Myasthenia gravis in a patient with pauciarticular juvenile chronic arthritis.

There have been reported cases of children with histories of pauciarticular juvenile chronic arthritis (JCA) later developing myasthenia gravis (MG) as young adults. This is intriguing because it had been considered rare to diagnose a second autoimmune disease in a patient with pauciarticular JCA, unlike in those with adult-onset rheumatoid arthritis. We report a case of MG in a 20-year-old woman with a history of pauciarticular JCA. She presented with bilateral ptosis, weakness, and a history of dysphagia. The diagnosis was confirmed with positive serum acetylcholine receptor antibodies (2000 nm/L) and electromyography showing a decremental response to repetitive muscle stimulation. The patient's inflammatory arthritis was quiescent at diagnosis. The patient underwent a surgical thymectomy and was treated with pyridostigmine, intravenous immunoglobulin, and corticosteroids with a fluctuating clinical course. Previous cases have been reported of MG associated with this subtype of JCA, suggesting a connection in autoimmune pathology. The earlier recognition and management of MG in a patient with pauciarticular JCA presenting with weakness may improve the prognosis of this disease.