Abstract: Objective To enhance clinical awareness of differential diagnosis between anti-Homer3 antibody-associated autoimmune cerebellar ataxia and cerebellar-type multiple system atrophy(MSA-C)through reporting a special case and literature review. Methods A 61-year-old female patient presented with progressive worsening over two years, manifesting as dizziness, ataxia, and dysarthria. Serum and cerebrospinal fluid analyses confirmed positive anti-Homer3 IgG antibodies, with significant symptom improvement following intravenous methylprednisolone therapy. Results Post-immunotherapy cerebellar symptom remission was observed, and the disease progression pattern combined with treatment response characteristics demonstrated that anti-Homer3 antibody-associated autoimmune cerebellar ataxia could closely mimic MSA-C in clinical presentation. Conclusion This case highlights the necessity of comprehensive exclusion of treatable disorders like autoimmune cerebellar ataxia before diagnosing MSA-C. The significant prognostic differences between these conditions emphasize that timely and accurate diagnosis hold crucial clinical significance, as some autoimmune cerebellar ataxia patients may achieve symptomatic improvement through adequate corticosteroid therapy.

Key words: Cerebellar ataxia, Autoimmune, Multiple system atrophy, Differential diagnosis