Pathogenesis of Osler's nodes.

Four patients in whom endocarditis had been verified at autopsy had the pathogenic organism isolated from aspirates of Osler's nodes. In three cases the responsible organism was identified in Gram stains made from aspirates. The etiologic agent was Staphylococcus aureus in three cases and Candida albicans in one case. Histologic examination of an Osler's node from one of the patients with S. aureus endocarditis showed a microabscess in the papillary dermis together with microemboli in nearby dermal arterioles. Workers previously have interpreted similar histologic findings as consistent with perivasculitis resulting from an immunologic reaction to the pathogenic organism. The present findings support Osler's original contention that the skin lesions that bear his name are "in all of probability caused by minute emboli".