A consideration of the differences between a Janeway's lesion and an Osler's node in infectious endocarditis.

Janeway's lesions and Osler's nodes are regarded as excellent clues to the diagnosis of infectious endocarditis; however, very few physicians have actually witnessed these findings, and there is some confusion in distingushing between the two. This article concerns a patient with infectious endocarditis due to Diplococcus pneumoniae, who had tender vesicular lesions thought to be Osler's nodes and a nontender erythematous nodule on the foot compatible with a Janeway's lesion. The original comments by William Osler and Edward Janeway are presented, and the literature following their descriptions is reviewed. It is concluded that the only essential diagnostic difference between the two is the tenderness that is associated with an Osler's node but not with a Janeway's lesion.