Identification of types and primary sites of malignant tumors by examination of exfoliated tumor cells in serous fluids. Comparison with the diagnostic accuracy on small histologic biopsies.

The accuracy of identification of tumor type and primary site of malignant tumors by examination of exfoliated tumor cells was cytologically studied in 448 malignant effusions from 366 patients for whom the primary tumor site had been confirmed by histology. Ninety-seven corresponding small biopsies from metastases were separately reviewed histopathologically. In four fluids, the cells were too scanty or too poorly preserved for tumor typing. The cytologic tumor typing was performed with nearly 100% accuracy in the remaining 444 fluids, except for those of intermediate-cell anaplastic carcinomas (0 of 3) and poorly differentiated squamous (epidermoid) carcinomas (1 of 5). Adenocarcinoma was correctly identified in 98% of 285 fluids, large-cell carcinoma in 97% of 108 fluids, oat-cell carcinoma in 94% of 16 fluids, well-differentiated (keratinizing) squamous carcinoma in 100% of 3 fluids, malignant lymphoma in 100% of 22 fluids and sarcoma in 100% of 2 fluids. The criteria and the failures are discussed at length. In the investigation of the accuracy of cytologic and histologic diagnoses with respect to the primary tumor site, tumors with variable sites of origin (sarcomas and lymphomas) and those with usually singular sites of origin (e.g., small-cell anaplastic carcinoma of the lung) were excluded, leaving 387 cytologic and 83 histologic specimens available for review. The breast as a primary site was correctly identified in 70% of both the cytologic and histologic specimens; the primary cytodiagnostic criteria included a uniform cell pattern, finely granular chromatin, dense cytoplasm and cell balls with smooth borders. Ovarian primaries were correctly identified in 70% of the fluids and 83% of the biopsy samples on the basis of very irregular clusters of large pleomorphic tumor cells, large nucleoli and psammoma bodies. Lung primaries, identified in 50% of the fluids and 29% of the biopsy samples, showed quite variable cell patterns, most often including large pleomorphic cells with or without mucus formation and prominent multinucleation. Gastric cancers of the diffuse type were accurately identified in 52% of the corresponding fluids, which showed mainly isolated cells with dense cytoplasmic rims, occasional signet-ring cells, "embryo-shaped" nuclei, marked hyperchromasia and densely granular chromatin.(ABSTRACT TRUNCATED AT 400 WORDS)