Fifty fine-needle aspiration cytologies of breast that were diagnosed
as carcinomas were retrieved from the files and retrospectively evalua
ted for the expression of c-erbB-2 oncoprotein using standard immunocy
tochemical methods. Corresponding histologic sections of all tumors we
re similarly studied. Seventeen fine-needle aspirates (34%) reacted po
sitively for the presence of c-erbB-2 oncoprotein. All but one (32%) o
f the corresponding tissue sections were also positive for c-erbB-2 by
immunohistochemistry. All positive cases were infiltrative ductal car
cinomas with a preponderance of the comedo type. Positive reactions we
re localized in the cytoplasmic membrane of rumor cells. The staining
was either present in all cells throughout a tumor, or it was complete
ly absent. We conclude that immunocytochemistry for c-erbB-2 oncoprote
in can be performed on fine-needle aspiration cytology samples that ar
e previously fixed and stained with the Papanicolaou technique. Furthe
rmore, the sensitivity of immunostaining results are comparable to tha
t obtained in histologic sections. (C) 1994 Wiley-Liss, Inc.