Acute onset anti-MAG neuropathy and paradoxical worsening to rituximab: a challenging case

Background and aim: Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is typically a chronic, progressive, predominantly sensory distal and demyelinating neuropathy, with ataxia and postural tremor Methods and results: Herein we describe an atypical case of anti-MAG neuropathy, characterized by acute lower limb weakness and severe ataxia with difficulty in stance and walking, resembling a Guillain-Barrè Syndrome. The presence of disproportionate distal nerve conduction slowing, and an IgM k monoclonal component have arisen the suspect of anti-MAG neuropathy, confirmed by high titer anti-MAG antibody. Rituximab treatment was started, and patient experienced a dramatic clinical worsening which was rescued by Plasma Exchange. Interpretation: We described an atypical case of anti-MAG neuropathy that was challenging in diagnosis and therapeutic management.