title: Kaposi sarcoma herpesvirus/human herpesvirus-8-negative effusion-based lymphoma: report of 3 cases and review of the literature.
abstract: BACKGROUND
  Primary effusion lymphoma (PEL) is a rare subtype of large B-cell lymphoma that arises in body cavities without detectable tumor masses. PEL is universally associated with Kaposi sarcoma herpesvirus (KSHV)/human herpesvirus-8 (HHV8). Despite overlapping features, KSHV/HHV8-negative effusion-based lymphoma is a distinct entity from PEL. To date, 52 cases have been reported. The authors report 3 additional cases received in their laboratory from 2007 to 2012.
  
  
  METHODS
  Clinical data, cytomorphologic features, and immunophenotypic features of the 3 cases were described and compared with those reported in the literature.
  
  
  RESULTS
  The cells in HHV8-negative effusion lymphoma commonly revealed large cell, immunoblastic morphology and B-cell immunophenotype. The 3 cases demonstrated cytomorphologic and immunophenotypic variability. Cytomorphologically, 1 case contained large, highly atypical cells with a moderate amount of cytoplasm, round nucleus, coarsely granular chromatin, and a single macronucleolus. The other 2 cases had medium to large atypical cells with high nuclear-to-cytoplasmic ratios, slightly irregular to cleaved nuclei, and multiple conspicuous nucleoli. One case had a null phenotype with aberrant cytokeratin expression. B-cell phenotype was established by clonal immunoglobulin heavy-chain rearrangement using polymerase chain reaction, whereas the other 2 cases demonstrated a B-cell phenotype by flow cytometry and immunohistochemical staining. All 3 cases were negative for both HHV8 and Epstein-Barr virus.
  
  
  CONCLUSIONS
  HHV8-negative effusion lymphoma exhibits clinical, cytomorphologic, and immunophenotypic variability. Cases with a null-phenotype can be particularly challenging. When effusion lymphoma is suspected, ancillary tests are helpful. Moreover, HHV8 detection is critical in differentiating PEL and HHV8-negative effusion lymphoma, because they have overlapping features yet different prognoses.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors.forename: Jingnan
authors.initials: J
authors.lastname: Xiao
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Selvaggi
authors.forename: Catherine P
authors.initials: CP
authors.lastname: Leith
authors.forename: Sean A
authors.initials: SA
authors.lastname: Fitzgerald
authors.forename: Jimmie
authors.initials: J
authors.lastname: Stewart
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019288:Herpesvirus 8, Human; D006801:Humans; D016130:Immunophenotyping / Q000379:methods; D054685:Lymphoma, Primary Effusion / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000473:pathology*; D035583:Rare Diseases / Q000473:pathology*; D012514:Sarcoma, Kaposi / Q000473:pathology* / Q000821:virology
keywords: Kaposi sarcoma herpesvirus/human herpesvirus-8; effusion lymphoma; pericardial effusion; pleural effusion; primary effusion lymphoma