Primary breast lymphomas are rare. They are defined by the involvement of one or both breasts. This is the first site affected or mainly affected with the exception of ipsilateral axillary involvement. Due to the absence of specific clinical and radiological signs, the diagnosis is confirmed by histology. The most frequent entity remains diffuse large B-cell lymphomas. The place of surgery remains exclusive in establishing the initial diagnosis. Anthracyclinebased chemotherapy with or without Rituximab remains the gold standard in the therapeutic arsenal. We present the case of a 42-year-old woman with no surgical history; nulliparous; followed in nephrology for chronic renal failure, received as an outpatient for a nodule in the left breast in a context of dyspnea. This is a nodule discovered incidentally during a routine examination. Clinical examination of the left breast found nipple retraction without ulceration; a mass 7 cm in diameter located in the left upper outer quadrant. Breast ultrasound and mammography suggest a suspected lesion of malignancy. After a percutaneous micro biopsy; the histological study confirms the diagnosis of a large B-cell lymphoma of the left breast. A TAP CT scan is performed as part of the extension assessment. Chemotherapy based on R-CHOP with local radiotherapy is decided in CPR.