Arthritis, ankylosing spondylitis, erythema nodosum, and pyoderma gangrenosum typically improve or completely resolve after colectomy.
PSC occurs in 5% to 8% of patients with ulcerative colitis.
HLA-B8 or HLA-DR3 haplotype are 10 times more likely to develop PSC.
The risk for colon cancer in these patients is up to five times greater than in patients with ulcerative colitis alone. These tumors are more likely to arise proximal to the splenic flexure . Colectomy has no effect on the course of PSC.