A young woman with systemic lupus erythematosus and extensive mesenteric vasculitis involving small and medium vessels

History of the present illness The patient had 2 recent hospital admissions. Two months prior to her current presentation, she presented to the emergency department with a tooth abscess for which she underwent incision and drainage, and received a 1-week course of penicillin. One week later, she was admitted with a fever of 40.8°C and was noted to have tooth decay on panoramic radiographs without evidence of an abscess. She was treated with intravenous vancomycin and piperacillin tazobactam for 48 hours and then switched to oral clindamycin. Because of her elevated international normalized ratio (INR), she was unable to undergo tooth extraction prior to discharge. Two weeks later, she was readmitted with 4 days of recurrent fevers, malaise, diffuse arthralgias, and increased dyspnea with minimal exertion. Previous lupus exacerbations were characterized by arthralgias, rash, and hemolytic anemia. On this admission, laboratory evaluation revealed leukocytosis, worsening anemia and thrombocytopenia, creatinine of 0.7 mg/dl, alkaline phosphatase of 127 units/liter (normal value 111), spot urine proteinto-creatinine ratio of 1.47 (prior 1.1), low C3 and C4, and an increase in her double-stranded DNA by enzyme immunoassay from 120 to 768 IU/ml (normal value 30). She was empirically treated with vancomycin and piperacillin tazobactam given her recent tooth infection. The elevated alkaline phosphatase level prompted an abdominal ultrasound that showed multiple small hypoechoic areas in the spleen. An extensive infectious evaluation, including blood cultures, fungal serologies, knee arthrocentesis, magnetic resonance imaging of the lumbar spine, transthoracic and transesophageal echocardiograms, and computed tomography of the chest, abdomen, and pelvis, was negative. Her viral serologies were also unremarkable, other than evidence of IgG seropositivity for cytomegalovirus (CMV) with a negative viral load, consistent with prior exposure. Despite broad-spectrum antibiotics, she remained febrile. Her baseline prednisone dose of 12.5 mg was increased to 60 mg daily for possible lupus flare, after which she defervesced within 48 hours. Her thrombocytopenia was thought to be secondary to SLE-related idiopathic thrombocytopenic purpura because it resolved with high-dose steroids and intravenous immunoglobulin. She was discharged home 11 days after admission. The patient remained afebrile for 1 week at home. During this period she developed new-onset progressive upper abdominal pain with meals lasting 20–30 minutes. She denied associated constitutional symptoms, diarrhea, hematochezia, or melena.