A 38-year-old pregnant woman with hemoptysis and acute renal failure. Microscopic polyangiitis.

and dysmorphic red blood cell casts. A quantitative serum pregnancy test was positive. Bronchoalveolar lavage retrieved blood-tinged fluid, numerous red blood cells and hemosiderin-laden macrophages but few neutrophils. Microbiology studies for bacteria, mycobacteria and fungi in the bronchoalveolar lavage fluid were negative. Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) with specificity for myeloperoxidase (MPO) were positive (5.5 U/ml, normal ! 0.4). Serologies for antiglomerular basement membrane, antinuclear antibodies, C-ANCA, antiproteinase 3 (PR3-ANCA), antinuclear antibodies, antiphospholipid panel, and HIV were negative.