[Inverted papilloma of the urinary bladder: three case reports].

We report three cases of inverted papilloma of the urinary bladder. Case 1. A 19-year-old male complained of pollakisuria, gross hematuria and micturition pain. Cystoscopy revealed a smooth-surfaced tumor on a stalk at the bladder neck. The tumor was removed transurethrally. Histological diagnosis was inverted papilloma. As a safe guard, intravesical chemotherapy (Adriamycin) was performed, since pathological findings revealed a small region with mild atypical cells in the removed tumor. The patients has been subsequently followed up for ten years without any evidence of recurrence. Case 2. A 63-year-old male was admitted to our hospital because of a bladder tumor incidentally found by abdominal ultrasonography. The tumor was removed transurethrally. Histological diagnosis was inverted papilloma. The patient has been subsequently followed up for one year without any evidence of recurrence. Case 3. A 71-year-old male complained of pollakisuria, loss of urinary force and interruption of the urinary stream. A smooth-surfaced tumor found at the bladder neck was removed transurethrally. Histological diagnosis was inverted papilloma. Three months later, cystoscopy revealed two sessile papillary tumors on the left lateral wall of the urinary bladder. Pathological diagnosis was transitional cell carcinoma (G2, pTa). Although the inverted papilloma is a benign tumor, there is a possibility of recurrence or development of transitional cell carcinoma. Therefore, we advocate periodical follow-up examinations.