Primary effusion lymphoma (PEL) is a DLBCL in which neoplastic B cells that resemble immunoblasts, plasmablasts, or Reed–Sternberg cells infiltrate the pleural, pericardial, or peritoneal membranes that surround the lungs, heart, and abdominal organs, respectively. This infiltration leads to the seeping of fluid into the cavities which are encased by these membranes, i.e. it leads to pleural effusions, pericardial effusions, and abdominal ascites. Some cases of PEL also involve the gastrointestinal tract and lymph nodes. The disease occurs primarily in people who are immunosuppressed or test positive for HIV and are also latently infected with Kaposi's sarcoma-associated herpesvirus; PEL is an aggressive disease with an overall 1 year survival rate of ~30%.