IMMUNOHISTOCHEMICAL STAINING OF NORMAL, HYPERPLASTIC, AND NEOPLASTIC ADRENAL-CORTEX WITH A MONOCLONAL-ANTIBODY AGAINST ALPHA-INHIBIN

Aims-To investigate the immunohistochemical staining of normal, hyperp lastic, and neoplastic adrenal cortex with a monoclonal antibody again st alpha inhibin. Also, to determine whether immunostaining with this antibody is useful in differentiating between adrenal cortical neoplas ms and other tumours involving the adrenal gland that might mimic them . Methods-Normal adrenal tissue (n = 20) and specimens from cases of a drenal hyperplasia (n = 13), adrenal cortical adenoma (n = 15), adrena l cortical carcinoma (n = 4), phaeochromocytoma (n = 8), and adrenal m etastatic tumour (n = 7) were stained with a monoclonal antibody again st the alpha subunit of human inhibin. Results-Positive staining with the anti-alpha inhibin monoclonal antibody was seen in all normal adre nal glands. Immunoreactivity was largely confined to the inner cell la yers of the adrenal cortex, with no staining of the adrenal medulla. A ll hyperplastic adrenal glands and adrenal cortical adenomas and carci nomas were also immunoreactive. The other tumours studied were negativ e. Conclusions-There is consistent immunoreactivity with the anti-alph a inhibin monoclonal antibody in normal adrenal cortex and in hyperpla stic and neoplastic adrenal cortical lesions. In the normal adrenal co rtex, positive staining is mainly confined to the zona reticularis. Ot her neoplasms involving the adrenal gland are negative. Immunohistoche mical staining with anti-alpha inhibin monoclonal antibody, performed as part of a panel, may prove to be of value in the distinction betwee n adrenal cortical carcinoma and phaeochromocytoma or metastatic tumou r.