Invasive Micropapillary Carcinoma of the Breast with an Encapsulated-Like Pattern: An Unreported Entity?

positive, HER2-negative]. The patient received neoadjuvant chemotherapy, followed by a mastectomy with sentinel lymph node biopsy. The mastectomy revealed a well-circumscribed 11 cm mass surrounded by a fibrous capsule. The tumor consisted of tubulo-micropapillary structures without fibrovascular cores, lined by a single layer of cuboidal cells containing nests of foamy macrophages. Rare foci of lymphovascular invasion were observed. Two sentinel lymph nodes were negative. To our knowledge, invasive micropapillary carcinoma with an encapsulated pattern has not been previously reported.