Atomic force microscopy in effusion cytology

OBJECTIVE: To investigate whether atomic force microscopy (AFM) in combination with classical light microscopy allows simple identification of surface structures of cells from pleural and ascitic fluids for diagnostic purposes in place of scanning electron microscopy (SEM). STUDY DESIGN: We examined a total of 180 cells obtained from 9 reactive pleural or peritoneal effusions, 14 associated with carcinomatosis from histologically confirmed tumors and 5 from mesotheliomas. Cells of interest were selected in air-dried, uncovered, May Grunwald-Giemsa (MGG)-stained smears and subsequently investigated by AFM. Incorporation of a very compact AFM scanner into the nose piece of a conventional Axioscope light microscope allowed alternating application of both techniques. RESULTS: AFM was able to detect cell surface structures, such as microvilli, phagocytic pits, secretory blebs and lytic holes. The image resolution was sufficient but not its good as that with SEM. We found differences in number, length and diameter of microvilli between cells from mesotheliomas and from metastatic adenocarcinomas. CONCLUSION: As AFM can be carried out in combination with light microscopy quickly and easily on uncovered, MGG-stained smears, we propose this method as a suitable tool for obtaining additional useful information in routine cytologic diagnosis of effusions.