Special Types of Invasive Breast Carcinoma

Breast carcinoma is a vastly heterogeneous disease encompassing a wide array of entities with different morphology, biology, clinical behavior, and prognosis. Special types of breast carcinoma include tumors with morphologies that deviate from invasive carcinoma of no special type (NST). As a group, special types comprise up to 25% of all breast cancers, and encompass entities ranging from low to high-grade, and with different hormone receptor and HER2 status. The recognition of the different special types of breast cancer is of paramount importance, as their proper classification is relevant not only for taxonomic purposes, but has also for therapeutic implications.