Association between myasthaenia gravis and systemic lupus erythematosus: three case reports and review of the literature

The coexistence of systemic lupus erythematosus (SLE) and myasthaenia gravis (MG) has been reported previously. Because of their shared clinical characteristics and autoantibody-mediated pathogenesis, an SLE expert panel decided to include MG as one of the 19 neuropsychiatric SLE syndromes. This study reports a cluster of three cases of SLE/MG overlap from our cohort and a review of the published data concerning this overlap of SLE and MG. A systematic Medline review revealed 13 cases described in eight publications from 1994 to 2009. In summary, 12 of the 16 patients (three from our cohort and 13 from the reported cases) were women with an average age of 34 years. The most common SLE manifestations were polyarthritis (15 out of 16 patients), skin rashes (5/16), serositis (5/16), and cytopaenias (10/16). All of the patients were anti-nuclear antibodies (ANA) positive and 15/16 were anti-dsDNA positive. Proximal muscle weakness was the most frequent MG-related symptom (9/16), while 11/16 patients were anti-acetylcholine receptor (anti-AChR) antibody positive and 9/16 had diagnostic electromyography (EMG). These data suggest that MG should to be included in the differential diagnosis of lupus patients with fatigue and muscular weakness together with inflammatory and drug-induced myopathy.