For the first time, a case of myasthenia gravis in combination with damaged bone marrow and an inflammatory muscle disease was reported in a patient.
This rare case was described in the journal Case Reports in Neurology, in the study “Autologous Bone Marrow Transplantation for Polymyositis Combined with Myasthenia Gravis and Aplastic Anemia: A Case Report.”
The Japanese patient, a 54-year-old man, was hospitalized with complains of muscle pain and weakness that had gradually progressed over two months.
He had been diagnosed with myasthenia gravis at age 27, and underwent partial removal of the thymus for malignant tumors, once when he was 27 and again at age 50, followed by four courses of chemotherapy. He was also treated for this disease with 10 mg of prednisolone every other day, and 70 mg of cyclosporine daily.
After the last chemotherapy treatment (age 50), he developed aplastic anemia, a condition characterized by damage to the bone marrow with consequent low levels of all three blood cell types — white and red cells, and platelets.
An initial physical examination did not reveal any abnormalities. Neurological checks showed healthy nerves, and the man had no evidence of difficulty speaking or swallowing, and had control over his eyelids. Motor examination revealed reduced muscle strength affecting both the upper and lower limbs, but normal tendon reflexes.
Blood analysis confirmed the abnormally low blood cell counts, and high levels of the anti-acetylcholine receptor antibody — the hallmark of myasthenia gravis.
The patient also had about 10 times higher-than-usual levels of creatine kinase and 39 times higher levels of myoglobin, suggestive of muscle tissue injury. Imaging data and muscle tissue biopsy confirmed that he had increased muscle inflammation and abnormal tissue organization.
Supported by these findings, the clinical team diagnosed the patient with polymyositis — a type of chronic inflammation of the muscles triggered by autoimmunity — combined with myasthenia gravis and aplastic anemia.
Based on the man’s clinical history, the researchers suggested that these three medical conditions might be caused by “a common thymoma (thymus tumor)-mediated mechanism.” Deregulation of thymus function could have triggered an underlying mechanism shared by all three autoimmune disorders.
He started treatment with intravenous immunoglobulin, 20 mg of prednisolone every other day, and 90 mg of Mestinon (pyridostigmine) and 40 mg cyclophosphamide daily. One month after being given this new diagnosis and starting treatment, his creatine kinase levels dropped significantly, and he showed improved strength in some muscles.
To treat his aplastic anemia, the man underwent a bone marrow transplant at three months post-diagnosis, which helped to return his enzyme levels to within normal levels and to further improve muscle strength.
Researchers believe that this positive outcome suggests that a bone marrow transplant “is a therapeutic option” for people with polymyositis, myasthenia gravis, and aplastic anemia.