A comparative immunohistochemical study of phaeochromocytomas and paragangliomas.

There is no definite morphological distinction between phaeochromocytomas and paragangliomas. We, therefore, attempted to determine the universality and differential utility of a panel of tumour markers for diagnosis in formalin-fixed, paraffin-embedded specimens. Antibodies to neuron-specific enolase (NSE), chromogranin, synaptophysin, Leu-7, neurofilaments, cytokeratins, carcinoembryonic antigen (CEA), melanoma antigen HMB-45, S-100 protein and glial fibrillary acid protein (GFAP), were used on 11 phaeochromocytomas and 8 paragangliomas. NSE reactivity was detected in 10 phaeochromocytomas and in all paragangliomas. Chromogranin reactivity was found in all but two cases (one phaeochromocytoma and one paraganglioma). Synaptophysin reactivity was present in 10 phaeochromocytomas and in the 8 paragangliomas. Ten phaeochromocytomas stained for Leu-7, but none of the paragangliomas did. S-100-positive cells (sustentacular or type II cells) were found in 8 phaeochromocytomas and 7 paragangliomas. GFAP stained sustentacular cells of only one paraganglioma. Only in 5 phaeochromocytomas was there a focal reaction by neurofilaments. Cytokeratins, CEA and HMB-45 were never detected. We conclude that NSE, chromogranin, synaptophysin and S-100 protein are useful markers of both types of tumour, whereas GFAP staining is limited to a small number of these neoplasms. Leu-7 reactivity seems to favour diagnosis of phaeochromocytoma rather than paraganglioma, but further studies with larger series are needed to confirm this. Unlike previous reports, we did not find cytokeratin or HMB-45 immunostaining in any case.