Myasthenia Gravis Associated With Thymoma

The goal of this observational study is to investigate the clinical, immunological, and neuromuscular features associated with the development and progression of myasthenia gravis (MG) in adult patients with thymic abnormalities and/or MG-related antibodies, including individuals with or without clinically manifest disease. The main questions it aims to answer are: * Whether integrated clinical, serological, and histopathological profiles are associated with the presence of MG and can predict disease onset or progression * Wheter systemic immune markers are associated with disease activity, progression, and neuromuscular junction alterations Participants will: * Undergo clinical, neurological, and neurophysiological assessments at baseline and during follow-up * Provide blood samples for serological and immunological analyses * Provide thymic tissue and residual intercostal muscle samples (when undergoing clinically indicated thymectomy) for research analyses * Attend follow-up visits at 6, 12, and 18 months * Record daily symptoms using an electronic patient-reported outcome tool (for participants with MG)

This study is a prospective, multi-center, randomized controlled study to evaluate the efficacy and safety of efgartigimod (EFG) and intravenous immunoglobulin (IVIG) in the perioperative application for acetylcholine receptor (AChR) antibody-positive thymoma patients with myasthenia gravis in order to provide reliable evidence for clinical decision-making.

The goal of this observational study is to learn about the experiences of people living with Myasthenia Gravis (MG) in the United States. The main questions it aims to answer are: * How and when are people with MG diagnosed? * What are the most common symptoms associated with MG? * What treatments are being used to treat MG? * What are the impacts of MG on activities of daily living, employment and quality of life? * What are the experiences with exacerbation, hospitalization and healthcare access for people with MG? Participants will answer a survey to enroll in the study, and be invited to fill out an update survey twice a year.