[Pachyonychia congenita. Presentation of a case and histological-histochemical findings]

We report on two cases of pachyonychia congenita, Jadassohn-Lewandowsky type, in a father and daughter. Histopathological examination revealed thickened, aggregated bundles of tonofilaments and an increased number of atypical keratohyalin granula, which is suggestive of an altered keratinization. Immunohistological staining with antibodies to cytokeratins (A45-B/B3, A51-B/H4, A53-B/A2, RPN 1161) was unchanged. Filaggrin could not be detected. Basal cells immunoreactive for calmodulin were markedly reduced or even absent in the rete ridges. Staining with a monoclonal antibody against Ki67 made epidermal cell hyperproliferation seem unlikely. The epidermal lectin binding was normal. C3 was detectable in vessel walls mainly of the stratum reticulare. The findings are discussed with reference to pachyonychia pathogenesis.