Breast implant-associated anaplastic large cell lymphoma is an uncommon malignancy associated with textured breast implants, and since 2014 13 Danish cases have been identified. Early diagnosis is important to minimise morbidity. Most patients present with swelling of the breast due to seroma within the fibrous capsule, fewer with a tumour. The diagnosis is based on cytology/histology with finding of typical anaplastic large cells, positive for CD30 and negative for anaplastic lymphoma kinase. Staging includes bone marrow examination and PET-CT scan, and a minority need systemic treatment, as argued in this review.