Extra-adrenal pheochromocytoma in the organ of Zuckerkandl: diagnosis and treatment strategies.

Pheochromocytoma (PHEO) and paraganglioma (PGL) are rare catecholamine-secreting neuroendocrine tumors arising from chromaffin tissue and can occur within the adrenal medulla (PHEO) or extra-adrenal sites (PGL). The most common site for PGL is the organ of Zuckerkandl, extra-adrenal chromaffin tissue near the origin of the inferior mesenteric artery.We here present 2 patients with extra-adrenal PGL in the organ of Zuckerkandl, located by iodine-123-metaiodobenzylguanadine ( (123)I-MIBG) scintigraphy and thereafter treated surgically or with iodine-131-metaiodobenzylguanadine ( (131)I-MIBG). First, in a 15-year-old boy with clinical suspicion of PHEO, the diagnosis was established by biochemical evaluation and confirmed by further imaging studies, including CT and (123)I-MIBG, as PGL in the Zuckerkandl organ. The tumor was completely resected by laparotomy. Second, in a 70-year-old woman presenting with progressive hypertension and palpitations, MR and (123)I-MIBG revealed a singular tumor lesion with abnormal (123)I-MIBG uptake in the Zuckerkandl organ. Due to severe general vascular disease, surgery was not performed and instead the patient underwent (131)I-MIBG therapy. The patient showed a good symptomatic response with improvement of symptoms and no relevant side-effects of therapy.