The positive peritoneal effusion. A retrospective study of cytopathologic diagnoses with autopsy confirmation.

The distribution of 215 malignant tumors responsible for peritoneal effusions was investigated with respect to cytohistologic correlation and autopsy features. In males, cancer of the gastrointestinal tract, pancreas and liver were the most frequently observed forms, whereas in females tumors at gynecologic sites far outnumbered other neoplasms, such as stomach, bowel, pancreas, gallbladder and liver cancer. Cells from extra abdominal tumors, consistently seen in positive ascitic effusions, were from pleural mesothelioma and breast carcinoma, respectively, in males and females. The first diagnosis of malignancy rested on cytologic material in about 57% of cases in both sexes. In females, however, cancers of the ovary were discovered only cytologically in about two-thirds of cases. Occasionally, cancers of the uterine cervix and endometrium were diagnosed initially on peritoneal fluid. Morphologic diagnosis of pancreatic cancer was rendered on a cytologic specimen in all cases. The results of this study are useful reference data for cytologists dealing with positive effusions, especially due to unknown primary neoplasms.