P504S/α-methylacryl CoA racemase has been shown to be a relatively sensitive and specific positive marker for prostatic adenocarcinoma. The potential utility of P504S in renal cell neoplasms has not been explored in a large series. We assessed the diagnostic value of P504S in 332 cases of nonprostatic neoplasms using the avidin-biotinperoxidase complex technique, including 115 renal neoplasms, 28 metastatic renal cell carcinomas (RCCs), and 189 nonrenal neoplasms. The results demonstrated that a granular, cytoplasmic staining pattern for P504S was observed in 48 of 70 (68.6%) conventional (clear cell) RCCs, 15 of 15 (100%) papillary RCCs, 2 of 7 (29%) chromophobe RCCs, and 2 of 8 (25%) oncocytomas. Among the 70 cases of clear cell RCC, positivity of P504S was seen in 40%, 71%, 94%, and 75% of RCCs with Furhman nuclear grade I, II, III, and IV, respectively. Strong immunostaining was present in each case (86/86) in the proximal tubules adjacent to the renal neoplasm. Eighty-two percent of metastatic RCCs (23/28) were positive for P504S. However, only 24 of 189 (13%) nonrenal malignancies were positive. The 24 positive cases included 12 of 13 (92%) colorectal adenocarcinomas, 6 of 30 (20%) ductal carcinomas of the breast, and 4 of 23 (17%) adenocarcinomas of the lung. These findings suggest that P504S is a useful marker in diagnosing primary and metastatic RCCs, although it has little value in differentiating chromophobe RCC from oncocytoma.
From the *Department of Laboratory Medicine, Geisinger Medical Center, Danville, Pennsylvania, U.S.A.; the †Department of Pathology, Temple University Hospital, Philadelphia, Pennsylvania, U.S.A.; and the ‡Department of Pathology, Northwestern Memorial Hospital, Chicago, Illinois, U.S.A.
Received for publication April 2, 2003; accepted September 18, 2003.
Reprints: Fan Lin, MD, PhD, Department of Laboratory Medicine, MC 01-31 Geisinger Medical Center, 100 N. Academy Ave., Danville, PA 17822, U.S.A. (e-mail: Flin1@geisinger.edu).