Chronic lymphocytic leukemia mimicking recurrent carcinoma of the breast: case report and review of the literature.

Secondary localization of chronic lymphocytic leukemia (CLL) in breast is rare, while concurrent invasive ductal carcinoma and CLL manifesting as a collision tumor in breast is extremely rare. The observation of a CLL infiltration closely associated with a distinct breast neoplasm with the absence of any other localization for the leukemia is an indisputable argument for a relationship between the two diseases. The presence of both tumors is not simply due to chance. This association (CLL and carcinoma) has also been described in other organs. Hereafter, we report a second case of an 80 year-old woman in whom a leukemic infiltrate was confined to the region immediately surrounding poorly differentiated primary breast carcinoma, and we will discuss the association between CLL and carcinoma.