Primary breast diffuse large B-cell lymphoma mimicking breast carcinoma: a case report

Abstract

Background Primary breast lymphoma (PBL) is an exceedingly rare extranodal malignancy that frequently mimics breast carcinoma on clinical and radiological examination, posing a significant diagnostic challenge. Case presentation We report a case of a 39-year-old Chinese woman who presented with two palpable right breast masses. Imaging revealed suspicious lesions classified as Breast Imaging-Reporting and Data System 4A, prompting surgical excision and biopsy. Histopathological examination and immunohistochemical (IHC) analysis confirmed a diagnosis of diffuse large B-cell lymphoma, germinal center B-cell subtype. Staging by 18F-fluorodeoxyglucose positron emission tomography/computed tomography established disease as Ann Arbor stage IE, asymptomatic (stage IEA) with an International Prognostic Index score of 0. The patient was initiated on R-CHOP chemoimmunotherapy and demonstrated a favorable response after three cycles, with no evidence of recurrence. Conclusion This case highlights the importance of histopathological and IHC evaluation in differentiating PBL from breast carcinoma. Early and accurate diagnosis is essential to guide appropriate treatment and optimize patient outcomes.