[A Case of Primary Breast Diffuse Large B-Cell Lymphoma in a Male Patient].

The patient was a 68-year-old man who presented with a progressively enlarging mass in the left breast. Breast ultrasonography revealed an irregular hypoechoic mass in region E of the left breast. A core needle biopsy (CNB) revealed diffuse large B-cell lymphoma (DLBCL). Positron emission tomography-computed tomography (PET-CT) showed no abnormal uptake in organs outside the breast, and bone marrow examination revealed no involvement. The patient was diagnosed with primary DLBCL in the breast. Surgical resection was chosen for both a definitive diagnosis and because the patient experienced pain due to the rapid enlargement of the tumor. Postoperatively, polatuzumab vedotin and R-CHP (Pola + R-CHP) were administered.