Abstract: Objective To explore the diagnostic criteria and surgical methods in treating micro-paraganagliomas(<1cm) of urinary bladder(PUB), we now report a case series study including 5 single cases. The present study was performed to generate a comparatively novel algorithm to treat micro-paraganagliomas of urinary bladder. Methods Clinical data of 5 patients with micro-PUBs who underwent surgical treatment were obtained and analyzed retrospectively. Two male patients and three female patients were included in our study with a mean age of 51 (range from 41 to 65 years). 4 patients were reported symptomatic due to hypercatecholaminemia, while the other was free of symptoms. 24-hour urine catecholamine (CA) examination was utilized to qualitatively diagnose PUB, positive in 75% patients. Ultrasonography(USG), CT, MRI, 111In-DTPA-Octreotide scintigraphy (OctreoScan) and 1311-MIBG scintigraphy were used to locate the tumor, positive in 80%, 20%, 75%, 25% and 33% patients respectively. What’s more, all 5 patients underwent transurethral resection of tumor. Overfilling of bladder and puncture following ultrasonography guidance were performed to locate the tumors, when tumors were absent in surgical vision. Results All tumors were located and resected completely with no open conversions. It took 0.5 to 26 minutes to locate the tumor and another 3 to 10 minutes to resect the tumors. All lesions were diagnosed by histopathological confirmation, especially by immunohistochemical staining. Blood pressure return to normal level after the procedures. No local recurrence or distal metastasis were observed by performing 24-hour urine CA test, USG, cystoscopy and MRI within adequate follow-up. The mean follow-up duration was 38.6 months, ranging from 6 to 120 months．Conclusions USG and MRI examination were considered better in detecting micro PUB than CT-scan. Overfilling of bladder and puncture following USG guidance can accomplish more accurate tumor location intraoperatively if the tumors were not observed in transurethral resection procedures.

Key words: Paraganglioma, bladder neoplasm, Transurethral resection