Immunoperoxidase staining of fine needle aspiration specimens previously stained by the Papanicolaou technique
The use of immunoperoxidase techniques was investigated in 21 fine needle aspiration (FNA) cytology smears that had been previously stained by the Papanicolaou technique. The retrospectively selected slides were destained before applying the immunostain, utilizing antisera to calcitonin, prostatic acid phosphatase (PrAP), prostate-specific antigen (PSA), alpha-lactalbumin (AL), S-100 protein (S-100), carcinoembryonic antigen (CEA), common leukocyte antigen (LA), epithelial membrane antigen (EMA) and alpha-fetoprotein (AFP). Positive results were obtained with six of nine small-cell carcinomas of the lung stained with EMA, all three colonic carcinomas stained with CEA, one of two prostatic carcinomas stained with PSA and PrAP, one of two lymphomas stained with LA and the one medullary thyroid carcinoma stained with calcitonin. Negative staining results were observed in the one melanoma stained with S-100, the two breast carcinomas stained with AL and the one hepatocellular carcinoma stained with AFP. These results indicate that immunostaining can be a helpful diagnostic tool in diagnosing some fine needle aspirates using smears previously stained with the Papanicolaou stain.