How B cell lymphoma caused PLE in our patient remains unclear but several potential mechanisms exist: (i) affection of intestinal lymph nodes resulting in lymphatic stasis, (ii) lymphatic hyperviscosity syndrome due to IgM paraprotein, (iii) epithelial deposition of the paraprotein, (iv) direct infiltration of the mucosa by lymphoma cells, (v) aberrant activity of the paraprotein, and (vi) paraneoplastic effect mediated by cytokines or by immune response to lymphoma. Here, CD40LG is linked to lymphoma.