BCL-2 EXPRESSION IN NORMAL ADRENAL-GLANDS AND IN ADRENAL NEOPLASMS

Archival paraffin-embedded tissue from 5 normal adrenal glands (includ ing 1 from a fetus of 28 weeks' gestation), 6 cases of adrenal cortica l hyperplasia, 9 cortical adenomas, 14 cortical carcinomas, and 11 phe ochromocytomas were immunostained with monoclonal antibody against bcl -2. Ultrastructural localization of bcl-2 protein was also performed o n selected cases. Positive immunostaining for bcl-2 was seen in all of the layers of the normal adrenal cortex, with different staining char acteristics. bcl-2 expression was never observed in the normal adrenal medulla Electron microscopic studies revealed bcl-2 to be localized p redominantly to mitochondria, with a small number of labels along the nuclear envelope. Analysis of adrenal neoplasms showed expression of b cl-2 in cortical tumors, but only one positive case in pheochromocytom as. Restriction of bcl-2 expression to adrenal cortex-derived tissue v ersus adrenal medulla-derived tissue might prove to be helpful for the differential diagnosis between cortical and medullary tumors.