A 46-year-old male presented with a lump in the right breast with right axillary lymphadenopathy; a biopsy with immunohistochemistry showed neoplastic cells positive for CD 20 and negative for CD 30, epithelial membrane antigen, anaplastic lymphoma kinase, suggestive of diffuse large B cell lymphoma stage IIEA. The gene discussed is MUC1; the disease is diffuse large B-cell lymphoma.