Osler's node

Osler's nodes are painful, red, raised lesions found on the fingers, toes, or occasionally on the palms or soles. They are a clinical sign of infective endocarditis, although they can occur in other conditions.

These lesions are caused by immune complex deposition in the small blood vessels of the digits. The immune complexes trigger a local inflammatory response, leading to the characteristic appearance and tenderness. The lesions are typically small, ranging from a few millimeters to a centimeter in diameter.

Osler's nodes are often distinguished from Janeway lesions, another dermatological sign of endocarditis. While both are associated with endocarditis and found on the hands and feet, Janeway lesions are typically painless, macular (flat), and hemorrhagic, and located on the palms and soles. Osler's nodes, in contrast, are typically painful, raised, and found more often on the pads of the fingers and toes.

The presence of Osler's nodes, in conjunction with other clinical findings such as fever, heart murmur, and positive blood cultures, can be important in the diagnosis of infective endocarditis. The nodes typically resolve with treatment of the underlying infection.