what causes cholangiocarcinoma
The exact cause of cholangiocarcinoma is unknown, and most cases occur sporadically, but there are several well-defined risk factors. The most common of these is primary sclerosing cholangitis (PSC). The true incidence of cholangiocarcinoma in the setting of PSC is reported as 8%-40%, depending on the type of study.
They start as small submucosal lesions (images). As the carcinoid grows, thickening of the bowel wall occurs, leading eventually to extension outside the bowel wall. Carcinoid tumors can cause an intense desmoplastic reaction with retraction of bowel loops and fibrosis, sometimes leading to bowel ischemia.