Myasthenia gravis associated with human T-cell lymphotropic virus type III infection.

A 15-year-old boy is described with myasthenia gravis, hemophilia A, positive HTLV-III serology, antithyroglobulin and antimicrosomal antibodies, and laboratory evidence of altered cell-mediated immunity. Treatment with pyridostigmine produced dramatic clinical improvement. The results of this patient raise the possibility of myasthenia gravis as the sole or presenting clinical manifestation of infection with HTLV-III.