Catecholamine-Secreting Retroperitoneal Paraganglioma: A Case Report and Literature Review

Paragangliomas are rare neuroendocrine tumors arising from autonomic paraganglia. These tumors have metastatic potential, and histopathological findings alone cannot reliably predict their biological behavior. Clinical manifestations range from the classic triad of headache, diaphoresis, and palpitations to incidental findings in asymptomatic patients.

A 75-year-old man was incidentally found to have a 5 cm retroperitoneal mass adjacent to the right renal hilum. Biochemical testing confirmed marked catecholamine hypersecretion, and 18F-FDOPA PET/CT demonstrated isolated uptake within the lesion without additional disease. Preoperative preparation included progressive alpha-adrenergic blockade with doxazosin for approximately 1 month, followed by atenolol for heart rate control. An open approach through a right subcostal hemichevron incision was selected because the tumor was located between the right renal artery and vein and lateral to the inferior vena cava. During dissection, an iatrogenic renal artery injury with intraoperative hemorrhage occurred, necessitating en bloc removal of the tumor, right kidney, and right adrenal gland. Histopathological examination confirmed a paraganglioma with a Ki-67 proliferation index below 1%, focal nuclear atypia, no mitotic figures, no tumor necrosis, no vascular invasion, and microscopic margin involvement. Immunohistochemistry was positive for Chromogranin A, synaptophysin, GATA-3, and S100. Germline testing using a 14-gene pheochromocytoma-paraganglioma panel identified no reported pathogenic or likely pathogenic variants. At 6 months, contrast-enhanced thoracoabdominopelvic computed tomography showed no evidence of local recurrence or metastatic disease, and plasma and urinary metanephrines had normalized, consistent with postoperative biochemical remission. The patient remains under joint endocrinology and urology follow-up with lifelong annual clinical and biochemical surveillance.

This case highlights the diagnostic and surgical challenges of a functioning perihilar retroperitoneal paraganglioma. Careful endocrine preparation, vascular planning, multidisciplinary management, and lifelong surveillance are essential, particularly when the surgical margin is microscopically involved.