A 76–year–old women presented with two days of hemoptysis, dyspnea on exertion, and fatigue stating she coughed up two cups of blood per day. She had no previous history or exposure to tuberculosis, and had never been homeless or incarcerated. She denied tobacco or drug use, any fever, chills, or sick contacts. She had recently engaged in a work–up for chronic joint pains & weight loss at an outside facility. A rheumatologic disorder was suspected, but no final diagnosis could be made, and she ceased seeing her primary care provider. On physical exam, she was breathing comfortably and spoke in full sentences; nares and oropharynx were clear, heart sounds were normal and there were no murmurs. Breath sounds were diminished with crackles bilaterally. There was bilateral pitting edema in the lower extremities. Her blood urea nitrogen was 67 mg/dL and creatinine was 5.6 mg/dL. Hemoglobin was 7 g/dL with normal platelet count. Her sedimentation rate was elevated at 111 mm/h. Based on a normal fractional excretion of sodium, testing for intrinsic renal disease was ordered. Her glomerular basement membrane antibody was elevated at 35 units, the ANA titer was 1:40 with a speckled pattern, the P–ANCA titer was 1:160, the MPO–ANCA titer was 22.4 U/mL. Her C–ANCA, PR3 ANCA, and a compliment level were normal. Multifocal consolidative and ground–glass opacities were present bilaterally with multiple nodules on chest computed tomography.
Although rheumatologists play a central role in the ultimate management of the vasculitities, it is usually the hospitalist who establishes the initial diagnosis and executes appropriate initial management. It is important for hospitalists to recognize the historical, examination and laboratory patterns of the common vasculitities. Microscopic polyangiitis (MPA), along with granulomatous polyangiitis, Churg–Strauss syndrome, primary pauci–immune necrotizing and crescentic glomerulonephritis, are anti–neutrophil cytoplasmic antibody (ANCA) vasculitides. The pathogenic antibody in microscopic polyangiitis is specific to myeloperoxidase (MPO). Our patient’s signs and symptoms of weight loss, dyspnea, fatigue, acute kidney failure, and hemoptysis are classic for microscopic polyangiitis.
MPA was universally fatal until the use of cytotoxic treatment, now the ten year survival rate is 60–80% with the mortality rate highest in the first month of diagnosis. Relapse occurs in nearly a 30% of patients. Treatment should focus on decreasing B cells, removing antibodies, and decreasing inflammation. Cyclophosphamide, rituximab, mycophenolate mofetil, azathioprine, steroids, and plasmapheresis have been used for treatment in MPA. Prophylactic use of trimethoprim–sulfamethoxazole should be initiated, as up to 10% of patients will have Pneumocystis jiroveci pneumonia. Early detection of microscopic polyangiitis carries a fair prognosis, and thus should be considered in a patient with constitutional symptoms not explained by other diagnosis.