Osler's nodes are painful, red, raised lesions found on the hands and feet. They are associated with a number of conditions, including infective endocarditis, and are caused by immune complex deposition. Their presence is one definition of Osler's sign.^[1]

Osler's nodes result from the deposition of immune complexes.^[2] The resulting inflammatory response leads to swelling, redness, and pain that characterize these lesions.

The nodes are commonly indicative of subacute bacterial endocarditis.^[3] 10–25% of endocarditis patients will have Osler's nodes.^[4] Other signs of endocarditis include Roth's spots and Janeway lesions. The latter, which also occur on the palms and soles, can be differentiated from Osler's nodes because they are non-tender.^[2]

Osler's nodes can also be seen in

• Systemic lupus erythematosus
• Marantic endocarditis
• Disseminated gonococcal infection
• Distal to infected arterial catheter

Osler's nodes are named after Sir William Osler who described them in the early twentieth century.^[5][6] He described them as "ephemeral spots of a painful nodular erythema, chiefly in the skin of the hands and feet."^[7]