Suspected central nervous system involvement in multiple myeloma on MRI

Central nervous system involvement in multiple myeloma (CNS-MM) is rare, typically appearing at relapse and associated with poor prognosis. We report the case of a 67-year-old woman with high-risk IgA lambda multiple myeloma who developed early relapse with extensive extramedullary disease and atypical brain MRI findings. Imaging revealed abnormal thickening and heterogeneous enhancement of the pituitary stalk as well as signs suggestive of cerebral venous sinus thrombosis (CVST), raising suspicion of CNS involvement. Cerebrospinal fluid analysis was not performed due to rapid clinical deterioration, leaving the diagnosis probable rather than confirmed. This case is notable for its unusual site of CNS manifestation and rapid progression despite multiple lines of therapy. It highlights the diagnostic uncertainty surrounding Central nervous system involvement in multiple myeloma (CNS-MM) and emphasizes the importance of integrating imaging and clinical data for timely recognition of this rare and aggressive complication.