However, the effusion in this case was leaking fluid, and no evidence of malignancy was found by pathological immunohistochemistry; in previous case reports of PEL, rituximab was not effective because PEL does not express B-cell antigen.[7,8] In this case, the bone marrow pathology indicated CD20+, and rituximab had a better effect. The gene discussed is PPIB; the disease is primary effusion lymphoma.