Localization of p53 and proliferating cell nuclear antigen in fine-needle aspirates of benign and primary malignant tumors of the human breast: An immunocytochemical study using supersensitive monoclonal antibodies and the biotin-streptavidin-amplified method

p53 and proliferating cell nuclear antigen (PCNA) status was determined in fine-needle aspirates (FNAs) and methacarn-fixed paraffin-embedded tissue sections of six fibroadenomas and 50 primary breast carcinomas using supersensitive monoclonal antibodies and the biotin-streptavidin-amplified method. Nuclear accumulation of p53 was identified in 28% of carcinomas, while a heterogeneous immunostaining for PCNA was seen in all benign and malignant tumors examined. p53 expression in relation to nuclear pleomorphism and lymph-node status showed weak correlation only as to nuclear grade (r = 0.28; P < 0.01). No direct or inverse correlation was found to exist between PCNA score and the evaluated prognostic parameters. In conclusion, although the identification of p53 in FNAs of breast tumors may assist in the diagnosis of malignancy, its application in the laboratory practice of cytopathology appears to be limited, since only 28% of primary breast carcinomas accumulate p53. Moreover, PCNA immunocytochemistry can be used as an alternative to traditional methods of evaluating the proliferative rate of tumors in FNAs.