Clinical and pathological features of lymphomas in the breast: a comprehensive multicentric study

Breast lymphomas, though rare, present a unique spectrum of clinical and pathological characteristics. This multicenter retrospective study evaluates 92 cases from four international institutions over a ten-year period to provide a comprehensive analysis of primary breast lymphomas (PBLs), secondary breast lymphomas (SBLs), and related subtypes, including breast implant-associated lymphomas (BIA-ALCL) and intra-mammary lymph node lymphomas. Primary breast lymphomas accounted for 46.7% of cases, with a predominance of diffuse large B-cell lymphoma (DLBCL). Secondary breast involvement, observed in 43.5% of cases, displayed a more diverse histological distribution, with follicular lymphoma being the most common subtype. Breast implant-associated lymphomas (BIA-ALCL) constituted 6.5% of cases, exclusively involving anaplastic large cell T-cell lymphoma, ALK-negative. The study highlights significant differences in patient demographics, clinical presentation, and survival outcomes. PBLs primarily affected older patients (mean age: 68.4 years) and were associated with longer lymphoma-specific survival compared to SBLs (76.12 vs. 59.45 months; p = 0.001). Notably, survival differences were evident within histological subtypes, emphasizing the impact of disease origin on prognosis. BIA-ALCL cases were distinct in clinical features and histology, with a younger mean age (47.5 years) and frequent association with unilateral effusion. This analysis underscores the necessity for precise diagnostic and therapeutic strategies tailored to the unique biology of breast lymphomas. Future research should aim to elucidate molecular mechanisms and optimize management protocols to improve patient outcomes.