Application of plastic embedding to fine needle aspiration biopsy

OBJECTIVE: To explore the possible advantages that plastic embedding offers to fine needle aspiration biopsy (FNAB). STUDY DESIGN: A series of 54 FNABs was fixed in Kryofix (30 cases) and acetone (24 cases), plastic embedded and cut using a rotative microtome. The 2-μm sections obtained were May-Grunwald-Giemsa and Papanicolaou stain in all cases; mucicarmine, Alcian Blue, periodic acid-Schiff (PAS), PAS-diastase and Feulgen stain for DNA cytometric evaluation were also applied in five cases. Immunocytochemical staining using the antibodies cytokeratin 1-8, epithelial membrane antigen, vimentin, Ki-67, lysozime, calcitonin and carcinoembryonic antigen was carried out with the immunoalkaline phosphatase method. RESULTS: The fragments in the sections were perfectly two dimensional; the architectural features of the original tissues were preserved. Morphologic details of nuclear membranes, nucleoli and mitotic figures were excellent. Cytochemical and immunocytochemical stains were successful in all cases. Immunostains showed the precise location of the signal (nuclear, nucleolar or cytoplasmic), a clear background and preservation of morphology. CONCLUSION: Plastic embedding can be applied to FNAB to solve the problem of dense cellular groups, to study structural and cellular details, and to capitalize on the diagnostic material available for serial cytochemical quantitative and immunocytochemical purposes.