This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
All of the following statements regarding primary effusion lymphoma are true except - 
Select and explain. 
A. Also referred to as body cavity lymphoma, B. There is often an association with HHV-8, C. The proliferating cells are NK cells, D. Patients are commonly HIV positive
C: The proliferating cells are NK cells
Answer: C: The proliferating cells are NK cells 
Explanation: Two variants of immunoblastic lymphoma that are seen primarily in HIV-infected patients are primary effusion lymphoma (PEL) and its solid variant, plasmacyticlymphoma of the oral cavity. PEL, also referred to as body cavity lymphoma, presents with lymphomatous pleural, pericardial, and/ or peritoneal effusions in the absence of discrete nodal or extranodal masses. The tumor cells do not express surface markers for B cells or T cells and are felt to represent a preplasmacytic stage of differentiation. While both HHV-8 and EBV DNA sequences have been found in the genomes of the malignant cells from patients with body cavity lymphoma, KSHV is felt to be the driving force behind the oncogenesis (Harrison's Principles of internal medicine, 20 th edition, page 1566)