The use of immunohistochemical expression of SF-1 and EMA in distinguishing adrenocortical tumors from renal neoplasms.

Steroidogenic factor -1 (SF-1) is an orphan member of the nuclear hormone receptor superfamily, and is considered to play an important role in the differentiation of steroidogenic tissues. In this study, we compared the immunohistochemical stains of SF-1 and epithelial membrane antigen (EMA) in non-neoplastic adrenal tissue, and adrenal and renal tumors using tissue microarrays (TMAs). The adrenal tissue array included 19 cases of normal adrenal cortex, 22 cases of adrenal adenoma, and 20 cases of adrenal cortical carcinoma. The renal tissue array included 20 cases of each of the following types of renal cell carcinoma: clear cell, papillary, and chromophobe. In addition, 20 cases of renal oncocytoma were also included in the study. SF-1 showed positive staining in all cases (100%) of normal adrenal cortex and adrenal cortical adenoma, and in 18 (90%) cases of adrenocortical carcinoma. In renal tumors, SF-1 showed negative stains in all of oncocytoma, papillary, and chromophobe renal cell carcinoma. Only 3 out of 20 cases of clear cell renal cell carcinoma showed weak positivity in approximately 10% of tumor cells. EMA stained positively in 85%, 95%, 100%, and 95% of clear cell, papillary, chromophobe renal cell carcinomas, and oncocytomas, respectively. EMA was completely negative in the adrenal TMAs. In conclusion, SF-1 and EMA may be helpful in the differentiation of adrenal tumors from renal tumors in difficult cases.