Cytopathology of exocrine pancreatic carcinoma in effusions.

The cytomorphologic features were analyzed in 26 fluid samples (18 peritoneal and 8 pleural fluids) obtained in vivo from 20 patients with pancreatic carcinoma. All tumors were ductal adenocarcinomas, as proven histologically on autopsy samples. The basic cytomorphologic pattern in the smears was that of a malignant glandular tumor, consisting of cell groups with various degrees of cohesiveness. The most prominent feature was a linear arrangement (the so-called "Indian file") of tumor cells showing nuclear molding; these aggregates were frequently closely associated with the flat round clusters of cells. Other nonspecific features of adenocarcinoma included eccentric hyperchromatic nuclei, abundant, often well-preserved vacuolated cytoplasm, a variable amount of fibrin and a reactive background. Review of the autopsy specimens also revealed the presence of an "Indian-file" pattern in most cases, especially when a conspicuous desmoplastic reaction was present. These findings suggest that pancreatic carcinoma should be included in the differential diagnosis of positive serous effusions showing these cytomorphologic features.