ANCA negative pulmonary renal syndrome with pathologic findings of thrombotic microangiopathy

Thrombotic microangiopathy (TMA) is characterized by aggregation of platelets in the renal and/or systemic circulation, thrombocytopenia and intravascular hemolysis. The syndrome classically spares the lung. The term pulmonary-renal syndrome describes a number of diseases in which pulmonary hemorrhages and glomerulopathy coexist. We report a 44-year-old man admitted to hospital because of chronic unexplained fever. Six days after admission he developed hemoptysis, respiratory distress and biochemical evidence of acute renal failure. High-resolution computed tomography scan of the chest demonstrated alveolar hemorrhages. The patient developed hypoxia and was shifted to the intensive care unit to be supported by mechanical ventilation. He also received two sessions of continuous veno-venous hemodiafiltration. Kidney biopsy revealed pathological findings of TMA. Serology for anti-neutrophil cytoplasmic antibodies, anti-cardiolipin antibodies and anti-glomerular basement membrane antibodies was negative. The patient was treated with pulse steroids followed by prednisolone with mild improvement. Seven days later, his condition deteriorated with an increase in serum creatinine and pulmonary hemorrhages. His hemoglobin level dropped and he developed features of intravascular hemolysis. A diagnosis of TMA was made and treatment with plasma exchange was initiated. The patient showed dramatic improvement and was discharged in good condition. He remained in remission throughout his subsequent follow up. TMA should be considered in the differential diagnosis of pulmonary renal syndromes, and can be successfully managed by corticosteriods combined with plasma exchange.