features of epidermolytic palmoplantar keratoderma. The existence on the Continent of the Unna-Thost variety was therefore questioned. Histopathological features of epidermolytic palmoplantar keratoderma were not found in the County of Norrbotten and the designation "Diffuse HPPK type Norrbotten" has therefore been proposed. The histopathological picture of the presumed recessive variety did not differ from that of the dominant variety but ultrastructural characteristics differentiated it from Mal de Meleda and the dominant variety. It was therefore concluded that a new variety with a presumed recessive inheritance was found.