Medullary carcinoma may refer to one of several different tumors of epithelial origin. As the term "medulla" is a generic anatomic descriptor for the mid-layer of various organ tissues, a medullary tumor usually arises from the "mid-layer tissues" of the relevant organ.

Medullary carcinoma of the breast is a subtype of invasive ductal carcinoma. It is a type of breast cancer that begins in the milk ducts. ... Medullary carcinoma is usually less likely to spread to the lymph nodes and more responsive to treatment than the more common types of invasive breast cancer