Cancer of the bile duct: the occult malignancy

Primary malignant lesions of the bile duct system are almost always discovered at a late stage, and largely because of this, the prognosis with this disease is poor. Despite this bleak prognosis, many of these lesions are well differentiated and relatively slow growing. In contrast to periampullary lesions, which may be polypoid or papillary with a relatively good prognosis, bile duct cancers are almost always of the infiltrative type and are often scirrhous. Metastases to lymph nodes occur in the majoirty of patients, about half have liver metastases, direct invasion of the liver occurs frequently, extension into the wall of the bile duct often occurs early, periductal involvement often precludes resection, and perineural invasion frequently extends far beyond the limits of resection. The early periductal spread of these lesions along with the anatomic barriers, that is, the portal vasculature, often prevents wide excision of tumors in the supraduodenal portions of the bile ducts. These lesions are difficult to detect accurately and, because of this, often are nonresectable when definitive diagnosis is established. To detect these tumors more frequently during exploration of the extrahepatic biliary system, especially during cholecystectomy, biopsy specimens of any indurated area should be taken. The discovery of white bile in the common duct is highly suggestive of malignant disease, scrapings of indurated areas may establish the diagnosis, and perhaps the interior of the ductal system should be visualized directly with the optical instruments currently available. However, since most intraductal malignant lesions resemble fibrous strictures, direct visualization may not allow distinction between the two; moreover, biopsy may not establish the diagnosis of malignant disease since often the lesions are extensively fibrotic. Retrograde cholangiography with the duodenoscope probably will be used increasingly in the study of various problems in the bile ducts, including malignant disease. It is unlikely, however, that this method will contribute to the discovery of lesions confined to the mucosa, since carcinoma at this stage seldom produces symptoms and duodenoscopy would rarely be carried out in a patient without significant biliary symptoms.