ERYTHROPOIETIN IMMUNOLOCALIZATION IN RENAL-CELL CARCINOMA

Erythropoietin (EPO) is a well-recognized hormone that induces erythro cytosis in a wide range of physio-logic and pathologic situations in m ammals. One of these situations is a paraneoplastic erythrocytosis, wh ich might be seen in association with various neoplasms, including ren al cell carcinoma (RCC), hepatoma, and cerebellar hemangioblastoma Alt hough there have been multiple studies confirming the association betw een this erythrocytosis and the production of EPO by tumor cells, immu nohistochemical detection of EPO in formalin-fixed, paraffin-embedded tissue was not described, We report on the use of microwave antigen re trieval to detect EPO in RCCs in such routinely processed tissues, We selected 19 RCCs received as nephrectomy specimens, fixed in formalin, and routinely processed, These cases were previously diagnosed on the basis of morphologic, immunohistochemical, and clinical features. We examined the immunoreactivity of these specimens with a monoclonal ant i-EPO antibody, Fetal (20 wk gestational age) liver served as a positi ve control, Intense positive immunoreactivity was observed as cytoplas mic, granular staining in fetal hepatocytes, Fourteen RCCs (10 clear c ell and 4 tubulopapillary types) demonstrated unequivocal cytoplasmic immunoreactivity,Additionally, two clear cell tumors were only focally positive, whereas three (16%) were negative, EPO immunoreactivity mig ht thus prove to be of value in the diagnosis or confirmation of RCC, particularly in the context of routinely processed material.