Adult-onset Satoyoshi syndrome in a young male.

Satoyoshi syndrome is a rare condition of presumed autoimmune etiology that is characterized by intermittent painful spasms, diarrhea, hair loss, and bone abnormalities. We report the first case of adult onset Satoyoshi syndrome in South America. A 32-year-old Caucasian male presented with sudden involuntary muscle contractions and painful cramps that had started at the age of 21. He also presented with trismus and complete loss of body hair. Electroneuromyography showed abnormal spontaneous activity. Diagnosis of Satoyoshi syndrome was made after extensive investigation; improvement was achieved with corticosteroids and azathioprine. It is a rare disease; few cases have been described worldwide, most of them in Asian children and almost all sporadic. There are several atypical presentations described in the literature. Immunosuppression is the basis of treatment. Professionals dealing with neuromuscular diseases should be aware of this condition and its atypical presentations, given the possible response to immunosuppressive treatment.