AIDS-related extranodal non-Hodgkin's lymphomas with plasma cell differentiation.

To the Editor: centrally or eccentrically placed nucleus with a single prominent nucleolus or several nucleoli was observed in all instances. Single-cell necroses were numerous. The immunophenotype of the Although the spectrum of acquired immunodeficiency syndrome BCBL cases was CD20, CD45, epithelial membrane antigen (AIDS)related non-Hodgkin’s lymphomas (AIDS-NHLs) tradition(EMA), VS38c, CD138/B-B4 (Fig 1A), whereas PBLs were ally included systemic NHLs and primary central nervous system CD20, CD45, EMA, VS38c, CD138/B-B4 (Fig 1B). The lymphomas (PCNSLs), novel AIDS-NHL entities are being continu‘‘intermediate’’ lymphomas displayed a weak cytoplasmic posiously identified. Recently, the spectrum of systemic NHLs has been tivity for CD20 and CD45 in a variable proportion of the tumor expanded to include an atypical variant mainly made up of blastic cells. The VS38c, CD138/B-B4, and EMA staining was also seen cells exhibiting features ‘‘intermediate’’ between small noncleaved in the ‘‘intermediate’’ lymphoma cases, but it was usually concell lymphoma (SNCCL-Burkitt’s lymphoma) with plasmablastic fined to a minority of cells. Only in one case was the proportion differentiation and diffuse large cell lymphoma (DLCL) of the imof the VS38c and CD138/B-B4 cells higher than 20% (Fig munoblastic (IBL)-plasmacytoid subtype. A novel type of AIDS1C). The staining with the CD79a monoclonal antibody (MoAb) NHL, termed HHV-8 body cavity-based lymphoma (BCBL), has was restricted to a fraction of ‘‘intermediate’’ lymphomas and also been described in North America and Europe during the last 2 PBLs, whereas CD43 (leukosialin) positivity was virtually reyears. Very recently, a new lymphoma entity associated with the stricted to the ‘‘intermediate’’ lymphomas and BCBLs. The human immunodeficiency virus (HIV) infection has been identified majority of the reported lymphomas were Epstein-Barr virus among DLCLs of the oral cavity. These lymphomas have been (EBV)-positive, irrespective of the tumor types, whereas HHVdesignated as ‘‘plasmablastic lymphomas’’ (PBL) in accordance 8 positivity, as assessed by polymerase chain reaction (PCR) and with their plasmablastic morphology and immunohistologic feain situ hybridization (ISH), was selectively detected in BCBL, tures. as expected. The fact that plasma cell differentiation is a common feature Although not yet formally recognized as individual entities by shared by BCBL, PBL, and ‘‘intermediate’’ lymphomas prompts classifications of NHL of the immunocompetent hosts, ‘‘intermethe question of whether these AIDS-NHLs are mutually related. diate’’ lymphomas and HHV8 BCBLs have been officially inIn a clinical perspective, although BCBL and PBL associate with cluded in the recent classification of AIDS-related lymphoprolidistinctive clinical features that greatly contribute to their diagnosis, ferative disorders adopted by the IARC/WHO Working Group on ie, origin in the body cavities or the oral cavities, respectively, a AIDS and Tumours. The present study corroborates previously biologic/immunophenotypic differentiation between these two reported evidence indicating that PBL should be singled out as AIDS-NHLs and versus ‘‘intermediate’’ lymphomas may be helpful an individual pathologic entity. Among extranodal AIDS-NHLs in refining the classification of these novel lymphoma entities. To with plasma cell differentiation, AIDS-PBLs share several feaaddress these issues, we analyzed 16 samples from 5 PBLs of the tures with AIDS-related ‘‘intermediate’’ lymphomas and BCBLs; oral cavity, 6 ‘‘intermediate’’ lymphomas, and 5 HHV-8 BCBLs. however, PBL may be differentiated based on an infrequent and They represent 2.6%, 3.1%, and 2.6%, respectively of a total of 191 weak expression of CD45 (positive in ‘‘intermediate’’ lymphoma AIDS-NHLs consecutively seen at the same institution between 1984 and BCBL), lack of HHV-8 infection (positive in BCBL), and and 1997. constant reaction with the new plasma cell reacting antibodies As shown in Table 1, all the reported lymphomas were extranodal. A variable proportion of large neoplastic cells having a VS38c and CD138/B-B4.