Allergic granulomatosis (Churg-Strauss syndrome): pulmonary and renal morphologic findings

The pulmonary histopathology of four cases of allergic granulomatosis (Churg-Strauss syndrome) was reviewed. Renal tissue was also studied in one case. The patients were young and most presented with asthmatic symptomatology. They showed marked peripheral blood eosinophilia, and had fluffy nodular pulmonary infiltrates by chest x-ray. Serum IgE was elevated in the one patient in whom it was obtained. The lung tissue in all cases showed necrotizing giant-cell vasculitis, interstitial and perivascular granulomas, and eosinophilic pneumonia-like areas. These microscopic features distinguish allergic granulomatosis from other forms of pulmonary eosinophilia or vasculitis. Renal tissue showed necrotizing granulomatous vasculitis and interstitial eosinophilic nephritis, without evidence of glomerulonephritis. Electron-microscopic study of one lung biopsy and of the renal tissue demonstrated tissue eosinophilia and, in lung, a granuloma. There was no evidence of vascular or glomerular electron-dense deposits. These findings are discussed in the light of possible pathogenetic mechanisms of allergic granulomatosis.