By Jason Wasserman MD PhD FRCPC
September 19, 2023
EBV-positive DLBCL commonly involves the lungs, digestive tract, skin, bone marrow, and lymph nodes.
Symptoms of EBV-positive DLBCL include fever, weight loss, and fatigue. Patients with lymph node involvement may notice a lump or swelling on the neck, under the arms, or around the groin.
What causes EBV-positive DLBCL is currently unknown. Although the tumour cells are infected by EBV, infection alone is not enough to cause the disease. Other factors, such as decreased immune system activity, are believed to also play a role in the development of this disease.
The diagnosis can only be made after tissue from the tumour is examined under a microscope by a pathologist.
When examined under the microscope, EBV-positive DLBCL is made up of large abnormal-looking B cells. The tumour cells commonly spread and efface (destroy) the surrounding normal tissue. Large areas of “geographic” necrosis (cell death) are commonly seen inside the tumour.
In some cases, the abnormal B cells will resemble the tumour cells normally found in a type of cancer called Hodgkin lymphoma. These cells are often described as being Hodgkin/Reed-Sternberg-like (HRS-like). Despite the presence of these HRS-like cells, EBV-positive DLBCL is not a type of Hodgkin lymphoma.
The tumour is described as polymorphic when the abnormal B cells are surrounded by other types of immune cells such as lymphocytes, plasma cells, and histiocytes. These cells are described as reactive because they are noncancerous cells that are responding to the presence of a tumour. The tumour is described as monomorphic when the abnormal B cells are arranged in large groups of cells with very few noncancerous immune cells in the background.
Immunohistochemistry (IHC) and in situ hybridization (ISH) are often performed to confirm the diagnosis. IHC is important because it allows pathologists to determine the types of cells present in the tumour. When IHC is performed the tumour cells in EBV-positive DLBCL will be positive or reactive for B cell markers such as CD19, CD20, CD79a, and PAX-5. The tumour cells may also be positive for CD30. The tumour cells will be negative or nonreactive for T cell markers such as CD3 and CD5.
ISH is performed to confirm the presence of EBV inside the tumour cells. This test allows pathologists to look for a marker called EBER which is produced by cells infected by EBV. When ISH is performed, the tumour cells in EBV-positive DLBCL are always positive or reactive for EBER.