Anaplastic large T-cell lymphoma (BI-ALCL) is a rare primitive lymphoma found particularly in women with textured breast implant prostheses, which has been arousing interest in recent years due to its potentially high social impact. The difficult diagnosis together with the increasingly high number of prosthetic implants worldwide has led to a hypothesize of an underestimation of its real impact in prosthesis-bearing women. The clinical onset usually occurs with a cold seroma and disease confined to the prosthetic capsule while the more advanced stages may involve 1 or more lymph nodes or, rarely, distant metastases. Early diagnosis is essential as the disease has a favorable prognosis in over 90% of cases when detected in the early stages while it often has a poor prognosis in the advanced ones: despite this, the radiological signs of early disease are still non-specific. This report describes a case of BI-ALCL confined to the capsule which was studied using all diagnostic techniques in order to highlight its early radiological signs.