A Rare Entity in Context: Breast Implant-Associated Anaplastic Large Cell Lymphoma Compared With Common Lymphoma Subtypes.

OBJECTIVE: Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a rare CD30-positive, anaplastic lymphoma kinase (ALK)-negative peripheral T-cell lymphoma now recognized as a distinct entity in the 5th edition World Health Organization Classification of haematolymphoid tumors. Its clinicopathologic profile, treatment patterns, and outcomes, relative to those of other primary breast lymphomas, have not been characterized in large population-based comparative studies. MATERIALS AND METHODS: Using the Surveillance, Epidemiology and End Results (SEER) database (2017-2022), we identified patients with primary breast lymphoma based on ICD-O-3 site (C50.0-C50.9) and morphology codes for BIA-ALCL (9715/3), diffuse large B-cell lymphoma (DLBCL, 9680/3), extranodal marginal zone [mucosa-associated lymphoid tissue (MALT)] lymphoma (9699/3), and Burkitt lymphoma (BL, 9687/3). Baseline characteristics, treatment, overall survival (OS), and cancer-specific survival (CSS) were compared between BIA-ALCL and other mammary lymphomas. RESULTS: Two hundred fifty-two patients with BIA-ALCL were identified and compared with 185,019 patients with other mammary lymphomas. Patients with BIA-ALCL were younger than those with DLBCL and MALT, but older than those with BL (mean age 62.8 years, p<0.001). BIA-ALCL demonstrated higher rates of surgical management and lower rates of radiotherapy compared with DLBCL and MALT. Chemotherapy utilization was intermediate among lymphoma subtypes. In unadjusted analyses, DLBCL was associated with worse OS [hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.03-2.08] and CSS (HR 1.84, 95% CI 1.21-2.79) relative to BIA-ALCL; BL was associated with worse CSS (HR 2.08, 95% CI 1.37-3.16); MALT lymphoma showed better CSS (HR 0.54, 95% CI 0.35-0.81). Multivariable analysis yielded HRs that were not statistically distinguishable from those for BIA-ALCL, but estimates were imprecise (adjusted OS for DLBCL: HR 1.53, 95% CI 0.21-10.90; for BL: HR 2.66, 95% CI 0.37-19.20); these wide CIs reflect sparse events within the BIA-ALCL cohort and preclude conclusions about survival equivalence. CONCLUSION: In this SEER-based analysis, breast-localized ALK-negative ALCL showed a distinct demographic and treatment profile characterized by surgical management, with favorable crude survival compared with that of DLBCL and BL. Early recognition and complete surgical excision remain central to the management of localized BIA-ALCL.