Myasthenia gravis associated with Satoyoshi syndrome: muscle cramps, alopecia, and diarrhea.

We studied a woman who had evidence of myasthenia gravis at age 17. At age 19, she gradually developed alopecia and painful muscle spasms (Satoyoshi disease). Deposition of immune complexes (IgG, C3, and C9) was demonstrated at the motor endplates of limb muscle (biceps brachii); primary synaptic clefts were widened, and postsynaptic folds were simplified. This is the first case of myasthenia and Satoyoshi disease in the same patient.