Abstract: The expression of proliferating cell nuclear antigen (PCNA) was studied in 50 cases of squamous cell carcinoma of the skin using immunohistochemistry and PCNA cyclin monoclonal antibody.PCNA staining was found in the nuclei of tumour cells, two types of staining were seen, a granular pattern and a more diffuse nuclear staining.The expression of PCNA showed a significant positive correlation with degrees of differentiation of the carcinoma cells and lymph node metastasis (P<0.05).In some cases the increased expression of PCNA in the tissue adjacent to the tumour may represent the autocrine and paracrine of growth factors of cancer cells which influence the expression of PCNA.

Key words: Carcinoma,squamous cell, Antigen, proliferating cell nuclear