A Rare Case of Plasmablastic Lymphoma with Gastric Involvement

Abstract

Plasmablastic lymphoma (PBL) is a relatively rare, but highly aggressive lymphoma commonly found in the setting of HIV disease.PBL is defined by the World Health Organization as a “diffuse proliferation of large neoplastic cells most of which resemble B-cell immunoblasts, but in which all tumor cells have a plasma cell immunophenotype.”Here we present a unique case of Ann Arbor Stage IV PBL with extranodal gastric involvement diagnosed in an immunocompetent male. An 80-year-old Hispanic male presented to the emergency department with nausea and epigastric pain for four days duration. The patient also endorsed progressive dysphagia to solids and liquids over the past several weeks prior to presentation. Significant findings on physical exam included a pale, well-nourished male with mild epigastric tenderness on light palpation. CT scan revealed diffuse thickening of the gastric wall with a 7.4cm x 6.5cm intraluminal infiltrating mass with luminal narrowing. An EGD was subsequently performed for better visualization and biopsy (Figure 1). Histopathologic studies ultimately identified the mass as malignant plasmablastic lymphoma with aberrant cytokeratin expression. HIV testing was negative but EBV IgG antibody testing was abnormally high. Immunophenotype analysis revealed that CD-138 was strongly positive, CD-20 was negative, CD-45 was weakly positive, and Ki-67 expression was greater than 90% (Figure 2). The patient was started on CHOP chemotherapy regimen.2659_A Figure 1. Large, 5cm, semi-circumferential, easily friable and fungating mass as observed from GE junction during EGD2659_B Figure 2. Histology and Immunophenotype Analysis. (A) High-power magnification showing atypical plasma cells. (B) CD-20 negative. (C) CD-138 positive. (D) Ki-67 Index > 90%.Recent meta-analysis has shown that the median age of diagnosis for HIV-negative PBL is 55 years. Although the pathogenesis of PBL remains incompletely understood, the association with EBV infection and the virus' role in prevention of apoptosis of B cells is well documented.EBV positivity and CD45 expression represent good prognostic indicators for this patient; on the other hand, Ann Arbor Stage IV classification and Ki-67 expression > 80% are typically associated with poor outcome. After the oral mucosa, the GI tract is the most common site of involvement for HIV-negative PBL cases. This case represents a rare phenotypic variant in which the BCL-6 transcription factor is positive, suggesting that perhaps this case is a hybrid of diffuse large B-cell lymphoma (DLBCL) and PBL. Despite the recent advances in the treatment for PBL, prognosis remains poor with the median overall survival of nine months and a 2-year overall survival rate of 10% for HIV-negative PBL.