The cat did it: erythema nodosum and additional atypical presentations of infection in immunocompetent hosts.

A healthy patient presented with painful skin lesions on the anterior surface of her legs. Erythema nodosum was diagnosed but all the usual causes were ruled out. The finding of bilateral enlarged axillary lymph nodes with necrosis and granulomas led to the diagnosis of infection, an unusual cause of erythema nodosum. Imaging also revealed splenomegaly and small para-aortic lymph nodes. Up to one quarter of the patients with cat-scratch disease present atypically, a considerably higher prevalence than previously reported. A comprehensive review of the literature (PubMed, since inception, all languages) revealed a remarkable array of unusual presentations which are summarised and briefly discussed.