title: Plasmablastic lymphoma of the stomach in an HIV-negative patient.
abstract: Plasmablastic lymphoma (PBL) is a rare B-cell neoplasm with an aggressive clinical behavior that predominantly occurs in the oral cavity of human immunodeficiency virus (HIV)-positive patients. However, it has recently been recognized that PBLs can also affect individuals without HIV infection, and suggested that these neoplasms show different clinicopathological characteristics between HIV-positive and -negative patients. Herein we describe a case of gastric PBL in a female HIV-negative patient. The tumor was composed of a diffuse and cohesive proliferation of large neoplastic cells, which resembled immunoblasts or plasmablasts with a starry sky appearance. Immunophenotypically, the neoplastic cells were diffusely positive for CD138, MUM1, IgM, and BOB-1, and negative for CK, LCA, CD3, CD20, CD79a, Pax5, kappa, lambda, CD30, ALK, S-100, HMB-45, MPO, and HHV-8. The MIB-1 index was nearly 100%. Epstein-Barr virus-encoded RNA in situ hybridization was negative. A monoclonal immunoglobulin heavy chain gene rearrangement was detected in polymerase chain reaction (PCR) and heteroduplex analyses. A combination of PCR-based analysis of immunoglobulin gene rearrangement and immunohistochemistry can be useful to substantiate the diagnosis by utilizing routine paraffin-embedded tissue sections, because PBL in the setting of extra-oral localization and immunocompetence is a diagnostic challenge, given its rarity, morphology, and absence of CD20 expression.
authors.affiliation: Department of Pathology, Aichi Medical University School of Medicine, Nagakute, Japan. mhashi@aichi-med-u.ac.jp
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Shingo
authors.initials: S
authors.lastname: Inaguma
authors.forename: Kenji
authors.initials: K
authors.lastname: Kasai
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kuwabara
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Noda
authors.forename: Masaya
authors.initials: M
authors.lastname: Hayakawa
authors.forename: Masahiko
authors.initials: M
authors.lastname: Fujino
authors.forename: Masafumi
authors.initials: M
authors.lastname: Ito
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikeda
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000378:metabolism; D049109:Cell Proliferation; D003520:Cyclophosphamide / Q000627:therapeutic use; D004317:Doxorubicin / Q000627:therapeutic use; D017809:Fatal Outcome; D005260:Female; D015321:Gene Rearrangement; D018023:HIV Seronegativity / Q000276:immunology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016400:Lymphoma, Large-Cell, Immunoblastic / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology*; D011241:Prednisone / Q000627:therapeutic use; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D014750:Vincristine / Q000627:therapeutic use
chemical_list: D014408:Biomarkers, Tumor; D007143:Immunoglobulin Heavy Chains; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011241:Prednisone