Availability of immunocytochemistry using cocktail antibody targeting p63/cytokeratin14 for the differential diagnosis of fibroadenoma and ductal carcinoma in situ in fine needle aspiration cytology of the breast.

ABSTRACT

OBJECTIVE: The differential diagnosis of fibroadenoma (FA) and ductal carcinoma in situ (DCIS) has been problematic in fine needle aspiration biopsy (FNAC) because it has been difficult to differentiate between the "large epithelial clusters" associated with FA and those associated with DCIS. The purpose of this study was to prospectively validate the usefulness of immunocytochemical staining using cocktail antibody targeting p63/CK14 in the differential diagnosis of FA and DCIS. MATERIALS AND METHODS: Twenty patients diagnosed as having an uncertain malignant potential (indeterminate) for breast cancer on the basis of a FNAC finding were selected randomly ten patients with FA and ten with DCIS. The cover glass on a specimen stained with the Papanicolaou stain on a glass slide was peeled off, and the specimen was restained by immunocytochemical staining of cocktail antibody targeting p63 and CK14. RESULTS: Six of the twenty patients were CK14-immunopositive FA, 6; DCIS, 0. The remaining patients were CK14-immunonegative FA, 4; DCIS, 10. The number of CK14-immunopositive DCIS patients was significantly different from that of FA patients (P=.0054). Eight out of the twenty patients were p63-immunopositive FA, 8; DCIS, 0. The remaining patients were p63-immunonegative FA, 2; DCIS, 10. The number of p63-immunopositive DCIS patients was significantly different from that of FA patients (P=.0004). CONCLUSIONS: Immunocytochemical staining using cocktail antibody targeting p63/CK14 was useful for the differential diagnosis of FA and DCIS in FNAC of the breast.