Giant botryoid fibroepithelial polyp of bladder with myofibroblastic stroma and cystitis cystica et glandularis.

A 3-year-old boy presented with a single episode of gross hematuria and no history of previous urinary tract disorder. Imaging studies revealed a large complex polypoid filling defect in the bladder lumen. Several attempts at transurethral biopsy and cytological examination of the urine revealed clumps of benign epithelial cells, but suspicion of a malignant neoplasm such as rhabdomyosarcoma remained high and the lesion was resected. The specimen measured 15 cm, had a narrow zone of attachment to the bladder mucosa, and was grossly botryoid. Changes typical of cystitis cystica et glandularis were present at and near all surfaces. Myxoid stroma contained scattered benign fibroblasts, myofibroblasts, and smooth muscle cells. Inexplicably, one of two karyotyped stromal cells demonstrated a translocation usually associated with rhabdomyosarcoma. This child is well without evidence of bladder abnormality 1.5 years after surgery.