This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Myasthenia Gravis and Muscular dystrophy, Subject name: Medicine
In a case of myasthenia gravis, CT Chest shows anterior mediastinal mass. Diagnosis is? 
Select and explain. 
A. Retrosternal goiter, B. Thymic Hyperplasia, C. Hilar Lymphadenopathy, D. Aoic Aneurysm
B: Thymic Hyperplasia
Answer: B: Thymic Hyperplasia 
Explanation: Thymus gland abnormalities are seen in 75% of anti-Ach Receptor positive antibodies patients. CT chest can identify a Thymic hyperplasia or a thymoma which though benign can produce mass effects.