Intravascular Large B Cell Lymphoma (IVLBCL) is a rare lymphoma characterized by the proliferation of neoplastic B cells within the lumen of small vessels and can involve the CNS. The clinical presentation is often nonspecific, which delays diagnosis. MRA and CTA are usually normal in IVLBCL because the disease primarily involves small vessels below the resolution of conventional imaging.

Here we describe a case of CNS IVLBCL in which careful angiographic assessment revealed evidence of vasculopathy of the distal cortical branches of the MCA and ACA vessels, providing an early diagnostic clue in suspected IVLBCL.

A 49-year-old man with no medical history presented to the hospital with headache, altered mental status, and episodic left-sided weakness. MRI brain with and without contrast showed two subtle areas of restricted diffusion, with abnormal leptomeningeal enhancement. Lumbar puncture revealed elevated protein and lymphocytic pleocytosis. Given these findings, cerebral angiography was performed to evaluate for vasculitis.

Digital subtraction angiography demonstrated multifocal cortical arterial irregularities within the quaternary distal cortical segments of bilateral MCA and ACA arteries that did not resolve with intraarterial verapamil administration, consistent with a small vessel arteriopathy. A brain biopsy revealed luminal infiltration with invasive atypical B lymphocytes, confirming a diagnosis of IVLBCL.

The patient was treated with methotrexate and CHOP chemotherapy, resulting in an improvement in mental status.

Although IVLBCL is often described as “angio occult” because it preferentially involves vessels below the resolution of conventional angiography, this case demonstrates that careful review of distal cortical branches can reveal multifocal irregularities that CTA and MRA may miss. Higher resolution imaging, like vessel wall MRI may sensitively detect vasculitic changes, but such imaging remains limited to larger academic centers.

A prior case report has also documented angiographic abnormalities in IVLBCL, recognition of such subtle findings may expedite biopsy and treatment.