A COMPARATIVE IMMUNOHISTOCHEMICAL STUDY OF PHEOCHROMOCYTOMAS AND PARAGANGLIOMAS

There is no definite morphological distinction between phaeochromocyto mas and paragangliomas. We, therefore, attempted to determine the univ ersality and differential utility of a panel of tumour markers for dia gnosis in formalin-fixed, paraffin-embedded specimens. Antibodies to n euron-specific enolase (NSE), chromogranin, synaptophysin, Leu-7, neur ofilaments, cytokeratins, carcinoembryonic antigen (CEA), melanoma ant igen HMB-45, S-100 protein and glial fibrillary acid protein (GFAP), w ere used on 11 phaeochromocytomas and 8 paragangliomas. NSE reactivity was detected in 10 phaeochromocytomas and in all paragangliomas. Chro mogranin reactivity was found in all but two cases (one phaeochromocyt oma and one paraganglioma). Synaptophysin reactivity was present in 10 phaeochromocytomas and in the 8 paragangliomas. Ten phaeochromocytoma s stained for Leu-7, but none of the paragangliomas did. S-100-positiv e cells (sustentacular or type II cells) were found in 8 phaeochromocy tomas and 7 paragangliomas. GFAP stained sustentacular cells of only o ne paraganglioma. Only in 5 phaeochromocytomas was there a focal react ion by neurofilaments. Cytokeratins, CEA and HMB-45 were never detecte d. 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 t o 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 immunostainin g in any case.