Abstract
Myasthenia gravis (MG) is characterized by weakness and rapid fatigue of voluntary muscles. Here, we present two cases of early-onset MG, complicated with M-proteinemia and demyelinating neuropathy. Case one was diagnosed with MG at age 29, received tacrolimus post-thymectomy, and developed M-proteinemia and demyelinating neuropathies at age 66 before being diagnosed with B-cell lymphoma. Case two was diagnosed with MG at age 21, received immunosuppressive drugs post-thymectomy, and was diagnosed with myelin-associated glycoprotein antibody-associated neuropathy at age 66. Demyelinating neuropathy with M-proteinuria should be considered when motor symptoms worsen in patients with early-onset MG who receive immunosuppressive drugs after thymectomy.