This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology and Rheumatology, Subject name: Medicine
This smoker presented with a four-year history of blanching of the fingers on exposure to cold. What is the diagnosis? 
Select and explain. 
A. Thromboangiitis obliterans, B. Marantic endocarditis, C. Kawasaki disease, D. Brachial entrapment syndrome
A: Thromboangiitis obliterans
Answer: A: Thromboangiitis obliterans 
Explanation: Answer A. Thromboangiitis obliterans Thromboangiitis obliterans is a vaso-occlusive disease that involves small- and medium-sized vessels of the upper and lower extremities. It is strongly associated with tobacco use. An angiogram of this patient's right hand demonstrated multiple chronic occlusions of the digital branches that were unresponsive to intraarterial vasodilators, supporting the diagnosis of thromboangiitis obliterans.