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.