Osler's nodes and Janeway lesions.

The pathogenesis of Osler's nodes and Janeway lesions remains a mystery despite vigorous debate over the last 113 years. They are given great emphasis among the clinical signs of bacterial endocarditis but are seldom seen in practice. Two cases of subacute bacterial endocarditis are presented. A 66-year-old woman with Bartonella henselae endocarditis developed Osler's nodes on the hands postoperatively, and a 23-year-old man with Streptococcus oralis endocarditis developed tender macules with an appearance suggestive of Janeway lesions on one heel. The dermatopathology was similar in the two cases, consisting of a leukocytoclastic vasculitis without micro-abscess formation or visible organisms. Although the appearance is usually consistent, it is not always possible to distinguish Osler's nodes from Janeway lesions based purely on clinical presentation. Furthermore, the histology of both clinical signs can look similar. Further reports are needed before more firm conclusions can be drawn, however, it may be that the histological appearance of Osler's nodes and Janeway lesions is primarily determined by the nature of the causative organism, while the clinical appearance may be determined by anatomical site.