Primary effusion lymphoma

The primary effusion lymphoma subtype is also known as 'body cavity-based' lymphoma and is considered one of three types of AIDS-related lymphoma.

What is primary effusion lymphoma?

Primary effusion lymphoma (PEL) is a very rare sub-subtype of extranodal diffuse large B-cell lymphoma. It is more frequently found to be affecting young and middle-aged men, much more often than women, and only occasionally is it found in elderly patients.

Medically, the term 'effusion' means that some body fluid—typically blood but any body fluid will do—has escaped into a body cavity or surrounding tissue (thus the alias of body cavity-based lymphoma). 'Effusion' can also refer to that escaped fluid.

Thus, in PEL, lymphoma develops within the effusion. It does not typically cause a mass or tumor.

Symptoms and diagnosis of primary effusion lymphoma

Patients diagnosed with Primary effusion lymphoma are almost always found to be positive for the HIV virus. Other viruses often found in patients with PEL, specifically within the cancerous lymphocytes, include both Epstein-Barr virus (EBV) and human herpes virus 8, better known as Kaposi-sarcoma associated herpes virus. That said, there is a distinction between EBV-positive and EBV-negative PEL, although it is unclear whether this factors into progression, prognosis or treatment considerations.

PEL patients are found to have one or more of the following effusion-related conditions:

• Pleural effusion (fluid that has escaped into the tissue that lines the lungs and chest cavity)
• Pericardial effusion (escape of fluid into the pericardial cavity, which is the sac and tissue surrounding the heart)
• Peritoneal effusion, better known as ascites (the escape of fluid into the cavity between the tissues lining the abdomen and its associated organs)

Prognosis of primary effusion lymphoma

Patients with primary effusion lymphoma have a poor prognosis, in large part because by the time of diagnosis not only is the lymphoma in advanced stage, the patients themselves are typically already highly immunocompromised. Death among these patients is generally caused by one of three diseases: the PEL, another cancer known as Kaposi's sarcoma, or an opportunistic infection characteristic of mortality in HIV/AIDS.

Researchers have noted that prognosis tends to be slightly better in (HIV positive) primary effusion lymphoma patients who are on antiretroviral therapy.

Sources

• Ferry JA. Extranodal Lymphoma. Archives of Pathology & Laboratory Medicine: April 2008, Vol. 132, No. 4, pp. 565-578.
• John P Doweiko MD. AIDS-related lymphomas: Primary effusion lymphoma.
• Fan W et al. Distinct Subsets of Primary Effusion Lymphoma Can Be Identified Based on Their Cellular Gene Expression Profile and Viral Association. Journal of Virology, January 2005, p. 1244-1251, Vol. 79, No. 2