Endocrine Abstracts

Introduction: Paragangliomas (PGL) are rare tumours of neuroendocrine origin. Those localized in urinary bladder account for 10% of all PGL. They arises from chromaffin tissue of the sympathetic nervous system that is embedded in the muscle layer of the bladder wall. Approximately 10% of urinary bladder paragangliomas are malignant.

Case presentation: A 76-year-old female presented with a history of haematuria, hypertension, headaches and excessive sweating. A urine cytology revealed atypical cells of unknown origin. In MRI on T1- weighted imaging 5 cm lesion of urinary bladder was found. The patient was qualified to transurethral resection of bladder tumour. Due to high risk of damaging bladder wall, only endoscopic biopsy of the tumour was performed. The biopsy was consistent with a paraganglioma (positive staining for neuroendocrine neoplasm (NEN) markers without staining for keratins, Ki67 – 15–20%.) The patient was reffered to Endocrinology Department for further investigation. A 24-hour urine collection of metoxycatecholamines showed significantly elevated level of normetanephrine and 3-metoxythyramine, with metanephrine level within normal range. Alpha-blocker treatment was inititated. Computed tomography of abdomen and pelvis identified, apart from contrast-enhancing large masses of the inferior wall of the urinary bladder, suspicious, contrast-enhancing paraaortic lymph nodes and lymph nodes along right iliac vessels. 131I-MIBG SPECT/CT revealed no tracer uptake. However, 68Ga-DOTATATE PET/CT identified pathological somatostatin receptor expression lesions in urinary bladder and thoracic, abdominal and pelvic lymph nodes. Based on those results, the diagnosis of malignant, disseminated paraganglioma, was made. The patient, who refused any kind of surgery, was reffered to Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-DOTATATE.

Conclusion: Urinary bladder paraganglioma should be suspected in patitents complaining about hematuria, with accompanying hypertension and headaches. Unrevealed hormonal activity of paragangliomas, without alpha-blockage, can retard proper surgery because of severe hypertension and jeopardize patient’s safety due to possible catecholamin crisis. The diagnosis of PGL requires biochemical assessment to determine the catecholamine production. Histopathologically, the lack of keratin expression in a presumed NEN should raise the suspicion of PGL. Histopathological distinction between PGL and NEN is very important because of the ability to express somatostatin receptor 2 (SSR 2) presented by paragangliomas, which can lead to misdiagnosis - when it is based on somatostatin receptor scintigraphy. Contrarily, this ability can be very useful in diagnosis and treatment of metastatic paraganglioma by the use of 68Ga-DOTATATE PET/CT and PRRT.