Thymolipoma-Associated Myasthenia Gravis With High Titer of Anti-Muskab: A Case Report

Myasthenia gravis (mg) is a neuromuscular junction disorder caused by pathogenic autoantibodies to some parts of the post-synaptic muscle endplates. about 85% of generalized mg patients have autoantibodies against postsynaptic acetyl-choline receptors (achr). from the 10-15% of the remaining patients, 45-50% are positive for muscle specific tyrosine kinase-antibody (musk-ab). it is believed that the thymus has a critical role in the pathogenesis of the disease with achr-ab, specially in patients with thymic abnormalities. in contrast, the role of thymus gland in mg with anti-musk-ab is not clearly obvious. patients with this antibody virtually have normal or only minimal follicular hyperplastic thymus. the presence of anti-musk ab in a thymolipomatous (an uncommon tumor of thymus) mg is an atypical and new finding of mg because of not only thymolipoma but the presence of anti-musk antibodies which makes this case different from the previous reports of the antibodies-associated mg. here, we present a young woman with thymolipoma and mg (a very uncommon kind of tumor-associated mg) and high level of anti-musk-ab.