Functional paraganglioma of the bladder: Both radiographic-negative and laboratory-negative case.

INTRODUCTION: Paraganglioma has been determined to be an extra-adrenal pheochromocytoma. Paraganglioma of the bladder is a rare entity, accounting for 0.06% of all bladder tumors. CASE
PRESENTATION: A 58-year-old woman had been annually followed up since being diagnosed with rectal cancer 5 years ago. In January 2018, follow-up computed tomography detected a bladder tumor, and she was referred to our department for a further examination. Cystoscopy revealed a submucosal tumor on her right bladder wall. We performed transurethral resection of the bladder tumor. When we first marked the tumor margin, the systolic blood pressure increased, so we abandoned resection. We performed meta-iodobenzylguanidine scintigraphy and acid urinary collection, neither of which revealed any abnormal findings. We therefore performed open partial cystectomy based on a clinical diagnosis of paraganglioma of the bladder. The pathological findings revealed paraganglioma of the bladder.
CONCLUSION: We herein report a case of paraganglioma of the bladder.

computed tomography

meta‐iodobenzylguanidine

magnetic resonance imaging

T1‐weighted imaging

Functional paraganglioma of the bladder is seen in both radiographic‐negative and laboratory‐negative cases.

Partial cystectomy is a standard option for managing paraganglioma of the bladder.

Introduction

Paraganglioma has been determined to be an extra‐adrenal pheochromocytoma. Paraganglioma accounts for 18% of all pheochromocytoma cases. Paraganglioma of the bladder is a particularly rare entity, accounting for 0.06% of all bladder tumors. We encountered a case of intraoperative high blood pressure at the time of tumor resection. We therefore re‐tried tumor resection by surgical partial cystectomy.1

We herein report the first case of paraganglioma of the bladder with negative findings on both radiography and laboratory testing.

Case presentation

A 56‐year‐old woman underwent laparoscopic rectal tumor resection with annual follow‐up using CT. In January 2018, CT revealed a bladder tumor on her right bladder wall. Cystoscopy confirmed a bladder tumor in the submucosa (Fig. 1). MRI revealed low intensity on T1WI and high intensity on T2WI (Fig. 2). The possibility of paraganglioma was considered after cystoscopy revealed a submucosal tumor. We then checked the adrenal hormone levels preoperatively, but no abnormalities were seen. We therefore planned transurethral resection of the bladder tumor.

Figure 1

Cystoscopic findings.

Figure 2

(a) Contrast‐enhanced CT. MRI: (b) T1WI, (c) T2WI, and (d) DWI. (e) MIBG scintigraphy.

In April 2018, she underwent transurethral resection of the bladder tumor, but when we marked the resection margin, her blood pressure dramatically increased to 230 mmHg. We therefore abandoned transurethral resection. We performed MIBG scintigraphy and acid urinary collection, neither of which revealed any abnormal findings (Fig. 2e). At this point, we clinically suspected paraganglioma and administrated a doxazosin mesilate (1.0 mg/day).

In July 2018, partial cystectomy was performed after observing the bladder tumor cystoscopically. During tumor resection, we used Message Tseng Baum scissors instead of an acusector. She was discharged home 3 days postoperatively and was free from recurrence for 6 months after surgery. A hormonal examination showed almost normal findings (adrenaline 25 pg/mL, noradrenaline 122 pg/mL, dopamine <5 pg/mL, urine metanephrine 0.09 mg/day, urine normetanephrine 0.22 mg/day).

The pathological findings revealed rich endoplasmic reticulum cells growing with an alveolar form. Immunohistochemical staining showed positive findings for chromogranin A, synaptophysin, and CD56 (Fig. 3). Based on these findings, paraganglioma of the bladder was diagnosed.

Figure 3

(a) HE findings: The carcinomatous element consisted of urothelial carcinoma with squamous differentiation. Immunohistochemistry of (b) synaptophysin, (c) CD56, and (d) chromogranin A.

Discussion

Paraganglioma has been defined as an extra‐adrenal pheochromocytoma and consists of paraganglion cells, accounting for 15–22% of all pheochromocytomas.2 Paraganglioma of the bladder is a relatively rare disease, accounting for 0.06% of all bladder tumors. In the urinary system, the bladder shows most frequent in 79.2%, followed by the urethra (12.7%), renal pelvis (4.9%), and ureter (3.2%).3, 4 Although paraganglioma is most likely to be seen in the dome, trigone, and posterior wall, we examined a total of 39 reports including information on the tumor site, with no typical distribution observed (Fig. 4). A previous report showed that paraganglioma of the bladder tended to occur more frequently on the right side than on the left side; however, no mechanism for this finding has been suggested.

Figure 4

Distribution of reported paraganglioma sites in the bladder.

This case was suspected of being paraganglioma because when we started to resect this tumor, the patient's blood pressure increased to over 200 mmHg. Seventeen percent of paraganglioma cases are reported to be nonfunctional tumors. The functional groups are characterized by the presentation of various disease‐associated symptoms, elevated levels of catecholamine and metabolites in plasma and/or urine, and positive reaction on MIBG or octreotide scintigraphy; however, no apparent cut‐off point has been determined.5

Paraganglioma is defined as a benign tumor, but 15–20% of cases show a malignant phenotype and develop metastasis or recurrence. The pathological determination of whether the tumor is benign or malignant is difficult and clinical follow‐up is the only way to diagnose a paraganglioma as benign or malignant. Furthermore, malignant paraganglioma has shown resistance to systemic chemotherapy and radiation therapy.6, 7 The standard treatment of paraganglioma of the bladder is partial cystectomy because this tumor tends to extend into the muscle layer. Radical cystectomy is sometimes selected for difficult cases. Based on these previous findings, imaging examinations should be scheduled to check for metastasis or recurrence using MRI or cystoscopy.

In conclusion, we herein report a rare case of paraganglioma of the bladder with negative findings on both radiography and laboratory testing.

Conflict of interest

The authors declare no conflict of interest.

Declarations

Written informed consent to participate in this study and for the publication of this report was obtained from the patient for ethics approval.

Consent for publication

Written informed consent was obtained from the patient. A copy of the written consent form is available for review from the Editor‐in‐Chief of this journal.

Availability of data and material

Due to ethical restrictions, the raw data underlying this paper are available upon request to the corresponding author.

Table S1. Previous published reports in Japan containing information on tumor sites.

Click here for additional data file.