Encapsulated Papillary Carcinomas of Breast, The Enigmatic Lesions

Encapsulated papillary carcinoma (EPC) is a rare entity among breast malignancies that accounts for < 1- 2 %. Even though they lack distinct myoepithelial layer they are considered as an in-situ carcinomas unless associated with invasive component. Because of overlapping features in benign and malignant conditions, the accurate subcategorization of these lesions is difficult despite of the papillary architecture, commonly leading to misdiagnosis and improper treatment. EPC is a slowly growing tumor with a thick peripheral fibrous capsule and proliferating cell structure with a supporting fibrovascular stalk. It is a unique tumor with the characteristic feature of myoepithelial layer absence both in capsule and in the papillae. Materials and Methods: A retrospective analysis of all the cases reported as encapsulated papillary carcinomas in the department of pathology over a period of 5 years was done. The H & E-stained slides were reviewed based on architectural features along with detailed clinical history. Histological grading was done. Immunohistochemical staining was done to visualize the presence or absence of myoepithelial layer. ER, PR and HER2/neu staining was done to find out the hormonal status of the tumor. Results: The total number of breast lesions were 288 over a period of 5 years. Among them 62 (21.5%) were breast malignancies. Six cases (10 %) out of 62 breast malignancies were encapsulated papillary carcinomas. Forty-three (15%) out of total breast lesions (288) were Papillary neoplasms. Of the 43 papillary lesions 14% were encapsulated papillary carcinomas. The average age of patients in encapsulated papillary carcinomas was 47 years. The average tumor size was 2.2 cms. Five cases (84%) were of histological grade 1 and 1 case (16%) showed grade 2. Myoepithelial layer was absent in all the 6 cases (100%). Of the 6 cases, 5 patients were positive for hormonal receptors (ER and PR) and negative for HER2/neu. Only 1 case (16%) with invasion showed negative for all receptors. Conclusion: Encapsulated papillary carcinomas need to be thoroughly investigated for nuclear grade and invasion in order to avoid over treatment. In the absence of invasion encapsulated papillary carcinomas have very good prognosis. Keywords: Encapsulated, papillary, breast, grade, myoepithelial layer, invasion, in situ, prognosis, hormone receptors.