Paraganglioma of the urinary bladder: a challenging diagnosis in transurethral resection specimens: a case report.

Background: Urinary bladder paraganglioma is a rare neoplasm that originates from embryonic rests of chromaffin cells in the sympathetic plexus of the detrusor muscle, and which occasionally can be observed in transurethral resection specimens. Artifactual changes due to the procedure may frequently simulate an advanced urothelial carcinoma.

Case: A 65-year-old woman presented with episodic macroscopic hematuria. No symptoms of hyperadrenergic stimulation were referred. Cystoscopic examination revealed a protruding mass on the left side of the bladder. Transurethral resection (TUR) was performed, and histological examination revealed a tissue organized in solid nests delineated by delicate fibrovascular septa. There were artifactual changes that consisted of cautery effect and absence of orientation of the fragments. The tumor infiltrated the muscle layer and part of the muscularis mucosae of the bladder. No necrosis or mitoses were observed. On immunohistochemical staining, the tumor cells were negative for epithelial membrane antigen, cytokeratin 7, and carcinoembryonic antigen and positive for chromogranin A, NSE, and PGP9.5. Immunohistochemistry for S-100 highlighted sustentacular cells.

Conclusion: It is essential to consider the diagnosis of urinary bladder paraganglioma on TUR specimens in order to avoid inappropriate treatment.