Pearls & Oy-sters: Reversible Leukoencephalopathy and Parkinsonism Due to CNS Involvement in Cryoglobulinemia.

We present a case of reversible leukoencephalopathy and parkinsonism associated with type III mixed cryoglobulinemic vasculitis in a patient who initially presented with systemic vasculitic symptoms such as rash and arthralgias. Neither hepatitis C nor monoclonal gammopathy-typical triggers of cryoglobulinemia-was identified. The neurologic syndrome evolved with tremor, rigidity, significant cognitive decline, and extensive white matter abnormalities on MRI, mimicking primary neurodegenerative conditions such as multiple system atrophy. Diagnostic workup ruled out infectious, metabolic, autoimmune, and drug-related etiologies. After immunosuppressive therapy with methotrexate and steroids, the patient experienced marked clinical and radiologic improvement, paralleled by a decline in serum neurofilament levels. This case highlights the importance of recognizing inflammatory CNS involvement as a potentially reversible cause of rapidly progressive parkinsonism and cognitive impairment. Prompt identification and timely immunosuppressive treatment may reverse symptoms and prevent permanent neurologic damage.