Efficacy of immunohistochemistry in diagnosing papillary lesions of the breast
Dr. Sunanda Jennifer G, Dr. Nalinimohan C, Dr. Shailaja Prabhala and Dr. Ashok Kumar Deshpande
Papillary neoplasms of breast form a heterogeneous group of diseases, spanning a spectrum of benign, atypical, and malignant lesions constituting less than 10% of benign lesions and less than 1% of breast cancers.
Aim of the study: To differentiate and determine the behaviour of papillary lesions of the breast based on immunohistochemical staining pattern by CD10, Smooth Muscle Actin and p63.
Materials and Methods: A total of 15 cases of papillary lesions which included intraductal papillomas, papillary epithelial hyperplasia, papillary carcinomas, micropapillary ductal carcinoma in situ [DCIS] were evaluated by CD10, SMA and p63 immunostains.
Results: Out of the 15 cases, 5 diagnosed as duct papillomas showed positivity for all the three markers. 6 cases diagnosed as papillary carcinomas were uniformly negative for all stains. 4 cases diagnosed as papillary epithelial hyperplasia showed discontinuous variable staining with p63, making interpretation of an intact myoepithelial cell layer difficult. The lack of a basal myoepithelial cell layer in these cases suggests progression to invasive disease and explains distant metastases from previously reported “intraductal papillary carcinoma.”
Conclusion:It is prudent to use p63, which is a nuclear marker and does not show cross reactivity with stroma, proving to be better in differentiating the papillary lesions of breast unlike CD10 and SMA which stain the cytoplasm of myoepithelial cells and show cross reactivity with the mammary stroma.