[Yersinia exanthema].

Yersinia is an enterobacterium that causes acute enterocolitis, pseudoappendicitis and sepsis. Some patients suffer from post-infectious immunopathological complications, such as erythema nodosum and yersinia arthritis, which are well known. Less information exists concerning the erythema multiforme-like yersinia exanthema, which is a distinctive dermatological disorder with target lesions localized predominantly on the neck, shoulders and arms. These lesions, which may be smaller but often are larger than the iris lesions in conventional erythema multiforme, tend to coalesce into plaques and reveal a papulovesicular component at their periphery. In our cases the exanthema was associated with a conjunctivitis, especially of the nasal part of the conjunctiva. This exanthema can be induced by yersinia enterocolitica, serotype O-3 and type O-9, at least in Europe, whereas serotype O-8 prevails in North America. The most helpful diagnostic criteria are serological data. However, it is crucial to remember that Widal's agglutination reaction gives rise to high titres, whereas the results of the complement-fixation test are often not reliable.