Transarterial Embolization and Doxorubicin Eluting Beads-Transarterial Chemoembolization (DEB-TACE) of Malignant Extra-Adrenal Pheochromocytoma

Abstract

Extra-adrenal pheochromocytomas (EAPs) are neuroendocrine tumors that arise from paraganglion cells of the sympathetic component of the autonomic nervous system. The paraganglia are chromaffin tissue complexes that extend along the paravertebral axis [1]. As part of the autonomic nervous system, these paraganglia are the dominant source of catecholamine production during early childhood [2]. Failure of involution of these paraganglia leads to the development of extra-adrenal pheochromocytomas. The majority of intra-abdominal paragangliomas present at the organ of Zuckerkandl (to the left of the aorta near the inferior mesenteric artery takeoff). Tumors below the diaphragm are typically functional with symptoms relating to excess catecholamine secretion. Generally, patients report nonspecific symptoms, such as headaches, sweating, palpitation, anxiety, and tremors. Biochemical workup demonstrates elevated levels of plasma and urinary catecholamines and their metabolites. Provided there is no contraindication, a contrastenhanced CT should be the initial imaging modality because it is readily available and highly sensitive. Scintigraphy with I-labelled metaiodobenzylguanidine (I-MIBG) is the most common functional study used. The treatment traditionally consists of open or laparoscopic exploration and resection with preoperative a and b blockade [3]. It is now known that EAPs demonstrate potential malignant change in up to 50% of patients, far greater than the 10% reported for pheochromocytomas [4]. Because there are no pathognomonic histological findings that distinguish benignity from malignancy, the diagnosis of malignant transformation is made on the basis of the development of recurrence or metastases and presence of lymph nodes.