Background: Paragangliomas occur most commonly in head and neck region and much less frequently, they are found in the retroperitoneum. Composite paraganglioma-ganglioneuroma of the retroperitoneum is very rare.
Case presentation: We present an unusual case of retroperitoneal composite paraganglioma-ganglioneuroma discovered on computed tomography in a 63-year-old female patient. Routine hematological examination and biochemical tests were within normal limits. Plasma adrenaline was 0.042 ng/ml, plasma noradrenaline 0.341 ng/ml, and plasma dopamine <0.01 ng/ml. An abdominal contrast-enhanced CT scan and magnetic resonance imaging revealed a 6.5 cm heterogeneous retroperitoneal mass with a cystic component. The retroperitoneal tumor accumulated (131)I-Metaiodobenzylguanidine ((131)I-MIBG) 48 hours after radioisotope injection. Under the diagnosis of paraganglioma in the retroperitoneum, the patient underwent surgery. The resected tumor (6.5 x 5 x 3 cm) was solid and easily removed en bloc. The cut surface of the tumor and histology revealed two different components in the tumor: paraganglioma centrally and ganglioneuroma on the periphery. She remains disease-free 18 months after surgery.
Conclusion: This case reminds us that neuroendocrine tumor should be included in the differential diagnosis of a retroperitoneal mass although composite paraganglioma-ganglioneuroma in the retroperitoneum is very rare.