Janeway lesion

**Definition:** Janeway lesions are nontender, flat (macular) or slightly raised, erythematous to hemorrhagic lesions, typically 1–5 mm. They are found on the palms and soles, especially the thenar and hypothenar eminences and the plantar surfaces. They are a classic peripheral cutaneous stigma of infective endocarditis (IE).

**Pathophysiology:** Fragments of valvular vegetations break off and embolize to the dermal vasculature. The result is septic microemboli with bacteria, neutrophilic infiltrate, microabscess formation, and small-vessel necrosis and hemorrhage. Because the lesions contain viable organisms, cultures or biopsy may sometimes be positive. This embolic and suppurative mechanism is the key contrast with Osler nodes.

**Associations:** - Classically associated with acute bacterial endocarditis, most often *Staphylococcus aureus*. This is typical of IV drug users with right-sided (tricuspid) disease, though septic emboli there go to the lungs. Janeway lesions can also occur in subacute IE (viridans streptococci). - Part of the Duke criteria. Under the modified Duke criteria, Janeway lesions are a minor vascular phenomenon, along with major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, and conjunctival hemorrhage.

**Janeway lesions vs. Osler nodes (high-yield):** - Janeway lesions are painless, found on the palms and soles, and are macular. They are due to septic emboli (microabscesses) and are a vascular phenomenon in the Duke criteria. - Osler nodes are painful, found on the finger and toe pads, and are nodular. They are due to immune-complex deposition (type III hypersensitivity) and are an immunologic phenomenon in the Duke criteria. - Mnemonic: "Janeway = Jane has No pain" (painless, septic emboli). "Osler = Ouch" (painful, immune complexes).

**Other IE stigmata:** Roth spots (retinal hemorrhages with pale centers), splinter hemorrhages (nail bed), petechiae, new regurgitant murmur, fever, and glomerulonephritis (immune-complex).

**Clinical approach:** Suspect IE when these lesions occur with fever and a murmur, especially in a patient who uses IV drugs or has a prosthetic valve. Obtain at least 3 sets of blood cultures from separate sites before antibiotics, then do a TTE and TEE if needed. Treat with prolonged IV antibiotics (empiric vancomycin for suspected S. aureus/MRSA) and consider surgery for heart failure, abscess, or large vegetations with recurrent emboli.

**Eponym:** Named after Edward Janeway, an American physician (1841–1911).