Primary effusion lymphoma: A liquid phase lymphoma of fluid-filled body cavities

This chapter discusses primary effusion lymphoma (PEL). PEL is a B-cell neoplasm characterized by infection of the tumor clone by human herpesvirus type-8/Kaposi's sarcoma-associated herpesvirus (HHV-8/KSHV), and by liquid growth in fluid-filled body spaces. During its entire clinical course, the lymphoma tends to remain localized to the serous body cavities with no formation of solid tumor masses. PEL is composed of postgerminal center B cells, which bridge immunoblastic and anaplastic features, and typically display a non-B, non-T phenotype consistent with late stages of B-cell differentiation. HHV-8/KSHV is thought to play a major role in PEL pathogenesis via expression of several viral latent genes, which have the potential to affect B-cell growth. Other factors involved in PEL pathogenesis include deregulation of cytokine and growth factor autocrine loops, molecular alterations of the tumor DNA, cell cycle abnormalities, stimulation and selection by antigen, and infection by Epstein–Barr virus, which occurs in 70% of PEL cases.