Examination of cytological smears and cell blocks of pleural fluid: Complementary diagnostic value for malignant effusions.

OBJECTIVES: To evaluate the independent usefulness of pleural fluid smear and cell block (CB) preparations for the diagnosis of malignant effusions.

PATIENTS AND METHODS: A total of 632 cytological smears and 554 CBs from 414 consecutive patients with malignant effusions were retrospectively evaluated.

RESULTS: The diagnostic yield of a first specimen was 44% regardless of whether a smear or CB cytologic examination was performed. The use of subsequent separated specimens increased the identification of malignancy to 56%. Overall, 11% of samples found to be negative by cytologic smears showed malignant cells on CBs, whereas 15% of negative CBs were reported as positive on smear slides. Pleural fluid specimens with low red and/or white blood cell counts more frequently resulted in the generation of suboptimal CB preparations.

CONCLUSIONS: If CBs and smears are prepared and examined, the percentage of positive diagnoses will be greater than if only one method is used.