One important element of this study consists in the comparison of the BI-ALCL-associated cytokine milieu with that of the three different types of reactive effusions (i.e. acute, chronic and mixed), which revealed that high levels of IL-10, IL-13 and Eotaxin are able to differentiate BI-ALCL from all types of benign seromas. Here, IL10 is linked to anaplastic large cell lymphoma.