Bilateral Primary Breast Lymphoma Masquerading as Breast Carcinoma: A Rare Case Report

Abstract Primary breast lymphoma (PBL) is a rare entity, accounting for roughly 0.5% of all primary breast tumors. It commonly presents as a lump, which is frequently confirmed based on histopathological findings, as it is difficult to differentiate from other breast primaries on imaging. On histopathology, the most common subtype is diffuse large B-cell lymphoma (DLBCL). Prognostic factors are age, histological grade, and stage at diagnosis. We report a case of a 44-year-old female, who came to us with a painless lump in her left breast, after having a modified radical mastectomy for a similar lump in the opposite breast, under the suspicion of carcinoma breast, 25 days ago. Postoperative histopathology report from the right breast was positive for DLBCL, similar to a tru-cut biopsy from the left breast. 18-Fludeoxyglucose-positron emission tomography (PET) scan was done, which showed no avid lesions in any other organs. The patient was started on an RCHOP chemotherapy regimen. She responded very well to the treatment. After 4 years, the patient remains disease free with no evidence of any recurrence in yearly follow-up PET scans. Awareness and clinical suspicion of PBL are critical for rapid and precise diagnosis to avoid unnecessary surgery and better treatment outcomes.