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Case Presentation - Winter, 2011

Primary Effusion Lymphoma

Note:The diagnosis and analysis for this case study were provided by an independent physician. All conclusions and opinions are those of the physician and not Hologic, Inc.

Patient Age and History: 88 y/o male

Specimen type: Pleural fluid

Cytologic diagnosis: Primary Effusion Lymphoma

Case provided by: The laboratory that provided this case would prefer to remain anonymous.

General
Primary Effusion Lymphoma (PEL) is an aggressive type of Non-Hodgkin's lymphoma. Primary Effusion Lymphoma is rare, representing less than 2% of Non-Hodgkin's Lymphoma cases. PEL is caused by Kaposi's sarcoma‚Äďassociated herpes virus, or HHV-8. PEL most commonly arises in patients who are immunosuppressed and are infected with HIV. The Epstein-Barr virus is also found in 90% of these lymphoma cells. The World Health Organization (WHO) first recognized Primary Effusion Lymphoma as a distinct entity in their classification of neoplastic diseases of the hematopoietic and lymphoid tissues in 2001.

Clinical Presentation
Primary Effusion Lymphoma is also known as Body Cavity Lymphoma. It can arise in the pericardial, pleural, or peritoneal cavities in the body, usually involves only one body cavity and most often occurs in the pleural cavity. While PEL lacks obvious lymphoma tumor masses, the lymphoma cells cause a malignant effusion in the body cavity spaces resulting in shortness of breath, gastrointestinal organ dysfunction or chest pain. Swollen lymph nodes are generally absent in this type of lymphoma.

Almost all patients with primary effusion lymphoma are HIV-positive with a decreased CD4 T-cell count at diagnosis. Many patients also have pre-existing Kaposi's sarcoma. Cases of PEL have also been reported in patients who were immunosuppressed for other reasons, such as post-organ transplantation.

Cytology and Diagnosis
Since obvious lymphoma masses are absent, the diagnosis of PEL is made on a cytological preparation of the effusion. The malignant effusion is analyzed employing immunophenotypic, molecular, morphologic and virologic criteria. Small numbers of malignant cells may also adhere to the mesothelial-lined surfaces of the involved body cavity. Underlying invasion of these surfaces by lymphoma cells occasionally occurs. Morphologically, the malignant cells are large, and possess round or irregular nuclei with prominent nucleoli. Cytoplasm is variable and occasionally vacuolated. Malignant cells can exhibit a variety of appearances. They can be immunoblastic displaying central conspicuous nucleoli within a round nuclei, plasmablastic with abundant cytoplasm with occasional perinuclear hofs and eccentric nuclei or large anaplastic cells with pleomorphic nuclei.

Lymphoma cells must be positive for infection by Kaposi's sarcoma-associated herpesvirus, HHV-8, to be diagnostic for PEL. HHV-8 can be detected in the neoplastic cells by immunohistochemical methods utilizing the HHV8 LNA-1 latent protein antibody, or by the molecular techniques of Southern blot analysis or PCR amplification.

PEL is a large cell lymphoma and is considered a B-cell lymphoma through molecular studies. It frequently expresses plasma cell markers CD30, CD38, CD138, and EMA. PEL is usually of null phenotype by immunohistochemistry.

Treatment and Prognosis
Patients with a diagnosis of PEL receive CT scans of the pelvis, abdomen and chest as a part of initial staging. Serum chemistries and complete blood counts are also performed. Staging studies give a baseline estimation of the extent of disease and help assess treatment response.

Due to the rarity of PEL, there are no prospective, randomized clinical trials to guide treatment decisions and no recommended standard treatment. The treatment data available is based upon published case reports. Treatment for PEL has been modeled after diffuse large B-cell lymphoma, an aggressive type of Non-Hodgkins lymphoma. CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy regimens and, if HIV positive, antiretroviral therapies are used. These therapies have a reported response rate of 40 to 50%.

PEL is considered to be an advanced, stage IV disease. Prognosis is poor with a median survival of 6 months. The one year overall survival rate is approximately 39%. Patients frequently die from HIV-related complications, opportunistic infections or progression of lymphoma.

References:
  1. Chen Y, et al. Primary Effusion Lymphoma. The Oncologist, Vol. 12, 569-576, May 2007.
  2. http://www.knowcancer.com/oncology/primary-effusion-lymphoma/
  3. Brimo F, Popradi G, Michel RP, Auger M. Primary effusion lymphoma involving three body cavities. CytoJournal [serial online] 2009 [cited 2010 Oct 5];6:21. Available from: http://www.cytojournal.com/text.asp?2009/6/1/21/56361