Confocal microscopy of false-negative breast aspirates.

Even when using a novel optimized FNA-21 for breast fine-needle aspiration biopsy, our series of 163 breast lesions with consecutive histology, including 110 carcinomas, contained eight cancer cases with a negative cytologic diagnosis. Two consisted exclusively of thick, undiagnosable epithelial fragments and were devoid of detached malignant cells on which the proper diagnosis could have been made. Optical sectioning of the original smears by the confocal microscope allowed us to reclaim from these epithelial fragments the diagnostic abnormal chromatin patterns, even in the air-dried smears. In the thin optical sections the cancerous tubular or cribriform growing pattern was visualized. The high spatial resolution of the confocal microscope can be further exploited with the application visualization system (AVS). The AVS three-dimensional reconstructions allow us to see the surface of these malignant cells in a detail approaching that of scanning electron microscopy. Furthermore, the internal aspects of the malignant nuclei can be visualized with these techniques.