Endocrine Abstracts

JOINT3537

Introduction: Paragangliomas (PGL) are rare neuroendocrine tumors located along the sympathetic or parasympathetic ganglia (1). While these tumors are commonly associated with excessive production of catecholamines, some can be biochemically silent. Biochemically negative PGL (BNPGL) are defined by normal levels of plasma and urinary metanephrines and normetanephrines, as well as plasma methoxytyramine(2). This case report presents a 59-year-old woman who was diagnosed with a biochemically negative retroperitoneal PGL.

Case presentation: She had a 14-year history of hypertension and presented with chronic right lumbar pain evolving for the past 2 years. She had no other clinical signs. Laboratory tests revealed prediabetes with an HbA1c level of 6.3%. The patient’s plasma and urinary metanephrine, normetanephrine and 3-methoxytyramin levels were within normal ranges. Imaging studies revealed a 28 mm tumor with a spontaneous density of 34 Hounsfield units (HU) on abdominal CT, which exhibited intense and heterogeneous enhancement. The tumor was located near the diaphragm’s pillar and the right border of the inferior vena cava. Further evaluation with MRI showed heterogeneous tumor with hyperintense T2 signal. An octreoscan demonstrated localized hyperfixation, with no additional areas of fixation noted. The tumor was successfully removed through a laparotomy. The histopathological examination of the surgical specimen confirmed the diagnosis of a paraganglioma with a PASS score of 1.

Discussion: Biochemically silent PGL are often difficult to diagnose due to their lack of characteristic biochemical markers, which makes them challenging to distinguish from other retroperitoneal masses. These tumors are more frequently found in the head and neck region, and are often associated with mutations in the SDHx genes (3). Imaging studies play a crucial role in the diagnosis of silent PGLs. Their discovery often occurs incidentally, as in this case, when imaging is conducted for unrelated clinical concerns. The management of BNPGL typically involves surgical resection with careful preoperative management with alpha- and beta-blockers in order to mitigate the risk of perioperative complications

Conclusion: Biochemically silent PGL, although rare, should be considered in the differential diagnosis of retroperitoneal masses, especially when imaging findings are suggestive of a paraganglionic origin.

Citations: 1. Lenders JWM, Pheochromocytoma and Paraganglioma: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 1 juin 2014;99(6):1915–42. 2. Constantinescu G, Silent pheochromocytoma and paraganglioma: Systematic review and proposed definitions for standardized terminology. Front Endocrinol. 17 oct 2022;13:1021420.3. Eisenhofer G, Catecholamine metabolomic and secretory phenotypes in phaeochromocytoma. Endocr Relat Cancer. 21 déc 2010;18(1):97–111.