A 45-year-old man with subacute bacterial endocarditis has small, tender nodules on the pulp of his fingers along with painless erythematous macules on his palms. Biopsy of a palmar macule shows microabscesses with embolic bacteria in dermal vessels. Which statement correctly matches these findings?
- A Both the nodules and the macules are septic embolic phenomena
- B The nodules are septic microemboli while the macules reflect immune complex vasculitis
- C The nodules result from immune complex deposition while the macules are septic microemboli ✓
- D Both lesions are mediated by type III hypersensitivity reactions
Correct answer: C. The nodules result from immune complex deposition while the macules are septic microemboli
Explanation
Osler nodes are painful nodules on finger or toe pads produced by immune complex-mediated microvasculitis, whereas Janeway lesions are painless macules on palms or soles formed by septic microemboli lodging in dermal vessels, which explains the microabscesses seen on biopsy here. Roth spots and glomerulonephritis also arise through immune complex mechanisms. Confusing the two is a classic exam trap: pain plus tenderness points to immune mediation, painlessness plus a biopsy showing bacteria indicates embolic infection.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.