Polypoid cystitis is recognized frequently in patients with indwelling catheters and is seen mostly on the dome and posterior wall of the bladder which corresponds to the localization of the tip of the catheter. It may be difficult to distinguish it from transitional cell carcinoma macroscopically at cystoscopy because of exophytic nature of the lesion, especially in patients with no history of a catheter².

In this case, we present the radiologic and pathologic features of patient with polypoid cystitis who did not have an indwelling catheter and was confused with bladder tumor at initial radiologic and cystoscopic evaluation.

The abdominal ultrasound showed a 7 mm polypoid mass projecting into the bladder lumen (Figure 1). During cystoscopy, sessile, papillary lesion was seen on the trigon of bladder. Transurethral resection of the tumor was performed. The pathological diagnosis was polypoid cystitis (Figure 2).

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Figure 1: Transabdominal US image was shown a 7 mm solid homogeneous echoic mass protruding into the bladder lumen.

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Figure 2: Microscopic examination of the hematoxylin and eosin stained sections revealed broad-based papillae with submucosal edema and scattered inflammatory cells.

At cystoscopy, or on microscopic examination, polypoid cystitis may be confused with transitional cell carcinoma^6,7. On gross inspection and microscopic examination, the fronds of polypoid cystitis are typically much broader than those of a papillary carcinoma. In polypoid cystitis, the urothelium may be hyperplastic, but usually it is not as stratified as in a carcinoma; additionally, umbrella cells are more often present. The fibrovascular cores of the papillae of a transitional cell carcinoma typically lack the prominent inflammation that characterizes polypoid cystitis. Large papillae of a transitional cell carcinoma also often give rise to smaller papillae, a feature less commonly seen in polypoid cystitis⁸.

Focal masses of the bladder may be neoplastic or may develop secondary to congenital, inflammatory, idiopathic, or infectious sources. Clinical, macroscopic, and radiologic findings for these masses may overlap⁹.

All polypoid or papillary lesions in patients with or without a catheter should be harvested for microscopic examination to make a confident differential diagnosis. The clinical features and pathologic findings may reliably help the pathologist to distinguish polypoid cystitis from papillary transitional cell carcinoma.

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