Electron Microscopy of Encapsulated and Solid Papillary Carcinomas, Is This an In-Situ or an Invasive Entity?
Background: for long time encapsulated and solid papillary carcinomas have been debated either an in-situ or an invasive entity. The goal of our study was to examine the presence or absence and the quality of myoepithelial cells, the presence or absence and thickness of basement membrane in all the selected cases.
Methods: 8 cases of encapsulated and solid papillary carcinomas, 3 cases of low to intermediate grade DCIS in association with low grade IDC NOS and 2 cases of combined IG DCIS and encapsulated papillary carcinomas as well as 2 cases of normal breast were selected from your database. The morphology was reviewed, immunohistochemical stains to highlight myoepithelial cells were performed and all cases were subjected for digital electron microscopy.
Results: All 5 cases of encapsulated papillary carcinoma show the presence of continuous or discontinuous attenuated basement membrane and absence of myoepithelial cells, 3 solid papillary carcinomas show possible small myoepithelial cells.
Conclusions: We think that encapsulated papillary carcinomas represent a category of neoplasms in transition from an in-situ to invasive carcinomas, and at this stage should be interpreted as low grade invasive ductal carcinomas with favorable behavior. Solid papillary carcinomas should be divided into 2 categories: an invasive solid papillary carcinoma and in-situ solid papillary carcinomas.