[Diffuse large B-cell lymphoma with intravascular involvement of neoplastic CD5-positive cells]

Area of Science:

• Hematology
• Oncology
• Immunopathology

Background:

• Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma.
• CD20 is a common marker for B-cell lymphomas.
• CD5 expression is typically associated with chronic lymphocytic leukemia/small lymphocytic lymphoma and mantle cell lymphoma, but not commonly with DLBCL.

Observation:

• A 77-year-old male presented with fever and bone marrow findings of CD20-positive neoplastic cells.
• Initial symptoms improved with prednisolone.
• 11 months later, a liver mass revealed diffuse infiltration of CD20-positive neoplastic cells, diagnosed as DLBCL.

Findings:

• Neoplastic B cells within small blood vessels in the liver mass uniquely expressed CD5.
• This CD5 positivity was restricted to the neoplastic B cells in the liver vasculature.
• The patient succumbed to lymphoma three months post-diagnosis.

Implications:

• This case highlights the potential for unusual immunophenotypic variations in DLBCL.
• The CD5 expression on CD20+ neoplastic cells in vascular spaces may have implications for understanding lymphoma tropism and behavior.
• Further research into CD5 expression in DLBCL subtypes could reveal novel diagnostic or therapeutic strategies.