Extra-adrenal paragangliomas of the retroperitoneum: A clinicopathologic study of 12 tumors.

The clinical and pathologic features of 12 extra-adrenal paragangliomas of the retroperitoneum are presented. The patients (eight men, four women) had an average age of 43 years at the time of diagnosis; three had symptoms related to excess catecholamine secretion. Complete surgical resection was attempted in each case but was possible for only four patients. Five tumors were malignant; four patients died from regional and/or distant metastases 17 months to 10 years after surgery. One patient was alive with metastatic paraganglioma 25 years after initial treatment. Each patient with metastatic or locally recurrent paraganglioma had incomplete resection of the primary tumor. An important microscopic feature of each paraganglioma was the presence of cytoplasmic argyrophilia. Three of the five metastasizing paragangliomas showed readily identifiable mitoses or evidence of vascular invastion; the two other cases and all of the benign tumors lacked these features. Our findings suggest that in some cases histology may prove helpful in evaluating the malignant potential of these tumors.