Breast lymphoma refers to involvement of the breast with lymphoma.
Breast lymphomas can be either primary or secondary. Both are rare accounting for 0.3 - 1.1 % of all breast malignancies.
Primary lymphoma of the breast is less common than secondary lymphoma, and is typically a B cell type non-Hodgkin's lymphoma (NHL). Primary non-Hodgkin’s lymphoma of the breast representing only 0.12 - 0.53% of all reported malignant breast tumors.
For a tumor to be labeled as a primary breast lymphoma it is required to fulfill the following criteria 5:
- mammary and lymphatic infiltration should be in close proximity
- adequate pathological evaluation
- exclusion of previous extra-mammary or systemic lymphoma
The axillary nodes are often large. It may present either as a palpable mass or as diffuse thickening of the breast.
There is no single imaging finding diagnostic of lymphoma, it can have variable mammographic appearances but usually it manifests with a diffuse marked increase in parenchymal density (often can be bilateral). The sonographic appearance is most often that of a solid hypoechoic mass which is again non specific; both radiologic and clinical appearance are similar to carcinoma and therefore the differential diagnosis is difficult. Microcalcifications are not a usual feature in lymphoma.