Systemic lupus erythematosus and myasthenia gravis: More common than we think?

Systemic lupus erythematosus and myasthenia gravis are autoimmune disorders whose association in the same patient has been rarely reported. An account of three cases of SLE and myasthenia coexisting in the same patients is being presented with a review of currently available literature. Case 1 was a 33-year-old female fulfilling 6 SLICC classification criteria for SLE. She developed diplopia, dysphagia, and hoarseness of voice. A CT thorax done for evaluation of pulmonary hypertension showed thymic enlargement and serum anti-acetylcholine receptor antibody was positive. The patient was treated with pyridostigmine for myasthenia gravis with clinical improvement and a subsequent 10-year uneventful follow-up. Case 2 was a 22-year-old girl with new onset proximal muscle weakness after 5 years of immunosuppressive therapy for SLE. Other potential causes of proximal weakness were ruled out. A diagnosis of myasthenia gravis was made based on anti-acetylcholine receptor antibody positivity. She later succumbed to respiratory involvement despite therapy. Case 3 was a case of myasthenia gravis diagnosed at 28 years of age based on decremental response on repetitive nerve stimulation (RNS), who presented 6 months later with pregangrenous changes in her foot. She tested positive for antiphospholipid antibody and satisfied 6 SLICC criteria for classification as SLE. She is now on treatment, well, and on long-term follow-up. In patients with SLE, development of fatigue, neurological manifestations, and muscle weakness requires a high index of suspicion to prompt a search for myasthenia in addition to myositis and drug-induced myopathy.