Case Report: From Kaposi's sarcoma to primary effusive lymphoma.

Primary effusion lymphoma (PEL) is a rare B-cell lymphoma with an extremely poor prognosis that is associated with long-term persistent latent infection with Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV). However, studies on the correlation between KSHV genotype and PEL development in elderly patients are still lacking. We present the first global case of non-HIV, non-effusive, difficult-to-diagnose PEL with disseminated Kaposi's sarcoma (KS) in an elderly patient of Bouyei nationality, dynamically demonstrating that KSHV and EBV co-infection promote tumorigenesis. Phylogenetic analysis based on the Open Coding Framework (ORF)-K1 gene indicated that five samples from the patient's blood (mtl A), saliva (mtl B), descending colon (mtl C), skin (mtl D), and gastric mucosa (mtl E) may belong to a new subtype, Cnew. KSHV genotypes appear to show a pattern of traceability consistent with the human Y-chromosome DNA haplogroup tree.