Eosinophilic cystitis: successful long-term treatment with montelukast sodium.

We report a rare case of eosinophilic cystitis in a 6-year-old boy who presented with irritative voiding symptoms, peripheral eosinophilia, and a bladder mass initially visualized on ultrasonography. Cystoscopy and transurethral biopsy confirmed the diagnosis. Complete resolution of his symptoms occurred within 1 week of corticosteroid use and the x-ray findings improved within 6 weeks. At 6 months of follow-up, the patient continued to require a leukotriene receptor antagonist (montelukast sodium) despite several attempts to discontinue its use. We propose that eosinophilic cystitis in children who present with peripheral eosinophilia will often require long-term treatment.