Use of flow cytometry and cytology to differentiate breast implant-associated anaplastic large cell lymphoma from reactive seromas in Brazilian patients.

Introduction: The combination of cytology and multiparametric flow cytometry (MFC) may be useful in the diagnosis of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) and may be a practical way to differentiate lymphoma from benign and reactive seromas. Although the Brazilian breast implant market is the second largest in the world, with several manufacturers and the almost exclusive use of textured implants, the occurrence of BIA-ALCL in Brazil is underreported.

Methods: One hundred seventeen sequential collections of suspicious periprosthetic fluid (PF) from 105 Brazilian patients registered between March/2018 and March/2021 were evaluated by routine cytomorphology and flow cytometry. The combination of CD30, HLA-DR, and CD25 was used together with T and B lymphocyte and monocyte evaluation. The PF samples were divided into positive, acute reactive (neutrophilic exudate), or chronic reactive (macrophage or lymphocyte rich), and unavailable samples.

Results: Nine BIA-ALCL positive cases (7.7%) were identified, with typical morphology and increased FSC/SSC dispersion, bright expression of CD30, CD25 and HLA-DR, and absence or weakness of T-cell antigens (CD3, CD8, CD4, CD5, and CD7). Reactive samples were acute (n = 18, 15.4%) and chronic (n = 70, 59.8%). Twenty samples were excluded. The mean age of BIA-ALCL patients was 50 years (31-57 years) and 35 years in reactive patients (20-69 years).

Conclusion: Use of MFC with a comprehensive antibody panel consisting of CD30 in conjunction with CD25 and HLA-DR can discriminate anaplastic cells of BIA-ALCL from lymphoid or neutrophilic reactive cells and should be considered in the initial evaluation of seroma.