An uncommon cause of fever in the elderly: late-onset systemic lupus erythematosus.

Infections, tumors and multisystem disease are common causes of fever of unknown origin (FUO) in the elderly. Late-onset systemic lupus erythematosus (LO-SLE) is a very rare cause of FUO in elderly patients. Serositis and musculoskeletal manifestations are common, but fever as an initial manifestation in LO-SLE is rare. We present two patients with LO-SLE who manifested fever as an initial symptom. Fever was the only symptom for 2 months in the first case and for 3 months in the second. In conclusion, in geriatric patients who have fever, LO-SLE should be considered in the differential diagnosis.