Is Satoyoshi syndrome an autoimmune disease? A systematic review

Objectives: Satoyoshi syndrome is a rare multisystem disease of presumed autoimmune aetiology. We carried out a systematic review to evaluate the available evidence to support that autoimmune hypothesis. Methods: We searched for Satoyoshi syndrome cases in PubMed, the Web of Science and Scopus up to January 2022, using keywords 'Satoyoshi syndrome' or 'Komuragaeri disease'. Data on symptoms, associated autoimmune diseases, presence of autoantibodies and response to treatment were collected. Results: A total of 77 patients from 57 articles published between 1967 and 2021 were included; 59 patients were women. The mean age at diagnosis was 21.2 years. All cases had painful muscular spasms and alopecia. Frequent manifestations included: diarrhoea, malabsorption, growth retardation, amenorrhoea and bone deformity. Satoyoshi syndrome was associated with other autoimmune diseases: myasthenia gravis, autoimmune thyroiditis, idiopathic thrombocytopenic purpura, atopic dermatitis, bronchial and lupus erythematosus. Autoantibody determinations were performed in 39 patients, of which 27 had positive results. The most frequently detected autoantibodies were ANAs. Other less frequently found autoantibodies were: anti-acetylcholine receptor antibodies, anti-DNA antibodies, antithyroid antibodies, anti-glutamic acid decarboxylase (anti-GAD) and anti-gliadin antibodies. Pharmacological treatment was reported in 50 patients. Most of them improved with CS, immunosuppressants and immunoglobulins, or a combination of these medications. Conclusion: Satoyoshi syndrome is associated with other autoimmune diseases and a variety of autoantibodies. Improvement after CS or other immunosuppressant treatment was observed in 90% of cases. These data support an autoimmune aetiology for Satoyoshi syndrome. More studies including systematic determination of autoantibodies in all patients with Satoyoshi syndrome will help us advance in our understanding of this disease.