Objective: Napsin-A is an aspartic protease present lung, renal, and thyroid cells. There are few studies evaluating Napsin-A in renal neoplasms. Therefore, we studied IHC expression of Napsin-A in a wide spectrum of renal tumors. Method: IHC for Napsin-A (rabbit polyclonal antibody) was performed in a series of 334 cases of primary and metastatic renal tumors on TMA. Cytoplasmic immunoreactivity was scored: intensity (0-3+) and extent (% of tumor cells: 0-3). The 2 scores were added: positive case: combined IHC score>2; negative if combined score of 2 or less. Objective: The diagnosis of prostatic carcinoma can be challenging on needle core biopsies. The aim of this study was to assess the utility of alpha-methylacyl-CoA racemase (AMACR/P63) antibody cocktail for prostate cancer diagnosis. A prospective analysis of 50 consecutive radical prostatectomy specimens and 50 prostate needle biopsy semples was performed to select histological sections showing foci of minimal prostatic carcinoma, high grade prostatic intraepithelial neoplasia (HGPIN) and benign mimickers of prostatic carcinoma (atrophy, adenosis). Method: Serial histological sections were stained with hematoxylin and eosin, Van Gieson and immunomarkers: AMACR and P63 using a prediluted antibody cocktail. Results: The cocktail was very useful in highlighting prostatic carcinoma associated with HGPIN (flat or cribriform) and distorted foci of minimal carcinoma. AMACR was positive with moderate and strong staining in almost all cases for which the immunohistochemical result converted the atypical diagnosis to a final cancer diagnosis. The cases whose diagnosis was changed from "atypical" to cancer were all highly suspicious for cancer based on HE histology and negative basal cell markers. Conclusion: This cocktail would be of diagnosis utility when limited tissue is available for histopathological evaluation of small diagnostically difficult foci (prostate needle biopsy and surgical specimens).