Functioning metastases of a nonfunctioning paraganglioma.

A case of nonfunctioning paraganglioma, initially qualified as benign, is described. Two years following extirpation, functioning bone and lung metastases were manifested by hypertensive crises and increased levels of vanilmandelic acid and catecholamines in urine. The criteria for benign and malignant paragangliomas are discussed with regard to functional transformation of the tumor described in this case. It is concluded that the phenotypic heterogeneity of the primary tumor cells could explain the difference in biological behavior of the primary tumor and its metastases.