Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a new provisional category in the 2016 World Health Organization (WHO) classification of lymphoid neoplasms, and its incidence is rising owing to increasing recognition of this complication of breast implant insertion. At a median of 10 years after implant insertion, the typical presenting features are sudden-onset breast swelling secondary to peri-implant effusion and less frequently mass-forming disease. Histologic features comprise pleomorphic cells expressing CD30 and negative anaplastic lymphoma kinase (ALK) receptor, similar to systemic and cutaneous ALK-negative anaplastic large cell lymphoma (ALCL). The effusion-only subtype is generally indolent and curable with surgery, unlike the more aggressive mass-forming disease, for which systemic therapy is advocated. High clinical suspicion and pertinent use of radiologic and pathology modalities are essential for timely and accurate diagnosis of BIA-ALCL. Contemporary imaging techniques including US, mammography, breast MRI, CT, and PET/CT are routinely used in breast disease and lymphomas; however, the unique behavior of BIA-ALCL presents significant diagnostic and radiologic interpretative challenges, with numerous nuanced imaging features being pertinent, and current lymphoma staging and response guidelines are not easily applicable to BIA-ALCL. The authors evaluate available evidence in this evolving field; detail key indications, strengths, and limitations of the panoply of radiologic techniques for BIA-ALCL; and propose multiparametric imaging paradigms for management of the peri-implant effusion and mass-forming or advanced disease subtypes, with the goal of accurate optimal patient care. The authors also predict a future model of multimodal assessment using novel imaging and molecular techniques and define key research directions. ©RSNA, 2020.