Results: The %37 reduction was achieved in number of blocks. The concordance rates between two sampling methods were %40, %50.4, %70.3, and %60 respectively for Gleason scores, perineural invasion, extraprostatic extension and pathologic stages. Conclusion: Although the limited sampling protocol provides statistically significant results, because of critical role of pathological assessment in treatment of prostatic adenocarcinoma, they can be found unsatisfactory for many pathologists. Objective: Initially described in embryonic neuroepithelium, nestin is an intermediate filament involved in cell differentiation and transiently related to vimentin, keratin and glial fibrillary acidic protein (GFAP). In tumoral and vascular proliferation, nestin is recognized in stem/progenitor cells. The octamer-binding transcription factor 4 (OCT-4) is a biomarker of this lineage. Since there are few data concerning the presence of nestin in Leydig cells and testicular tumors, our aim was to investigate a series of Leydig cell hyperplasia and tumors. Method: 31 cases (13 hyperplasia, 14 adenomas, 2 malignant Leydig cell tumors and 2 lymph node metastases) and controls were immunostained with anti-nestin, vimentin, keratin, GFAP and OCT-4 antibodies. Results: Twenty-six (84 %) cases (tumors and hyperplasia) were nestin positive with mostly weak, finely granular cytoplasmic staining. Four (13 %) were negative, 1 (3 %) not interpretable. Vimentin was expressed in twenty-seven (87 %) cases. Seventeen (55 %) were focally keratin positive. Only three (10 %) showed OCT-4 positivity. All were GAFP negative. Conclusion: In Leydig cell hyperplasia, adenomas and malignant tumors nestin and vimentin are expressed frequently, sometimes with keratin. This would be a sign of epithelialmesenchymal transition. Further investigations are needed to understand the relationship with the malignant potential of these tumors.