Massive Aseptic Splenic Abscess as the Presenting Manifestation of Active Lupus Nephritis: A Case Report

Splenic abscesses are uncommon in systemic lupus erythematosus (SLE) and are typically infectious. Aseptic abscesses—sterile purulent collections resulting from immune dysregulation—are exceedingly rare and diagnostically challenging. We report a 25-year-old woman with no prior renal disease who presented with fever, left hypochondrial pain, and edema. Computed tomography imaging revealed a large splenic abscess measuring 12 × 13 × 10 cm. Ultrasound-guided drainage yielded 800 mL of purulent fluid, but bacterial, fungal, and mycobacterial cultures remained negative. Serology indicated active lupus (anti-dsDNA >800 IU/mL, hypocomplementemia), and renal biopsy showed Class IV diffuse lupus nephritis (ISN/RPS 2022). The patient improved with high-dose methylprednisolone followed by cyclophosphamide, and was transitioned to mycophenolate mofetil for maintenance. At 6-month follow-up, she remained asymptomatic with biochemical remission. Aseptic splenic abscess should be suspected in SLE patients with negative cultures and high disease activity, as prompt drainage and immunosuppression can lead to favorable outcomes.