<prompt> Answer this question truthfullyWhat is another name for primary effusion lymphoma and what type of lymphoma is it classified as?  <response>: <reason> Primary effusion lymphoma is also known as body cavity based lymphoma and is classified as a B-cell lymphoma. Primary effusion lymphoma is a rare and aggressive type of non-Hodgkin lymphoma that typically presents as fluid buildup in body cavities such as the pleural, peritoneal, or pericardial spaces. The lymphoma cells are characterized as B-cells, which are a type of white blood cell that normally produce antibodies to fight infections. In primary effusion lymphoma, the B-cells become malignant and grow uncontrollably, leading to the accumulation of fluid in the body cavities. The prognosis for primary effusion lymphoma is generally poor, and treatment options are limited. 