Nonmalignant CD30+ Cells in Contralateral Peri-Implant Capsule of Patient With BIA-ALCL: A Premalignant Step?

CD30 lymphocyte activation antigen and phosphorylated STAT3 (pSTAT3) are consistent markers of tumor cells in breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). We present a case of BIA-ALCL in a breast implant capsule containing clustered tumor cells expressing CD30, pSTAT3, pSTAT6, interleukin 9, and granzyme B tumor cell biomarkers. Remarkably, the contralateral breast contained many scattered large, atypical CD30+ cells surrounded by inflammatory cells, raising a suspicion of bilateral BIA-ALCL, known to occur in some patients. To clarify the diagnosis, immunohistochemistry and multilabel immunofluorescence were performed. Unlike the tumor cells, the atypical CD30+ cells of the contralateral breast lacked pSTAT3, pSTAT6, interleukin 9, and granzyme B, eliminating a diagnosis of bilateral BIA-ALCL. This case highlights the importance of interpreting CD30 staining in the context of other tumor cell biomarkers and histopathology to avoid an incorrect diagnosis of BIA-ALCL. We believe the findings also suggest the possibility of CD30 expression as an early event in the multistep pathogenesis of BIA-ALCL.