Plasmablastic lymphoma with unfavorable chromosomal abnormalities related to plasma cell myeloma: A borderline case between plasmablastic lymphoma and plasmablastic plasma cell myeloma

Plasmablastic lymphoma (PBL) is an aggressive subtype of DLBCL, first reported in HIV-infected patients1 and subsequently recognized in the WHO 2008 classification.2 PBL often arises in the oral cavity, but other sites include the nasal cavity, GI tract, skin, bone, and lungs.3-5 PBL mainly affects those with immunodeficiency,3-5 but can affect some immunocompetent individuals.6 Histologically, PBL presents as dense proliferation of immature cells like Burkitt’s lymphoma.2,5,7 The immunophenotype of PBL, however, resembles myeloma cells: CD38+, CD138+, cyIg+, MUM1+, CD45-, CD20-, and smIg-.3-5 EBV is mostly positive.3-5,7 A 53-year-old HIV-negative and immunocompetent woman was admitted because of chest pain and dyspnea. CT scanning revealed a large tumor in the right chest wall (Figure 1A), pleural effusion, para-aortic lymph node swelling, and a tumor in the sacral bone (Figure 1B and 1C, respectively). Laboratory findings are shown in Table 1. Serum IgG was 7,633 mg/dL, and revealed to be IgG-λ monoclonal protein. Many atypical plasma cell-like cells with CD38+, CD56+, CD138+, cyIgG+, and cyλ+ phenotype were observed in the pleural effusion (Figure 2). The karyotype was abnormal, with a complex involving chromosomes 1 and 3 (Table 1).8-10 Furthermore, FISH analysis demonstrated t(4;14).11 The chest tumor histologically exhibited dense proliferation of large immature cells (Figure 3A, B), and these cells were positive for CD138 and λ light chain (Figure 3C and 3D, respectively). A tentative diagnosis of multiple myeloma was made. She refused treatment with conventional anti-cancer agents. We therefore treated her with novel agents for myeloma, which were available in 2015 without any obvious response. Then, we performed radiotherapy for the chest tumor and other tumoral lesions. However, she died four months after admission. Histopathological re-examination of the chest tumor revealed it to be PBL. Immunostaining for myc was strongly positive as reported in PBL, and FISH split signal analyses for c-myc, but not for Bcl-2 or Bcl6, yielded split signals and amplification of this gene (Figure 3F). Serum virus genomes for EBV and HHV-8 were not detected by PCR. This patient appeared to have a borderline feature between plasmablastic plasma cell myeloma (PBPCM)12 because the tumor-involvement site was atypical for PBL3-5 and this patient carried multiple chromosomal abnormalities related with aggressive multiple myeloma.8-11 The genetic background of PBL has not yet fully understood5; therefore, accumulation of PBL cases and further molecular studies are required regarding clinical features and molecular profiles of PBPCM.