Abstract
Rationale:
Primary breast diffuse large B-cell lymphoma (PB-DLBCL) is a rare extranodal manifestation of non-Hodgkin lymphoma (NHL) that can closely resemble breast carcinoma clinically and radiologically. This overlap may delay accurate diagnosis and appropriate treatment. We report a case of PB-DLBCL in a postmenopausal woman whose initial multimodal imaging findings were suspicious for breast carcinoma, but whose final diagnosis was established by core needle biopsy with immunohistochemical and molecular evaluation.
Patient concerns:
A 59-year-old postmenopausal woman presented with a painless, palpable mass in the right breast that had been present for approximately 3 weeks.
Diagnoses:
Breast ultrasonography, mammography, magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) demonstrated a suspicious right breast mass with ipsilateral axillary lymphadenopathy, initially raising concern for breast carcinoma. Ultrasound-guided core needle biopsy showed diffuse infiltration by atypical lymphoid cells. Immunohistochemistry confirmed a B-cell phenotype, and fluorescence in situ hybridization (FISH) showed no MYC, BCL2, or BCL6 rearrangements. Bone marrow biopsy showed no evidence of marrow involvement. The final diagnosis was PB-DLBCL, non-germinal center B-cell-like (non-GCB) subtype, Ann Arbor stage IIE.
Interventions:
The patient received 6 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemoimmunotherapy. No breast-directed surgery, consolidative radiotherapy, or central nervous system prophylaxis was administered.
Outcomes:
At 6 weeks after completion of R-CHOP therapy, PET/CT showed complete metabolic resolution of the right breast lesion, with only a residual punctate calcified focus measuring approximately 0.4 × 0.4 × 0.3 cm. The Deauville score decreased from 5 at baseline to 1 after treatment, meeting Lugano criteria for complete response. No clinically significant treatment-related adverse events were documented.
Lessons:
PB-DLBCL can closely mimic breast carcinoma on multimodal imaging. Suspicious breast imaging findings do not exclude lymphoma. Tissue diagnosis with adequate immunophenotypic and molecular evaluation is essential before definitive treatment planning to avoid misdiagnosis and unnecessary surgery.