A case of CD45-negative diffuse large B-cell lymphoma in thyroid gland

Diffuse Large B Cell Lymphoma with Cutaneous and Gastrointestinal Involvement

Diffuse large B cell lymphoma (DLBCL) is the histological subtype of non-Hodgkin's lymphoma, representing approximately 30%. The most common primary extranodal sites of DLBCL are the gastrointestinal (GI) tract, the head and neck, and the skin/soft tissue. We report a case of DLBCL with cutaneous involvement presenting with skin nodules and GI manifestations such as obstructive jaundice and upper GI bleeding. Malignant cystic pancreatic tumor occupying the head and body with invasion to lower end of common bile duct and periampullary region causing biliary obstruction and mesenteric lymphadenopathy were found in abdominal computed tomography and endoscopic ultrasonography. There was also a large gastric ulcer (Forrest IIa) at the greater curvature of body of the stomach. Histopathological results of the skin and stomach were consistent with diffuse large B cell lymphoma; gastric biopsy being negative for leucocyte common antigen. The patient was considered to have disseminated DLBCL. The aim of the present case report was to present the clinical, radiological, and histological characteristics of the patient, which may aid physicians in diagnosing involvement of multiple extranodal sites in DLBCL.

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.

Immunohistochemistry in Primary B-cell Lymphoma of Tibia Masquerading as Chronic Osteomyelitis

The diagnosis between chronic osteomyelitis, Ewing sarcoma and lymphoma often is being confusing in many occasions. As the latter two conditions are malignant, early diagnosis and interventions are crucial. We present a 28 year old male with features of chronic osteomyelitis of right tibia 2 years back then changed through Ewing sarcoma to B-cell lymphoma in the histological diagnosis. This case report highlights the difficulties that arise in diagnosing primary bone lymphomas which may masquerade as chronic osteomyelitis and hence the need for immunohistochemistry in chronic recurrent osteomyelitis.

An unusual and challenging case of HIV-associated primary CNS Lymphoma with Hodgkin-like morphology and HIV encephalitis

HIV-associated primary CNS lymphomas are well-recognized, almost exclusively EBV-driven neoplasms with poor clinical prognosis. We report a challenging, atypical case of an HIV-associated lymphoproliferative disorder with unusual morphologic features reminiscent of Hodgkin Lymphoma, accompanied by HIV encephalitis. A 52-year-old male presented with acute seizures after seven months of progressive neurocognitive decline that was clinically diagnosed as progressive supranuclear palsy. Clinical work-up revealed HIV infection along with two ring-enhancing lesions in the brain on MRI, and negative CSF EBV testing. Subsequent biopsy showed well-demarcated hypercellular regions in the brain comprised of scattered Reed-Sternberg-like cells in a background of small to medium-sized lymphocytes exhibiting focal angiocentricity and geographic necrosis. The atypical cells were positive for CD20, EBV, and CD79a, and negative for CD45, GFAP, CD15, CD30, and p24. These cells were admixed with numerous CD68-positive cells. The adjacent brain showed classic features of HIV encephalitis with perivascular, CD68 and p24-positive multinucleated giant cells. This case illustrates several diagnostic pitfalls in the work-up of HIV-associated brain lesions, as well as reporting a unique histomorphology for an HIV-related primary CNS lymphoproliferative disorder.

Flow cytometry CD45-negative B-NHL: a case report of a diffuse large B-cell lymphoma without extranodal involvement

BACKGROUND

The loss of CD45, the leukocyte-common antigen, has been described in rare cases of large B-cell lymphoma (LBCL) subtypes with extranodal involvement by immunohistochemical methods. Here we report a case of a patient with LBCL, with no extranodal lesions, which is CD45 negative by flow cytometry (FC) immunophenotyping.

METHODS

Immunophenotyping and DNA content analysis was performed by multiparametric FC on lymph node and bone marrow aspirate obtained from a 65 year old male patient.

RESULTS

Malignant B-lymphocytes were CD5-, CD10+/++, CD11c-, CD19+, CD20+/++, CD23-, CD34-, CD38-/+, CD45-, CD79b++/+++, BCL2 overexpressed, FMC7++, IgM++/+++, TdT- with Lambda light chain restriction. This pathological cellular population showed near-diploid DNA content, with a high proliferate rate.

CONCLUSIONS

To our knowledge, we describe the first case of a CD19+ B-cell non-Hodgkin lymphoma without expression of CD45 detected by FC, and the first case without extranodal involvement presentation. This case is reported not only because it is a rare one but also to raise awareness of FC users of its correct diagnosis.