Chih-Yi Liu ^1 2, Bo-Jung Chen ^3 4, Shih-Sung Chuang ⁵

Affiliations

1. Division of Pathology, Sijhih Cathay General Hospital, New Taipei City 221, Taiwan.
2. School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City 221, Taiwan.
3. Department of Pathology, Shuang Ho Hospital, Taipei Medical University, New Taipei City 221, Taiwan.
4. Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.
5. Department of Pathology, Chi-Mei Medical Center, Tainan 710, Taiwan.

ABSTRACT

Primary effusion lymphoma (PEL) is defined by the WHO classification as a large B-cell neoplasm without detectable tumor masses. It is universally associated with HHV8, with most cases occurring in the setting of immunodeficiency such as HIV infection, and a poor prognosis. Morphologically, the neoplastic cells range from immunoblastic, plasmablastic, to anaplastic; and phenotypically, most cases express plasma cell but not B-cell markers, i.e., plasmablastic. During the past decade, primary HHV8-negative effusion lymphoma has been reported. Such cases were considered in the WHO classification scheme as effusion-based lymphoma. We performed a systemic review of 167 HHV8-negative effusion lymphomas from the literature and found that only 42% were associated with a fluid overload state, and with low rates of HIV (6%) or EBV (21%) infection. Furthermore, most patients are old (or immunosenescent) with underlying medical conditions/comorbidities, most neoplasms are of B-cell phenotype, and the outcome is more favorable than that of HHV8-positive PEL. These distinctive findings supported our prior proposal of designating these HHV8-negative cases as type II PEL, in contrast to the classic or type I PEL as defined by the WHO. Furthermore, we propose an algorithmic approach for the diagnosis of PEL and its mimickers.

Keywords: EBV; HHV8; HIV; effusion-based lymphoma; primary effusion lymphoma.

< Review >Diagnostics (Basel). 2022 Mar 15;12(3):713. doi: 10.3390/diagnostics12030713.