Two autopsy cases of ANCA-associated glomerulonephritis which manifested clinically after contrast medium use

[Case 1] An 81-year-old man was referred to our hospital with dyspnea and bloody sputum. Computed tomography with contrast medium for the evaluation of metastasis of urinary bladder carcinoma had been performed 4 months previously. On admission, his serum creatinine and potassium were 15.3 mg/dl and 6.9 mEq/l, respectively. His chest X ray revealed cardiomegaly, butterfly shadow and interstitial change, indicating congestive heart failure and interstitial pneumonia. His electrocardiogram showed that he was on the brink of cardiac arrest due to hyperkalemia. Mechanical ventilation and hemodialysis were initiated. Myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) was highly positive (321 EU), leading to the diagnosis of MPO-ANCA-associated rapidly progressive glomerulonephritis (RPGN) with interstitial pneumonia. Treatment with pulse methylprednisolone was not effective and he died. Autopsy findings showed crescentic glomerulonephritis, alveolar hemorrhage and interstitial pneumonia with honeycomb formation. [Case 2] A 73-year-old man was referred to our hospital with rapid deterioration of his renal function. He had received a cardiac catheter examination 3 weeks previously. On admission, his serum creatinine was 4.5 mg/dl. His chest X ray showed cardiomegaly and interstitial change. Renal biopsy findings showed crescentic formation in the glomeruli. Moreover, MPO-ANCA was 494 EU, leading to the diagnosis of MPO-ANCA-associated RPGN with interstitial pneumonia. Treatment with pulse methylprednisolone and cyclophosphamide was not effective and he died. Autopsy findings revealed crescentic glomerulonephritis and interstitial pneumonia with honeycomb formation. Here we described two cases of ANCA-associated RPGN complicated by microscopic polyantitis and interstitial pneumonia after the use of contrast medium. The relation between ANCA-associated RPGN and the contrast medium was unclear. However, in the case of rapid deterioration of renal function, MPO-ANCA should be measured even after the use of contrast medium. The complication of lung diseases, especially interstitial pneumonia, should be investigated simultaneously.