Malignant pheochromocytoma: predictive factors of malignancy and clinical course in 16 patients at a single tertiary medical center

Abstract

Metastases appear in approximately 10% of patients with pheochromocytoma. There is no predictive marker of malignancy. The aim is to describe clinical course of patients with malignant pheochromocytoma and to identify predictive features of malignancy. The method involves retrospective analysis of patients files diagnosed with malignant pheochromocytoma at our institution between January 1, 1980 and December 31, 2008. We identified 16 patients with malignant pheochromocytoma. There were more men than women (10/6). Mean age of patients at time of diagnosis was 37.75-year-old. Time of occurence of metastases ranged from 0 to 22 years after first diagnosis of pheochromocytoma. The mean size of the primary tumor was 12.1 cm. High levels of chromogranin A at the time of diagnosis were associated with the presence of metastases. The pheochromocytoma of the adrenal gland scoring scale (PASS) histological evaluation in adrenal primary tumors was above four in all cases but one. All patients had initial surgery, followed in most cases by palliative therapy: chemotherapy (streptozocin, cyclophosphamide-vincristine-dacarbazine, thalidomide, imatinib, everolimus) or ¹³¹I-MIBG; only the latter had replicable encouraging response evaluation criteria in solid tumor response rates. We observed a 10-year survival rate of 50% after initial diagnosis of pheochromocytoma, and 25% after diagnosis of metastasis. Metastasis can occur very late after the initial diagnosis of pheochromocytoma. High chromogranin A levels may be associated with the presence of metastases and poor prognosis. Histological adrenal PASS higher than 4 appears to be suggestive of malignancy. The best therapeutic approach remains to be established.