BACKGROUND: Primary breast lymphoma (PBL) is an unusual clinical entity accounting for 0.4–0.5% of all breast neoplasms. The usual presentation includes a painless palpable mass similar to that of breast carcinoma. Diffuse large B-cell lymphoma (DLBCL) is the most common identifiable type of PBL based on the histopathological examination.

CASE REPORT: We report an unusual case of a 43-year-old Indonesian woman who presented with a 7-month history of a painless mass in the left breast. A core needle biopsy revealed diffuse infiltration of large atypical lymphoid cells. The immuno-histochemical biomarkers confirmed the diagnosis of a DLBCL. A bone scan showed no evidence of bone metastasis. It was treated non-surgically, based on the decision of the breast multidisciplinary team (MDT). The patient was treated with 4 cycles of combination chemotherapy with R-CODOX/IVAC. A follow-up PET scan revealed non-significant mild F-18 fluorodeoxyglucose (FDG) uptake at the periphery of the residual left breast mass, indicating a radiologically favorable response.

CONCLUSIONS: Early and accurate diagnosis of PBL is crucial for selecting the appropriate MDT treatment strategies to avert potentially harmful surgical interventions.

Keywords: Breast Neoplasms - therapy, Lymphoma, Large B-Cell, Diffuse - therapy