Primary and Secondary Breast Lymphoma: Clinical, Pathologic, and Multimodality Imaging Review.

Breast lymphoma is a rare hematologic neoplasm that originates in the breast lymphoid tissue and includes primary breast lymphoma (PBL) and secondary breast lymphoma (SBL). PBL involves the breast lymphoid tissue in the absence of previously identified extramammary lymphoma and widespread disease. SBL is the most common metastasis to the breast, accounting for 17% of metastatic disease to the breast.