ABSTRACT
Purpose To study the clinicopathologic feature, classification, benign or malignant histological features and differential diagnosis of extra-adrenal paraganglioma.Methods We performed a retrospective analysis of 21 cases of extra-adrenal (sympathetic and parasympathetic) paraganglioma. Histological, immunohistochemical findings, and follow-up data were reported with review of the relative literatures.Results There were 10 male and 11 female patients aged from 9 to 81 years (mean 46.5 years).Ten tumors occurred in the retroperitoneum, seven in the neck, and one case in the mediastinum, urinary bladder, spermatic cord and kidney, respectively.There were 3 cases of functional and 18 cases of non-functional paragangliomas.Histologically, the tumor was composed of chief cells and sustentacular cells. The chief cells were arranged in nests, alveolAR~-like and stereo-like structures.They were surrounded by sustentacular cells partly or completely.There was one malignant case, in which tumor cells had significant cell atypia and nuclear mitosis, and focal or diffuse necrosis, regional lymph node metastasis and blood vessel involvement were also observed.Immunohistochemical investigations revealed chief cells were intensely positive for neuroendocrine markers such as NSE, CgA, Syn and NF, but negative for CK, EMA and SMA.Sustentacular cells were positive for S-100 protein.The malignant cells were only positive for NSE and weakly positive for CgA.Eighteen cases were followed up.One patient developed to multi-organ metastasis and died.One patient was diagnosed as benign extra-adrenal paraganglioma that recurred and involved adjacent organs after 3 years.Conclusions It is generally considered that malignant potential, local invasiveness and distant metastasis are not correlated with the histological appearances of the extra-adrenal paraganglioma.So,further follow-up will be needed. It is necessary to emphasize the differential diagnoses of extra-adrenal paraganglioma from other pleiomorphic tumors.