Myasthenia gravis in association with allogeneic bone marrow transplantation: clinical observations, therapeutic implications and review of literature.

Myasthenia gravis (MG) is a rare complication of allogeneic bone marrow transplantation (BMT). We present the 11th case in the medical literature, a 23-year-old female 100 months post-allogeneic bone marrow transplantation for acute myelogenous leukemia (AML). After discontinuation of immunosuppression for chronic graft-versus-host disease (GVHD) involving skin, gastrointestinal tract and lacrimal glands, the patient developed severe, progressive dysphagia initially attributed to esophageal candidiasis. With the development of muscle weakness, ptosis, and dysphonia the diagnosis of generalized myasthenia gravis was suspected, and confirmed by elevated anti-acetylcholine receptor antibody titer and a positive edrophonium challenge. Prednisone and pyridostigmine produced improvement, and thymectomy was performed without pathologic evidence of thymoma. Recurrent post-operative respiratory distress required transient mechanical ventilation. Twenty-seven months after diagnosis, the patient requires maintenance prednisone to control symptoms of myasthenia gravis. The clinical features of all reported cases of MG post-allogeneic BMT are reviewed, and universal features include an association with decreasing immunosuppression, the presence of other manifestations of chronic GVHD, anti-acetylcholine receptor antibodies, and the absence of an associated thymoma. HLA Cw1, Cw7 and DR2 were identified at frequencies significantly above that expected from HLA antigen prevalance studies, and may be markers for increased risk of developing MG post-allogeneic BMT. No statistically significant associations with HLA A2, B7, B35 or donor-recipient sex mismatch were present. Reinstitution of immunosuppression and standard therapies for myasthenia gravis were effective in the majority of cases. The role of thymectomy in this population remains unclear.