A 66‐year‐old white woman with a history of biopsy confirmed class III systemic lupus erythematosus (SLE) nephritis presented with shortness of breath, fatigue, myalgias, and recurring rash on her right lower extremity. Past medical history included hypertension. Medications included amlodipine and prednisone. She was a nonsmoker and nondrinker. On examination, lungs were clear to auscultation, right lower extremity revealed α 5 × 8 cm erythematous, painful, palpable purpura. Vitals signs where within normal limits. Notable serum studies were: creatinine 1.85, urea 55, white blood cell count 16.6, platelets 255, hemoglobin 12.8. Her chest radiograph showed bilateral air space opacities. Urinalysis was positive for a large amount of blood and trace amounts of protein. Blood and urine cultures were negative. Skin biopsy revealed small‐vessel leukocytoclastic vasculitis. The following morning, she decompensated, requiring emergent intubation. Follow‐up chest x‐ray showed progression of bilateral alveolar infiltrates, and CT chest demonstrated patchy bilateral infiltrates. Bronchoscopy confirming suspicion of diffuse alveolar hemorrhage, and endoscopy showed diffuse erosive gastritis. Immune serology was negative for antiglomerular basement membrane and double‐stranded DNA, but positive for antinuclear antibodies, with a peri‐nuclear pattern on immunofluorescence (pANCA). Myelo‐peroxidase (MPO) specificity was confirmed by quantitative ELISA at a concentration of 100 units, thus confirming our suspicion of microscopic polyangiitis (MPA). She underwent 11 consecutive treatments of plasma exchange along with 1 g of intravenous cyclophosphamide and intravenous methylprednisolone. Corticosteroids were eventually changed to 60 mg of oral prednisolone after 10 days. She required mechanical ventilation for a total of 12 days and received 2 units of blood for ongoing hemorrhage. Over the next 6 months, our patient received treatment with monthly pulsed cyclophosphamide and prednisolone. Monitoring of the pANCA titer, C‐reactive protein concentration, and clinical state were maintained, and the patient returned to her baseline renal function and respiratory status. She has been continued on mycophenolate mofetil to prevent relapse of lupus nephritis.
This is the first reported case of microscopic polyangiitis in the setting of established SLE nephritis. Our case exemplifies the importance of a methodical approach to an extensive list of differential diagnoses. The main clinic clues to the alternative diagnosis of renal–pulmonary syndrome were diffuse alveolar hemorrhage and erosive gastritis. A positive pANCA and high anti‐MPO titers without upper respiratory involvement strongly support our diagnosis.
We illustrate a unique case of microscopic polyangiitis manifesting as a renal–pulmonary syndrome in the setting of SLE nephritis. MPA may present with myriad symptoms, thus distinguishing it from other vasculitides may be a challenge.
V. Faridani ‐ none; K. Khosa ‐ none; J. Hayes ‐ none; M. Mathew ‐ none