IODINE-131-METAIODOBENZYLGUANIDINE UPTAKE IN METASTATIC CARCINOID-TUMOR TO THE ORBIT

Metastatic tumor is one of several etiologies of space-occupying masse s in the orbit that accounts for 1%-13% of all orbital masses (I). In the adult patient population, breast cancer is the most common tumor t o metastasize to the orbit followed by metastases from the lung, prost ate and gastrointestinal tract (2). It is rare for carcinoid tumors to metastasize to the eye or to the orbit. Carcinoid tumors arise from K ulchitsky cells that originate in the neural crest. Histologically, th ese tumors resemble, but are not as aggressive as, adenocarcinomas. Mo st carcinoids arise in the gastrointestinal tract or the lung. The mos t common site for carcinoid metastases is the liver. On anatomical ima ging studies, such as CT and magnetic resonance imaging, metastatic or bital carcinoid tumors appear as nonspecific tumor masses. Carcinoid t umors have an affinity for uptake of the radiopharmaceutical (131)l-me taiodobenzylguanidine (MIBG) (3). We report a case of a patient with a known carcinoid tumor who developed a left orbital mass that demonstr ated abnormal uptake of (131)l-MIBG indicative of metastatic carcinoid tumor to the orbit.