INHIBIN A EXPRESSION IN ADRENAL NEOPLASMS - A NEW IMMUNOHISTOCHEMICALMARKER FOR ADRENOCORTICAL TUMORS

The lack of specific immunohistochemical markers for adrenocortical tu mors often causes problems in pathologic diagnosis of adrenal neoplasm s. Inhibin is a glycoprotein that is normally expressed in gonadal sex cord stromal elements and tumors and in normal adrenocortical cells, The immunohistochemical expression of inhibin A was studied in a serie s of 58 adrenal tumors, which included pheochromocytomas, adrenocortic al adenomas and carcinomas, and metastatic carcinomas. Twelve renal ce ll carcinomas were also evaluated. Normal adrenal cortex showed a mode rately uniform staining pattern: weak staining in the glomerular layer , moderate in the fascicular layer, and a strong and diffuse reactivit y in the reticular zone. All 20 adrenocortical adenomas were strongly and diffusely positive, although those associated with hyperaldosteron ism exhibited a patchy staining distribution. Seven of 8 adrenocortica l carcino mas were strongly and diffusely positive, whereas 10 of 11 p heochromocytomas were negative. Conversely, inhibin was not detected i n any adrenal metastases and renal cell carcinomas. The results sugges t that inhibin A may be a good market for adrenocortical tumors and ma y be of great interest in the differential diagnosis with pheochromocy tomas, metastatic tumors, and renal cell carcinomas that spread into t he retroperitoneum.