2026 American Academy of Neurology Abstract Website

Objective:

N/A

Background:

Central nervous system (CNS) involvement in multiple myeloma (MM) is rare (<1% of cases), characterized by plasma cell infiltration of the cerebrospinal fluid (CSF), meninges, CNS parenchyma, or direct extra-axial extension from adjacent calvarial lesions.

Design/Methods:

N/A

Results:

A 51-year-old woman with recently diagnosed MM status post failed autologous stem-cell transplant presented with painless blurring of vision in the left eye. MRI demonstrated diffuse pachymeningeal enhancement, left optic nerve enhancement, and an enhancing posterior cervical spine lesion. Bone marrow biopsy confirmed relapsed myeloma; lumbar puncture was deferred due to severe thrombocytopenia. Visual symptoms rapidly improved after initiating carfilzomib, pomalidomide, cyclophosphamide, and dexamethasone.

Two and a half months after initial presentation, she developed worsening myeloma markers. Repeat brain MRI revealed a partially ring-enhancing lesion in the left frontal lobe with interval resolution of the cervical lesion. Therapy was escalated to VD-PACE (bortezomib, dexamethasone, cisplatin, doxorubicin, cyclophosphamide, etoposide), and CSF analysis was again deferred due to severe thrombocytopenia. Follow-up brain MRI one month after induction therapy showed near-complete resolution of the frontal lesion, but new leptomeningeal enhancement involving the both trigeminal nerves and internal auditory canals. Subsequent brain MRI demonstrated diffuse parenchymal progression with multiple enhancing cortical, juxtacortical, and subcortical lesions, accompanied by widespread leptomeningeal involvement despite teclistamab and pomalidomide. CSF flow cytometry confirmed plasma cell infiltration consistent with CNS-MM. Three months after intrathecal chemotherapy was initiated, brain MRI showed marked improvement in intraparenchymal disease with residual leptomeningeal enhancement.

Conclusions:

This case illustrates the sequential radiographic evolution of CNS-MM and its heterogeneous presentation. In particular, intraparenchymal MM lesions, not from calvarial extension, are rare. CNS-MM may show a waxing and waning course, with partial radiologic response following therapy escalation while new lesions emerge. Both leptomeningeal and parenchymal patterns can mimic demyelinating or infectious etiologies, underscoring the need for multidisciplinary coordination and close MRI surveillance.