Improved Detection of Adenocarcinoma of Serous Fluids with p53 Immunocytochemistry

OBJECTIVE: To investigate the potential value of p53 protein immunostaining in identifying malignant cells in serous fluids. STUDY DESIGN: We applied p53 immunostaining to 26 cytologicall y malignant, 8 suspicious and 34 benign specimens of serous fluids from 68 patients. For comparison, staining for carcinoembryonic antigen (CEA) was also done on all the specimens. RESULTS: CEA was positive in 23 of 26 (88%) cytomorphologically malignant, 3 of 8 (38%) suspicious and 1 of 34 benign cases, p53 Nuclear immunostaining was positive in 12/26 (46%) malignant, 2/8 (26%) suspicious and no benign cases. Correlation between p53 staining and serous fluid type (benign, suspicious or malignant) was significant. The P based on Fisher's exact test was <.0001. Two cases that were reported cytomorphologically as suspicious stained positively with p53; further investigation in those cases confirmed the diagnosis of metastatic adenocarcinoma. CONCLUSION: p53 Immunostaining of serous fluids seems to be of value in identifying carcinoma cells, especially in those cases that show inconclusive or bland cytologic features. Combining p53 with CEA immunostains in clinically or cytologically suspicious cases may assist in recognition of carcinoma cells and in pursuing an appropriate therapeutic approach.