[A Case of Ectopic Pheochromocytoma between the Abdominal Aorta and Inferior Vena Cava].

We report a case of ectopic pheochromocytoma which is relatively rare. A 50-year-old man was found to have an abdominal tumor on a medical examination, and contrast-enhanced computed tomography showed a retroperitoneal tumor between the abdominal aorta and the inferior vena cava. As a result of close examinations, an ectopic pheochromocytoma was suspected. He was asymptomatic and suspected infiltrating into great vessels, but possibility of a malignant neoplasm could not be ruled out for the tumor had a tendency to enlarge, the resection of the tumor was performed. During the operation, the invasion of the tumor into the great vessels was denied and the tumor was completely resected. Large fluctuation of the blood pressure was not observed during the operation. Histopathological evaluations of the resected specimen revealed the ectopic pheochromocytoma. A pheochromocytoma was newly defined as a tumor with malignant potential for metastasis in all cases by the WHO classification published in 2017. He was diagnosed as moderately malignant by GAPP score, therefore the careful follow-up was considered necessary in the future.