A Study of Myoepithelial Cells in Fine Needle Aspirates from Breast Lump Using Antibody to p63

Abstract

Background: Myoepithelial cells of the mammary gland are considered to be a key in distinguishing benign from malignant disease in fine-needle aspiration cytology (FNAC). p63 decorates the nuclei of myoepithelial cells. In view of this, present study was undertaken to study the difference in number of myoepitheal cells in various breast lesions using anti p63 immunocytochemistry. Methods: This study was conducted on 50 patients presenting with breast lump. FNA was done, smears prepared were stained with May Grunwald Giemsa and subjected to immunocytochemistry for p63. MGG stained smears were subjected to quantitative estimation of myoepithelial cells per 1000 ductal cells. Percentage of cell clusters showing p63 positive cells were noted. Only the nuclear immunoreactivity for p63 was considered specific. Result: Maximum number of cases (26) were in 20-29 years age group (55.3%).The mean number of myoepithelial cells in the benign lesions was 196.8 while ductal carcinoma had a mean of 5.8.The difference between the mean of myoepithelial cells/1000 ductal cells was found to be statistically significant (t-value 4.51 and p-value .000048). The difference in p63 immunostaining between benign and malignant lesions was also found to be statistically significant (for positivity of p63 at 0% and > 75% p value <0.001). Conclusion: We hereby conclude that myoepithelial cells are a key to distinguish benign from malignant lesions in FNAC. Their sensitivity is increased by staining with p-63 antibody. We also conclude that presence of more than 74% positive cell clusters is strongly suggestive of benign lesions.