What is characteristic of primary effusion lymphoma?

Primary effusion lymphoma is a rare type of non-Hodgkin lymphoma that typically presents in immunocompromised individuals, particularly those with HIV. A distinguishing feature of this lymphoma is that it arises in body cavities, such as the pleura, peritoneum, or pericardium, but does not form a discrete mass. Instead, it manifests primarily as an effusion, characterized by the accumulation of lymphomatous cells in the fluid within these cavities.

This absence of a mass, along with the presence of malignant effusions, is crucial for diagnosis and differentiation from other types of lymphoma that do present as solid masses. The clinical presentation predominantly involves fluid buildup rather than the more typical lymphadenopathy or solid tumor formation seen in other lymphomas, emphasizing the unique pathology of primary effusion lymphoma.

Additionally, while other options touch on aspects of lymphoma, they do not accurately encapsulate the primary feature of primary effusion lymphoma, which is specifically the occurrence of malignancy without a solid mass in body cavities. Thus, focusing on the effusion characteristic is essential for understanding this particular type of lymphoma.