This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Auto Immune Disorders Introduction, Subject name: Pathology
Myasthenia gravis is most commonly associated with which of the following? 
Select and explain. 
A. Thymoma, B. Thymic carcinoma, C. Thymic hyperplasia, D. Lymphoma
C: Thymic hyperplasia
Answer: C: Thymic hyperplasia 
Explanation: Myasthenia gravis Autoimmune disease with fluctuating muscle weakness that is caused by autoantibodies that target the neuromuscular junction. About 85% of patients have autoantibodies against post-synaptic ACh receptors, while most of the remaining patients have antibodies against the sarcolemmal protein muscle-specific receptor tyrosine kinase. C/F: - Ptosis or diplopia (Weakness in extraocular muscle) There is a strong association between pathogenic anti-ACh receptor autoantibodies and thymic abnormalities. Approximately 10% of patients with myasthenia gravis have a thymoma, a tumour of thymic epithelial cells. An additional 30% of patients (and paicularly young patients) have a different thymic abnormality called thymic hyperplasia. Acetylcholinesterase inhibitors that increase the half-life of ACh are the first line of treatment.