Bilateral Primary Marginal Zone Lymphoma of the Breast - A Rare Breast Malignancy.

Extranodal marginal zone lymphoma (EMZL) presents only rarely within the breast, although the incidence of breast EMZL has increased in the past decade for unclear reasons. Due to its rarity, the etiology, course, and treatment response of this cancer are less studied. Case Report: We present the case of a 64-year-old female who had bilateral diffuse irregularity in a trabecular pattern on screening mammogram. Random ultrasound-guided breast biopsy of the right breast demonstrated an extra-nodal marginal zone B-cell lymphoma. She also had approximately 25% marrow involvement by mucosa-associated lymphoid tissue-type marginal zone lymphoma and splenomegaly. Clinically she remained asymptomatic during a 1-year follow-up. Although she presented with advanced-stage disease involving both breasts, spleen and bone marrow, given her lack of associated symptoms, she was observed with active surveillance. Conclusion: Asymptomatic cases of breast EMZL can be managed with close observation as exemplified by our case.