[Langerhans cell histiocytosis associated with myasthenia in an infant].

The pathogenesis of Langerhans cell histiocytosis (LCH) is unclear, but there is increasing evidence that an immunological dysfunction is present. We describe an infant who presented a LCH associated with myasthenia gravis. The thymus is known to play an important role in the pathophysiology of myasthenia gravis and is often involved in LCH. Infancy and signs of organ dysfunction are predictive of poor prognosis: immunotherapy is to be investigated (thymic hormone, cyclosporin, alpha interferon), as well as allogeneic bone marrow transplantation.