E3433. WANTED: Have You Seen This Lymphoma? Case Presentations of Two Rare Manifestations of CNS Lymphoma and Differential Diagnostic Mimics
  1. Celeste Hsu; UC San Diego School of Medicine
  2. Yueyang Guo; UC San Diego Health
  3. Connor Zuraski; UC San Diego Health
  4. Nikdokht Farid; UC San Diego Health; UC San Diego School of Medicine
  5. Jennifer Chang; UC San Diego Health
Intravascular lymphoma (IVL) is an aggressive large B-cell lymphoma characterized by intravascular proliferation within small blood vessels, often leading to occlusive symptoms. This entity generally presents with systemic lesions whereas CNS-limited disease is extremely rare with few reported cases in the literature. Lymphomatosis cerebri (LC) is an extremely rare form of primary CNS lymphoma manifesting as rapidly progressive dementia clinically. In this exhibit, we present cases of CNS-limited IVL and LC, and provide a review of the literature with regards to clinical presentation, epidemiology, imaging features, histopathology, and management and prognosis. Additional companion cases will highlight the differential diagnosis.

Educational Goals / Teaching Points
Due to its rarity and difficult diagnosis, there have been no prospective randomized trials evaluating the best treatments of IVL, though methotrexate-based chemotherapy is shown to be beneficial in a subset of patients. In LC, prognosis is poor with no standardized treatment; case reports document use of some combination of high-dose corticosteroids, methotrexate-based chemotherapy, and radiotherapy. Differentials for both CNS-limited IVL and LC include: vasculitis, gliomatosis cerebri, acute demyelinating encephalomyelitis; autoimmune, paraneoplastic, toxic/metabolic and infectious sources; inflammatory cerebral amyloid angiopathy, metastasis, progressive multifocal leukoencephalopathy, and multifocal cerebral infarctions.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
On imaging, both entities are characterized by multifocal or diffuse gray and white matter signal abnormalities with diffusion restriction and leptomeningeal enhancement. LC may additionally present with nodular or masslike enhancement in the areas of signal change.

CNS-limited IVL and LC are both extremely rare disorders that are often misdiagnosed. Early recognition of these diagnostically challenging entities may prevent treatment delays and improve prognosis.