[New histopathologic data of prognostic value in extra-adrenal paragangliomas. Study of 9 cases]

The biological behavior of paragangliomas is difficult to evaluate by classic histological criteria thus justifying the use of immunohistochemical markers as prognostic factors.

Nine extra-adrenal paragangliomas (three jugulo-tympanic, four carotid-body tumors, and two retroperitoneal) were studied by conventional histological criteria, and also by chromogranin A and neuron-specific enolase (NSE) immunohistochemical staining for the study of chief cells, and S-100 as a marker of sustentacular cells. The rate of cell proliferation was studied by the proliferating cell nuclear antigen (PCNA). The correlation between these parameters and the clinical evolution of the neoplasms, which were classified as benign, locally aggressive, and malignant (with metastasis), were also analyzed.

The atypia and the mitotic rate did not correlate with the behavior of the tumor. Less immunostaining with the anti-S-100 and anti-chromogranin A antibodies was observed in the malignant paragangliomas and in those which were locally aggressive. In the benign tumors the proliferative rate (PCNA) oscillated between 0.7% and 3.7%, and 40 or less PCNA positive cells were counted in 10 high-power field (HPF) (40x). In malignant and locally aggressive tumors the proliferative rate was 5% or more, with 60 or more cells that were positive for PCNA being found in 10 HPF.

The histopathologic signs implying worse prognosis in extra-adrenal paragangliomas are a decrease in chromogranin A and S-100 immunoreactivity and a rate of cell proliferation of 5% or greater, or a number of cells stained for proliferating cell nuclear antigen greater than 50 in 10 high-power field.