A left breast en-block capsulectomy was performed (Figure 4C, Video S2) with the diagnosis of BIA-ALCL; the implant capsule was focally infiltrated by atypical large cells positive for CD30 with a high Ki-67 labeling index; CD2 and CD4 were weakly positive; and stains for CD3, CD5, CD8, CD7, CD20, and CK were negative, as well as ALK. The gene discussed is CD4; the disease is anaplastic large cell lymphoma.