Encapsulated Papillary Carcinoma of Breast: Clinicopathological Features and Prognostic Parameters

Introduction Encapsulated papillary carcinoma (EPC) is a rare malignant papillary breast tumor that, despite a lack of distinct myoepithelial layer, is considered an in situ carcinoma unless associated with a frank invasive component. Data regarding clinicopathologic features of rare breast tumors like EPC are especially scarce. Therefore, in this study, we evaluated the clinicopathologic features of EPC and performed a clinicopathological comparison with conventional invasive ductal carcinoma (IDC). Methods It was a retrospective study conducted in the Department of Pathology, Liaquat National Hospital and Medical College, from January 2013 to December 2019 over a period of seven years. During this period, 16 cases were diagnosed as EPC, and 634 cases were labeled as IDC. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2/neu) immunohistochemical (IHC) stains were performed on both EPC and IDC cases. Moreover, myoepithelial IHC stains were performed on all cases of EPC. Clinicopathologic features of EPC were compared with IDC. Results The mean age of the EPC patients was 51.81±13.94 years, with a mean tumor size of 2.97±2.46 cm. The majority of cases were grade II, and axillary metastasis was present in 18.8% of cases. About 56.3% of cases were in situ, and 43.8% showed foci of invasion in the form of IDC. Recurrence was noted in 12.5% of cases with a survival rate of 93.8%. ER, PR, and HER2/neu positivity was noted in 81.3%, 75%, and 12.5% cases, respectively. EPC was significantly noted to have lower tumor grade and pathological T-stage than IDC. Similarly, a lower frequency of axillary metastasis was noted in EPC than IDC.  Conclusion EPC is a rare distinct subtype of papillary breast tumors with overall good survival and low recurrence rate. Compared to IDC, we found EPC to be associated with better prognostic parameters such as lower tumor grade and T-stage and lower frequency of axillary metastasis.