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6 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
A rare lymphoma that grows as fluid rather than as a lump: it fills the space around the lungs, the heart or the bowel without forming a mass. It is caused by Kaposi sarcoma herpesvirus and arises mostly in people with advanced HIV infection, and it is diagnosed by sending the fluid itself for testing.
What it is. A large B-cell lymphoma driven by Kaposi sarcoma herpesvirus, also called human herpesvirus 8, the same virus that causes Kaposi sarcoma. The lymphoma cells float free in a body cavity and produce fluid: a pleural effusion around the lung, a pericardial effusion around the heart, or ascites in the abdomen. Classically there is no tumour mass at all, which is why the diagnosis is made on the fluid.
How it differs from the lymphomas around it. WHO-HAEM5 groups it in a family of conditions caused by the same virus: multicentric Castleman disease, germinotropic lymphoproliferative disorder, primary effusion lymphoma, its extracavitary form, and KSHV/HHV8-positive diffuse large B-cell lymphoma. The classification acknowledges that the boundaries between them are not clean, that individual patients overlap, and that difficult cases should be settled in a multidisciplinary meeting rather than by rule. In particular, telling a lymph node-based extracavitary primary effusion lymphoma from a KSHV/HHV8-positive diffuse large B-cell lymphoma can be arbitrary; the International Consensus Classification prefers the latter diagnosis where Epstein-Barr virus is negative and the tumour expresses IgM lambda.
| Setting | Approach | Guideline |
|---|---|---|
| Making the diagnosis on the fluid | The effusion is drained and sent, fresh, for cytology, flow cytometry and immunohistochemistry. The diagnosis requires the Kaposi sarcoma herpesvirus latency-associated nuclear antigen in the tumour nuclei. A cavity lymphoma without the virus is a different disease, recognised separately in 2022, that arises in fluid overload from heart failure, kidney failure or cirrhosis and behaves better. HIV testing is part of the work-up in every case. | not mapped |
| Treatment | Combination chemotherapy, with antiretroviral therapy started or optimised at the same time where there is HIV, because controlling the HIV is part of controlling the lymphoma. Anti-CD20 antibodies have no role: the cells do not carry CD20. There has never been a randomised trial in this entity and the regimens come from series and from the HIV-associated lymphoma literature; they sit in the treatment layer of this family and on the HIV-associated lymphoma page. Entry into a trial is a reasonable first choice rather than a last resort. | not mapped |