Filtration and agar embedding applied to fine needle aspirates for tumor diagnosis by electron microscopy. A combined technique.

OBJECTIVE: To develop a novel method for processing of fine needle aspirates subjected to electron microscopic (EM) study. STUDY DESIGN: Included 70 cases of poorly differentiated malignant tumors in which a definitive diagnosis was not possible on light microscopic (LM) examination and that thus required application of an ancillary technique such as FNA/EM, for diagnosis. We have established a novel method of processing, a technique of filtration through nylon mesh filters to eliminate red blood cells (RBCs) and necrotic debris, followed by agar well embedding to avoid loss of diagnostic material during processing without centrifugation at later steps after agar embedding, thus minimizing the time required for processing. It was successfully carried out in 70 cases. RESULTS: The combined technique was extremely effective in eliminating RBCs and necrotic debris. It also avoided further loss of valuable diagnostic material. An accurate diagnosis was rendered in 70 cases; that was not possible by LM alone. The whole procedure saves two to three hours of processing as centrifugation is not required after the agar embedding step. CONCLUSION: This technique was found to be cost- and time-effective, particularly suitable for developing countries, where financial resources are limited.