This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
A patient presents with mediastinal mass with sheets of epithelial cells giving arborizing pattern of reactivity alongwith interspersed lympoid cells. The apt diagnosis would be - 
Select and explain. 
A. Thymoma, B. Thymic carcinoid, C. Primary mediastinal lymphoma, D. Non-Hodgkin lymphoma
A: Thymoma
Answer: A: Thymoma 
Explanation: A thymoma is a tumor originating from the epithelial cells of the thymus that may be benign or malignant. Thymomas are frequently associated with the neuromuscular disorder myasthenia gravis;thymoma is found in 20% of patients with myasthenia gravis. Once diagnosed, thymomas may be removed surgically