PGP9.5 Expression in Kidney Tumors

Objectives: Protein gene product (PGP9.5), also known as ubiquitin carboxyl-terminal esterase L1 (UCHL1), is a neuron-specific protein structurally and immunologically distinct from neuron-specific enolase. Standard immunohistochemical techniques have demonstrated the presence of PGP9.5 in neurons and nerve fibers in the central and peripheral nervous system, neuroendocrine cells, spermatogonia, and Leydig cells of the testis, ova, cells of both pregnant and nonpregnant corpus luteum and renal tubules. Studies have also showed that this immunostain may help to differentiate collecting duct carcinoma from urothelial carcinoma involving the renal pelvis. The purpose of this study is to explore the expression of PGP9.5 in various kidney tumors as diagnosis on morphology alone can be quite daunting. Methods: A total of 44 kidney tumors (10 oncocytomas, 10 chromophobe renal cell carcinomas, 10 conventional renal cell carcinomas, 10 papillary renal cell carcinomas, and 4 metanephric adenomas) were analyzed for PGP9.5 expression with appropriate controls. All cases were reviewed for histologic confirmation.