[Bladder tumors: false recurrences].

The use of the new cytostatics for prophylactic therapy of superficial bladder tumor recurrence has been associated with fibrino-necrotic ulcers and eosinophilic cystitis. We underscore the problems in making the differential diagnosis which sometimes present with true tumor necrosis. We describe the characteristic features of both pathological conditions which permit these to be recognized before endoscopic maneuvers are performed. Their presenting features and course are analyzed.