Chronic lymphocytic leukemia and invasive ductal carcinoma presenting as a collision breast tumor

Although breast cancer is the second most common cancer in women, secondary breast involvement by extramammary malignancies is rare, with lymphomas and leukemias being the most common. We present an extremely rare case of a collision tumor in the breast composed of invasive ductal carcinoma, a primary breast cancer, and chronic lymphocytic leukemia (CLL). Imaging findings of CLL within the breast differ from those typically seen in carcinoma-characterized by a nonmass enhancement onmagnetic resonance imaging with type I curve on dynamic subtracted images and as an area of heterogeneous tissue on ultrasound images. In a patient with a history of CLL and an abnormal imaging as described, a biopsy to rule out leukemic involvement is warranted.