HHV8-unrelated primary effusion lymphoma: Two case reports and a review of literature

Although non-Hodgkin lymphoma (NHL), a cancer of the lymph nodes, may at times present as malignant pleural, pericardial, or peritoneal primary effusions, Primary Effusion Lymphoma (PEL) is a rare and aggressive subtype which lacks any distinguishable tumor masses. While it was originally thought that the lymphoma cells from PEL patients uniformly display the genome of human herpesvirus type 8/ Kaposi sarcoma-associated herpes virus (HHV8/KSHV), HHV8-unrelated PEL cases are being reported. Both PEL and HHV8-unrelated PEL-like lymphoma are associated with different pan B-cell markers as well as different comorbidities. Pan B cell markers, such as CD19, CD20, CD79A are usually absent on HHV8-associated PEL-like lymphoma cells but are almost always present on HHV8-negative lymphoma cells. The absence of pan B cell markers creates a differential treatment plan for PEL patients versus treatment for HHV8-unrelated PEL-like lymphoma patients. Specifically, anti-CD20 monoclonal antibodies (Anti-CD20 mAbs), such as rituximab, are effective treatments for HHV8-unrelated PELlike lymphoma patients whose lymphoma cells express CD20 markers. R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) has become a standard of care for these patients but is not a viable option for PEL-lymphoma patients without such pan B cell markers. The cases presented are two patients with HHV8-unrelated PEL-like lymphoma, displaying CD19, CD20, CD79A pan B cell markers. Both patients have similar comorbidities and are offered R-CHOP treatment.