An unusual case of Epstein-Barr virus-positive large B-cell lymphoma lacking various B-cell markers

Primary Nodal Unclassifiable CD20 Negative Diffuse Large B-cell Lymphoma With Dual IgK and TCR Gene Rearrangement: A Diagnostic Challenge

Non-Hodgkin lymphomas are most frequently classified based on the lineage marker expression. However, lymphomas with aberrant marker expression as well as monoclonal IgH/IgΚ and TCR gene rearrangements may co-exist which can be misleading and confusing. Primary CD20 negative diffuse large B-cell lymphomas (DLBCL) represent a rare entity, and they account for 1% to 3% of cases. However, some CD20 negative DLBCLs could not be classified into known variants, creating both diagnostic and therapeutic dilemma's. Primary CD20 negative DLBCL are more likely to have a non-germinal centre subtype, a higher proliferation index, more frequent extra-nodal involvement, a poorer response, and poorer prognosis to conventional treatment compared to CD20 positive DLBCL. A 66- year-old postmenopausal lady, presented with palpable, bilateral neck lymphadenopathy and difficulty swallowing. She also had left leg lymphoedema, poor appetited, fatigue and weight loss. Her symptoms lasted approximately 1 month. After histological, immunohistochemical and clonality analysis of the lymph node the patient was diagnosed with primary nodal CD20 and PAX-5 negative DLBCL with dual immunoglobulin light-chain kappa (IgK) and T-cell receptor (TCR) gene rearrangement. This unusual and unique case presented a diagnostic challenge because it was CD20 and PAX-5 negative, had dual IgK and TCR gene rearrangement and, it could not be classified within the known and well established CD20 negative DLBCL variants. Describing such cases emphasises the fact that lymphomas unclassifiable within known variants of CD20 negative DLBCL do exist and that range and heterogeneity of CD20 negative DLBCL continues to evolve, and pathologist should be aware of these uncommon, atypical mature B-cell neoplasms.

Case report of primary CD20 negative diffuse large B-cell lymphoma

Few groups of aggressive non-Hodgkin's lymphomas (NHL) that are refractory to standard chemotherapy are rarely reported. Primary CD20 negative diffuse large B cell lymphoma (DLBCL) without human immunodeficiency virus infection is an uncommon presentation and this case report is challenging in terms of diagnosis and treatment as well.

Nodal EBV-positive polymorphic B cell lymphoproliferative disorder with plasma cell differentiation: clinicopathological analysis of five cases

Plasma cell differentiation (PCD) is frequently observed in some entities of non-Hodgkin B cell lymphoma, including both low-grade and high-grade lymphomas. However, except for plasmablastic lymphoma and primary effusion lymphoma, EBV⁺ B cell lymphoproliferative disorder (LPD) with PCD has not been well addressed due to its rarity. We clinicopathologically examined five cases of nodal EBV⁺ polymorphic B cell LPD with PCD (PBLPD-PCD) initially diagnosed as polymorphic EBV⁺ diffuse large B cell lymphoma, not otherwise specified (DLBCL-NOS) with PCD (n = 3) and methotrexate-associated B cell LPD (MTX-associated B-LPD) (n = 2). One case had a concomitant brain lesion which was clinically diagnosed as EBV-related encephalitis. This patient received therapy with vidarabine, and both the brain lesion and the nodal EBV⁺ PBLPD-PCD lesions disappeared. Another case was characterized by Mott cell differentiation. This case was the first reported case of EBV⁺ B cell lymphoma or LPD with Mott cell differentiation. The two cases of MTX-associated B cell LPD which arose in patients with rheumatoid arthritis spontaneously regressed after MTX cessation. TCRγ and IGH PCR analysis was performed in four cases. Two cases had TCRγ rearrangements, but no IGH rearrangements. The other two cases had no rearrangements in these genes. We concluded that nodal EBV⁺ PBLPD-PCD is rare, with heterogeneous characteristics. PCR analysis revealed that nodal EBV⁺ PBLPD-PCD may have only TCR clonality and no IGH clonality. Considering the partial or complete loss of CD20 expression on the tumor cells, this result may be confusing for accurate diagnosis of EBV⁺ PBLPD-PCD, and pathologists need to be aware of this phenomenon to avoid misdiagnosis.

Epstein-Barr Virus–Positive CD20- and CD45-Negative Diffuse Large B-Cell Lymphoma: A Diagnostic Challenge

Diffuse large B-cell lymphoma (DLBCL) is characterized by medium- to large-sized neoplastic cells that express a wide range of B-cell markers including CD19, CD20, CD22, and CD79a. Also, as this is a hematopoietic malignancy, there is expression of the leukocyte common antigen CD45. Lack of CD20 expression occurs in a specific rare heterogeneous subgroup of DLBCL including primary effusion lymphoma, plasmablastic lymphoma, ALK-positive large B-cell lymphoma, and large B-cell lymphoma arising in HHV8+ multicentric Castleman disease. In this article, we report a rare case of CD20- and CD45-negative Epstein-Barr virus–positive DLBCL in which the entities listed above were ruled out, thereby posing a significant diagnostic challenge. Arriving at the correct diagnosis of Epstein-Barr virus–positive DLBCL was supported by immunoreactivity for the B-cell transcription factor Oct-2 and the pan-B cell marker CD79a.

De Novo Unclassifiable CD20-Negative Diffuse Large B-Cell Lymphoma: A Diagnostic and Therapeutic Challenge

CD20-negative diffuse large B-cell lymphomas (DLBCLs) constitute a rare and heterogeneous group of aggressive lymphomas. Known well-documented variants include plasmablastic lymphomas, primary effusion lymphomas, anaplastic kinase-positive large B-cell lymphomas, and large B-cell lymphomas arising in human herpesvirus 8 (HHV8)-associated multicentric Castleman disease. They impose diagnostic challenges for pathologists and therapeutic confrontations for clinicians. CD20 loss in B-cell lymphomas is a well-known phenomenon after rituximab therapy. De novo loss of CD20 has been reported in human immunodeficiency virus (HIV)-positive patients. Rare cases of primary CD20-negative DLBCLs that did not meet the criteria of the well-established subtypes of CD20-negative DLBCLs have been reported. This might expand the spectrum of unclassifiable CD20-negative DLBCLs with aberrant genetic and immunophenotypes. This imposes further diagnostic and therapeutic challenges. We report a case of a primary CD20-negative DLBCL in an HIV-infected female patient with an Epstein Barr virus (EBV) coinfection, who presented with generalized lymphadenopathy and fever. The nodal neoplastic immunoblasts were positive for LCA, PAX5, CD30, OCT2, BOB1, MUM1, CD79a, and CD19. Ki67 proliferation index was 100%. They were negative for CD20, CD3, ALK, EMA, CD138, CD38, EBV, and HHV8. Our case did not meet the criteria of the known variants of CD20-negative DLBCLs. The aim of this study is to highlight the diagnostic challenges associated with CD20-negative DLBCLs. De novo unclassifiable CD20-negative DLBCLs might raise an insight into the complex genetic mechanisms of CD20 concealment with variable immunoprofiles and resistance to conventional chemotherapies.