Encapsulated papillary carcinoma (EPC) is a recognised special type of breast carcinoma. Despite compelling evidence indicating its invasive nature, although not of a conventional form, current consensus opinion is to manage EPC as an in situ disease based on its indolent clinical behaviour. Although most EPC are recognised to be low and intermediate grade, a distinct proportion of these tumours do show high cytonuclear grade features. The existence and behaviour of these rare high grade variants remains to be defined. In this study, we have identified 12 high grade EPC without associated conventional stromal invasion. To further characterise these high grade tumours, a series of invasive papillary carcinoma (n=30) was assessed for coexistence of EPC. Literature was also reviewed.
RESULTS: Approximately 3% of pure EPC exhibit high grade features as defined by nuclear pleomorphism and increased mitotic activity. These tumours not only show histological features associated with aggressive behaviour but also are often hormone receptor negative, tend to be of larger size and more frequently associated with stromal invasion. Of the 10 patients with follow up data, one with pure high grade EPC developed recurrence and died of her disease.
CONCLUSION: High grade EPC is rare and its histological features and more aggressive clinical behaviour suggest that consideration should be made to managing it in a similar fashion to conventional forms of invasive breast carcinoma based on established clinic-pathological parameters. This article is protected by copyright. All rights reserved.