This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
A 45-year-old woman who smokes is found to have a splenic artery aneurysm. It was most likely caused by: 
Select and explain. 
A. Atherosclerosis, B. Trauma, C. Medial dysplasia, D. Pancreatitis
C: Medial dysplasia
Answer: C: Medial dysplasia 
Explanation: Splenic artery aneurysms in women are almost always caused by medial dysplasia of the artery. It may be the cause of rupture in pregnancy and can be life-threatening if not treated promptly by laparotomy. Aneurysms may be caused by atherosclerosis, trauma, and pancreatitis (when complicated by pseudocyst formation). Portal hypertension is not a cause of aneurysm.