This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
All of the following extraintestinal manifestations of ulcerative colitis respond to colectomy except ? 
Select and explain. 
A. Primary sclerosing cholangitis, B. Pyoderma gangrenosum, C. Episcleritis, D. Peripheral ahralgia
A: Primary sclerosing cholangitis
Answer: A: Primary sclerosing cholangitis 
Explanation: Ans. is 'a' i.e., Primary sclerosing cholangitis Primary sclerosing cholangitis is the most serious extraintestinal manifestation of ulcerative colitis and it does not resolve with colectomy. Also know these impoant implications of sclerosing cholangitis on ulcerative colitis The activity of the diseased mucosa is more severe in patients with combined ulcerative colitis and primary sclerosing cholangitis. The risk of colonic cancer is five times greater when compared with ulcerative colitis alone. Cancer occurs more on the right side of the colon in patients with primary sclerosing cholangitis and ulcerative colitis.