A paraganglioma is a non-epithelial tumor which arises in the paraganglial location. Less than 10% paraganglioma are in the urinary bladder, and the young people are more easily to develop PUB. PUB arise more frequently in the trigone of bladder with an average size of 3.9cm [5]. To the best of our knowledge, we have reported the largest number of PUB patients in one center until now.
The detection and diagnosis of PUB depends on the clinical manifestation of hypertension and radiology examination in the early stage. Some patients’ symptoms may present with headache, paranesthesia, dyspnea, angina, hematuria, and lower urinary tract symptoms [6]. While PUB is always misdiagnosed as bladder cancer unfortunately, especially non -functional tumors with no symptoms. According to our previous literature review, 61.6% PUB patients were misdiagnosed before pathologic diagnosis, and less than 30% were diagnosed before the surgery [7].
Based on the difficulties of the diagnosis of PUB patients, crucial laboratory examinations and image analysis are necessary before the operation. Catecholamine (CA) which is secreted by chromaffin cells including dopamine, adrenaline and norepinephrine are important indexes. The level of these indexes, either in blood or 24-hour urinary sample, are increased in functional PUB, and theses laboratory results can help us to finish the etiology diagnosis before the operation. In our study, all the 3 non-functional PUB patients had a normal level of 24-hour urine catecholamine, NMN and MN. Almost all abnormal laboratory indexes are NE and NMN increased in functional PUB tumors. This may suggest that increased NE and NMN are specific to PUB tumors.
Image analysis provides localization diagnosis and improves etiology diagnosis. Contrast-enhanced CT and magnetic resonance imaging (MRI) are two basic screening methods. PUB performs a regular shape bladder tumor with obvious enhancement and hyperintense on T2 weighted images (T2WI) [8]. MIBG has a high specificity and sensitivity for detecting paraganglioma, and a previous study found that fluorodeoxyglucose (FDG)-PET has a higher sensitivity than MIBG [9]. Ga-68 DOTATATE PET/CT is reported to find the metastatic paraganglioma of the urinary bladder [10]. However, non-functional PUB is difficult to be detected before the operation because of lack for secreting CA and nontypical symptoms can be found. A case of functional PUB was reported even without radiographic and laboratory feature [11]. Musa Male et al. [12] recommended cystoscopy before the surgery because PUB had a cystoscopic feature of hypervascularization. However, the eventual diagnosis must be based on the histopathology and immunohistopathology after the tumor resection.
Surgery is the most important therapy for PUB. Until now, two main surgical options including transurethral resection and transurethral laparoscopic combined partial cystectomy were applied. Most of the PUB tumors are functional which can be detected in the early stage, and the tumor size was small, transurethral is a safe and better operation approach, about 1/5 patients were treated with TURBT alone [13]. Transurethral laparoscopic combined partial cystectomy is regarded to be used for the tumors who invade the muscle layer of the bladder or even deeper. Transurethral methods can help the surgeons to avoid the injury of the important anatomical structure, such as bilateral ureteral orifice. We can early coagulate the vessel at the tumor base and using short burst to limit the blood pressure fluctuations during the procedure may be beneficial [14]. At present, laser resection and electro-excision are reported to treat PUB which have a good effect [15]. While some suggestions believe that resection rarely leads to a high level of recurrence [16].
In this article, we compare the effects of both partial cystectomy and TURBT on postoperative length of stay and postoperative recurrence. The results showed that the different surgical approaches did not have an effect on postoperative recurrence and that the TURBT procedure significantly reduced the postoperative hospital stay. Moreover, recent findings suggest that TURBT is feasible for tumors less than 3cm in diameter with adequate preoperative preparation [17]. Therefore, we recommend TURBT for PUB smaller than 3 cm, while for larger tumors, partial cystectomy or radical cystectomy can be chosen depending on their invasion of the bladder wall. Pelvic lymph node dissection or biopsy is necessary if metastasis is suspected. However, due to sample size limitations, we were not able to compare the differences between the two surgical approaches separately when the tumor was less than 3 cm. Therefore, more studies are needed to confirm this conclusion. On the other hand, almost all the paraganglioma have a whole regular membrane, and excision extension involves muscularis of the bladder is the key point to respect the tumor completely, and complete excision of the membrane is the most important to avoid or decrease the rate of recurrence.
Pathology is the gold standard to definite diagnosis. Typical paraganglioma performs neuroendocrine markers combined with neuroendocrine markers and negative mesenchymal and epithelial markers. CD56, NSE, CgA, Syn vimentin, SDHB, (Von Hippel-Lindau) VHL, PGP9.5 and S-100 protein are in common use [18]. Typical PUB presents with Melan-A, α-inhibin and AE1/AE3 negative, and CgA, S-100, and SDHB positive in our study. Ki-67 > 5% means a high risk of metastasis. Genetic disorder is another occurrence factor, and SDHB is the most common gene which is associated with the highest rate of metastasis [19].