CD19 and primary effusion lymphoma: The neoplastic cells in PEL lack surface expression of B-cell markers, such as CD19, CD20, CD79a, and immunoglobulin, they express plasma cell-related markers, such as CD30, CD38, CD45, and CD138, but they also exhibit clonal rearrangement and somatic hypermutation of immunoglobulin genes, suggesting that they originate from post-germinal center B-cells [1,5,6,7].