This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory bowel disease, Subject name: Surgery
A middle aged male, who is a diagnosed case of chronic ulcerative colitis, presents to emergency with fever and diarrhea for 1 week and acute onset pain abdomen for 6 hours. An erect abdominal X-ray was taken as shown. What is the likely diagnosis? 
Select and explain. 
A. Pseudomembranous colitis, B. Adenocarcinoma colon, C. Pneumatosis intestinalis, D. Toxic megacolon
D: Toxic megacolon
Answer: D: Toxic megacolon 
Explanation: X-rayshows massively distended transverse colon,ahaustral left colon -History of fever & diarrhea Toxic megacolon: - Life threatening - Occurs in patients of UC and CD . - Diameter > 6 cm - Medical management- Stabilization| Fluids + I/V anti-biotics - TOC - TAC with Ileostomy PMC - No colonic distension, fever & diarrhea Adenocarcinoma colon - No massive distention, fever & diarrhea Pneumatosis intestinalis - Collection of air in the wall of intestine.