Proliferating cell nuclear antigen (cyclin) expression in normal and abnormal cervical squamous epithelia.

Expression of Proliferating cell nuclear antigen (PCNA) was evaluated in formalin-fixed, paraffin-embedded normal and abnormal cervical squamous epithelia using immunoperoxidase stains and PC10 monoclonal antibody to PCNA. PCNA was exclusively expressed in the parabasal and basal layers of normal ectocervix and a similar pattern was seen in nine of the 11 cases with squamous metaplasia. Examples of cervical dysplasia showed expression in higher layers of cervical epithelium, corresponding to the degree of dysplasia. Increased staining was seen in condylomas and markedly reduced staining with atrophy. The percentage of basal cells that stained increased progressively from atrophic to normal, to condylomatous, to dysplastic epithelia. Proliferative activity can be satisfactorily assessed in formalin-fixed cervical epithelia using PC10 PCNA antibody. This assessment can be of potential diagnostic use in difficult cases.