Skin lesions in human yersiniosis. A histopathological and immunohistological study

Various types of skin manifestations of human yersiniosis were examined with routine histological and immunohistological methods. The biopsy material consisted of sixteen cases of erythema nodosum, eight cases of erythema multiforme, and one case of erythema figuratum. The principal histopathological changes in erythema nodosum were septal or diffuse, mild panniculitis and in seven cases also necrotizing vasculitis in small, medium-sized or large arteries. Perivascular lymphocytic infiltration without vasculitis was the most prominent feature in erythema figuratum. By using a polyvalent conjugate, immunoglobulins in vessel walls in the dermis were found in two cases of EM. The rapid course of the skin eruptions and the frequency of necrotizing vasculitis in arteries fit the changes seen in an experimental Arthus reaction, in which necrotizing vasculitis is followed by lymphocytic inflammation consistent with a delayed type of reaction.