Registro de caso de miastenia infantil (forma congênita), em criança com 16 meses de idade. Ênfase ao diagnóstico diferencial das várias formas de miastenia na infância é dada durante a discussão do caso. O diagnóstico baseou-se na resposta imediata a teste com Neostigmina, seguido de terapêutica satisfatória com Mestinon.

A rare case of infantile myasthenia gravis (congenital type) is reported. The child was 16 months old at the time of the diagnosis, although she presented signs suggestive of the disease since two months earlier. The diagnosis was based solely upon clinical criteria, including immediate response to a therapeutic test with Neostigmine, followed by excellent response to treatment with Mestinon. A review of the different types of myasthenia gravis in infancy is made, with emphasis on the clinical criteria for differential diagnosis of these cases.