Churg-Strauss syndrome with severe granulomatous angiitis and crescentic glomerulonephritis, which developed during therapy with a leukotriene receptor antagonist.

A 77-year-old Japanese female developed Churg-Strauss syndrome (CSS), showing fever and numbness in bilateral hands. She was being treated for bronchial asthma with combination inhalant of corticosteroid with beta(2)-agonist, and an oral leukotriene receptor antagonist (LTRA), montelukast, for 15 months. She presented fever up to 38°C with microscopic hematuria and proteinuria, serum creatinine level of 0.7 mg/dl, and C-reactive protein of 11 mg/dl. After referral to our hospital, eosinophilia and high myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) level were observed together with hematuria and proteinuria; renal biopsy examination was performed to clarify the disorder. Renal biopsy specimens showed necrotizing crescent formation, severe granulomatous angiitis in an interlobular artery, and interstitial eosinophilic infiltration. It was noted that nearly intact glomeruli were infiltrated with eosinophils. After treatment with oral prednisolone at initial dose of 40 mg (1 mg/kg body weight), urinary findings rapidly became normal with mild elevation of serum creatinine to 1.5 mg/dl and trace level of serum C-reactive protein in 1 month. Because she was previously treated with montelukast without oral corticosteroid, linkage between CSS and LTRA was highly suspected.