RESUMO
Primary breast lymphoma (PBL) is considered a rare clinical entity forming about 0.4%-0.5% of all breast tumors. In this report we have presented a case of PBL in a 56-year-old female complaining of a mass in the upper medial quadrant of the breast. PBL suspicion of our case was made by breast radiology and the sure diagnosis was reached by the immunohistochemistry results; CD (cluster of differentiation) 20: was diffusely positive; Pan-CK (pan-cytokeratin): was diffusely negative in tumor cells. Hence, the case was finally diagnosed as a primary breast a primary breast diffuse large B-cell non-Hodgkin's lymphoma of lymphoma. The management and outcome of PBL and carcinoma are totally different. Accurate diagnosis of PBL by true cut needle biopsy and immunocytochemistry is important to avoid unnecessary mastectomies.