Plasmablastic lymphoma: oral vs extraoral

Background Originally thought to be exclusive to the oral cavity in human immunodeficiency virus (HIV)-infected persons, plasmablastic lymphoma (PBL) is increasingly described extraorally, and in non-HIV-infected patients. Demographic data are often dependent on case reports, case series, and systemic reviews. Objective This is an epidemiological, morphological, and immunological comparison of oral and extraoral PBLs in a high HIV endemic setting. Methods This retrospective study of extraoral and oral PBLs diagnosed over a 5-year period analyzed patients’ age, sex, HIV status, and tumor site. Histologic diagnosis was confirmed and tumors were assessed immunohistochemically with CD45 (LCA), CD20, CD79a, PAX5, CD138, MUM1, BLIMP1, VS38c, Ki-67, BCL6, CD10, and HHV8 using the manufacturers’ protocols. The presence of Epstein-Barr virus (EBV) was assessed by chromogenic in situ hybridization. Ethics clearance: M10750. Results There were 46 extraoral and 54 oral PBLs. Patient age ranged from 9 to 59 years (extraoral) and from 22 to 78 years (oral). In known HIV cases, 95% of extraoral and 97% of oral cases were HIV-positive. None had systemic disease at presentation. The male:female ratio was 1.4:1 for extraoral and 2.7:1 for oral PBLs. The favored extraoral and oral sites were the anus (28%) and maxilla (29%). Immunohistochemical profiles recapitulated that previously reported, except for CD45 expression, which was higher (85.7% extraoral, 97% oral). EBV was positive by in situ hybridization in 96% of PBLs, 93% of extraoral PBLs, and all oral PBLs. Conclusions Extraoral and oral PBLs are identical in sex and age distribution, HIV status, morphological appearance, immunophenotypic profile, and EBV association. PBL should be regarded as the same tumor irrespective of oral or extraoral site of origin.