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Background
Lymphoma and leukemia are infrequently encountered in the breast. For instance, lymphomas account for 0.4%-0.7% of breast malignancies. A bimodal age distribution is demonstrated in breast lymphomas, with peaks in the 4th and 7th decades of life. Breast lymphomas are classified as primary and secondary, with secondary involvement of the breast being more common. B-cell lymphoma manifests more frequently than T-cell lymphoma, with diffuse large B-cell lymphoma constituting the most common subtype. In cases of leukemia, axillary lymph node enlargement is frequently seen with chronic lymphocytic leukemia, but involvement of breast parenchyma is rare, with painless palpable masses occurring with acute leukemia.

Educational Goals / Teaching Points
To discuss common mammographic, sonographic and cross-sectional imaging features of hematologic breast malignancies. To provide a case-based review of rare subtypes of breast lymphoma and secondary breast involvement in leukemia. To evaluate the role of imaging in the diagnosis and management of hematologic malignancies in the breast.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
On mammography, breast lymphomas appear as solitary or multiple, noncalcified, round or oval masses that may have circumscribed to indistinct margins. Parenchymal and skin thickening may occur due to diffuse involvement. Bilateral axillary adenopathy suggests secondary involvement. Ultrasound demonstrates hypoechoic solid masses with circumscribed to irregular margins, posterior acoustic enhancement, and (frequently) an echogenic rim. In the case of a 64 year old women, who presented for diagnostic evaluation of a screening detected right breast mass, a primary follicular lymphoma of the breast was diagnosed. However, rare histopathological subtypes may not follow the described pattern, such as in the case of a 33 year old women with history of seizure disorder controlled with Tegretol, who palpated a lump in the left breast after trauma to the area. The imaging finding was described as probable fat necrosis and an ultrasound examination in 6 months was recommended. Follow-up imaging revealed interval increase in size of a fat-containing focal asymmetry with architectural distortion. Ultrasound-guided biopsy yielded a primary subcutaneous panniculitis-like T-cell lymphoma, possibly related to chronic Tegretol use. The most common mammographic manifestation of leukemia is axillary adenopathy, but parenchymal involvement may range from solitary or multiple masses to diffusely increased breast density. Ultrasound demonstrates mixed echogenicity oval or irregular masses with hypoechoic centers, and indistinct or microlobulated margins. In the case of a 22 year old women with history of refractory B-cell (Ph-) acute lymphoblastic leukemia (ALL) who palpated a left breast mass, mammography and ultrasound demonstrated multiple contiguous masses. Biopsy confirmed B-cell ALL involving the breast.

Conclusion
Diagnosis of hematologic breast malignancies involves a multi-modality approach, with mammography, ultrasound, and PET/CT, which is critical for diagnosis and treatment planning.