Late onset of fluid collection surrounding breast implants may represent a serious issue when considering the possibility of breast implant-associated anaplastic large cell lymphoma, a newly recognized type of T-cell malignancy. However, many other factors, including trauma and infections, may be implicated in the formation of non-neoplastic periprosthetic delayed effusions. An appropriate management of late seromas, consisting of ultrasound-guided fluid drainage, cultures, cytology, and immunocytochemical and T-cell clonality studies, should be performed to achieve a correct and prompt diagnosis of breast implant-associated anaplastic large cell lymphoma. Criticisms in the diagnosis of late peri-implant effusions are here discussed in detail.