Coexistence of systemic lupus erythematous and myasthenia gravis in a young lady: report of a rare case

The coexistence of Systemic Lupus Erythematous (SLE) and Myasthenia Gravis (MG) is a rare but important concurrence. SLE can proceed or follow MG. The diagnosis of this coexistence is misleading when neither of SLE or MG is pre-diagnosed. A 35-year-old woman with the cumulative symptoms of SLE and MG referred to our center. In spite of four positive criteria of SLE, diplopia and weakness resulting in several fallings which were worsened in the afternoons complicated the diagnosis. During the routine diagnostic approach, a mediastinal mass was observed in the spiral CT scan of the chest, pathologically confirmed as thymoma. Finally, Anti-acetylcholine receptor (AChR) antibody evaluation was performed which the positive result confirmed the MG diagnosis. In conclusion, the association of SLE, MG and thymoma should be taken into account in the management of similar cases. We also suggest clinicians consider the interactive susceptibility factors in these disorders.