label: Primary Effusion Lymphoma
label_lc: primary effusion lymphoma
description: A large B-cell lymphoma usually presenting as a serous effusion without detectable tumor masses. It is universally associated with human herpes virus 8 (HHV8), also called Kaposi sarcoma-associated herpesvirus.  It mostly occurs in the setting of immunodeficiency. The most common sites of involvement are the pleural, pericardial, and peritoneal cavities. Rare HHV8-positive lymphomas indistinguishable from primary effusion lymphomas (PEL) present as solid tumor masses, and have been termed extracavitary PEL. The prognosis is extremely unfavorable. (WHO 2017)