This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Radiology
Fat ring sign is positive in? 
Select and explain. 
A. Mesenteric panniculitis, B. Lymphoma, C. Carcinoid, D. Desmoid tumor
A: Mesenteric panniculitis
Answer: A: Mesenteric panniculitis 
Explanation: Ans AFat ring signQ is preservation of fat around the mesenteric vessels and around soft tissue nodules on a background of fat stranding in mesenteric panniculitis or mesenteric lipomas. Also known as a fat halo sign