Asian variant intravascular large B-cell lymphoma with highly suspected central nervous system involvement: A case report.

Background: Intravascular large B-cell lymphoma (IVLBCL) is a rare subtype of extranodal lymphoma. In particular, the Asian variant of IVLBCL is characterized by hemophagocytic lymphohistiocytosis along with bone marrow involvement. However, central nervous system (CNS) involvement is uncommon in this variant compared to the Western variant. Here, we report a case of typical Asian variant IVLBCL with highly suspected CNS involvement and discuss the nature of the disease and its genetic aberration.

Case Summary: A 67-year-old female patient complained of gradually worsening cognitive impairment. While hospitalized, she developed a high fever and showed marked bicytopenia. Intracranial imaging revealed a suspected leptomeningeal disease. Although no malignant cells were found in the cerebrospinal fluid (CSF), the protein and lactate dehydrogenase levels in CSF were increased. Bone marrow examination revealed an increased number of hemophagocytic histiocytes, and F-fluorodeoxyglucose (FDG) positron emission tomography with computerized tomography scan revealed increased FDG uptake in both adrenal glands, the liver, and the right ethmoid sinus. A tissue biopsy showed atypical large lymphoid cells with prominent nucleoli in the vessels, and the tumor cells were positive for CD20, BCL2, BCL6, and IRF4/MUM1. In addition, targeted sequencing identified , and mutations. Consequently, we diagnosed the patient with the Asian variant of IVLBCL with highly suspected CNS involvement.

Conclusion: Suspicion of IVLBCL and immediate diagnosis lead to timely treatment. Moreover, careful CNS examination at diagnosis is recommended.