Rare cases of malignant melanoma, a tumor that usually arises from the skin, and malignant lymphoma, that usually arises in the lymph nodes, can originate from the biliary tract or its surrounding tissues. It is important to distinguish these cancers from usual biliary carcinomas, since their treatment is different. Children almost never develop carcinomas of the biliary tree. Patients are usually in their 60's when they first show signs of disease, and there is a slight female predominance. PSC causes progressive scarring and narrowing of the bile ducts, which block bile from reaching the intestines.
Many patients eventually develop liver failure, necessitating liver transplant.
It is thought that the progressive epithelial injury and subsequent regeneration predisposes patients with PSC to carcinoma. More than half of patients with PSC have a history of another autoimmune disorder, idiopathic inflammatory bowel disease. This is most often ulcerative colitis. It is thought that prolonged sludging of bile in these dilated spaces and subsequent infection predispose patients to carcinoma, again through progressive epithelial injury and repair. Clonorchis is acquired when humans eat fresh water fish that harbor the Clonorchis cyst.