XXXX Staining of myoepithelial cells in breast fine needle aspirates: a study of its role in differentiating in situ from invasive ductal carcinomas of the breast.

@entity876 @entity4206 @entity3821 @entity189
AIMS: One of the limitations of fine needle aspiration biopsy (FNAB) of the breast is @entity189 ( @entity189 ) from @entity3821 ( @entity3821 ). It has been proposed that the presence of myoepithelial cells overlying epithelial malignant cell clusters suggests @entity3821 . However, the recognition of myoepithelial cells in aspirates may be difficult. The aim of this study was to investigate a new nuclear myoepithelial cell marker, @entity4206 , a @entity876 homologue nuclear transcription factor, in a series of breast FNABs in an attempt to distinguish @entity189 from @entity3821 . METHODS: Papanicolaou stained smears from eight cases of pure @entity3821 and 15 cases of pure @entity189 with a histologically confirmed diagnosis were submitted to immunocytochemical analysis using the antibody 4A4 against @entity4206 . Two pathologists evaluated the presence of @entity4206 positive cells overlying malignant cell clusters and admixed with malignant cells. The frequency of @entity4206 positive cells in @entity3821 and @entity189 was compared using Fisher's exact test. RESULTS: @entity4206 consistently stained the nuclei of myoepithelial cells, either overlying malignant cell clusters and/or admixed with malignant cells. @entity4206 positive myoepithelial cells were seen in all @entity3821 cases and in nine of the 15 cases of @entity189 (p = 0.0375). In eight cases (three @entity3821 and five @entity189 ), scattered @entity4206 + epithelial malignant cells were seen. CONCLUSIONS: Although @entity4206 positive myoepithelial cells are found more frequently in @entity3821 cases, their presence cannot be used as a criterion to rule out invasion in breast FNABs because they are present in up to 60% of invasive cases.
