tailieunhanh - Diseases of the Liver and Biliary System - part 10

Đặc điểm lâm sàng Cả hai giới đều bị ảnh hưởng, nhưng nam giới thường xuyên hơn so với nữ giới trong một tỷ lệ 2: 1. Người bệnh thường là từ 50 đến 69 tuổi. Những hình ảnh lâm sàng là một tổng hợp của ứ mật suy tụy | 640 Chapter 36 found in the pancreatic juice of patients with chronic pancreatitis. This may relate to K-ras mutations in areas of duct hyperplasia 41 . Over a 2-year follow-up a minority develop pancreatic carcinoma 40 . Pathology Histologically the tumour is an adenocarcinoma whether arising from pancreatic duct acinus or bile duct. The ampullary tumours have a papillary arrangement and are often of low-grade malignancy fibrosis is prominent. They tend to be polypoid and soft whereas the acinar tumours are infiltrative large and firm. Obstruction of common bile duct This results from direct invasion causing a scirrhous reaction from annular stenosis and from tumour tissue filling the lumen. The duct may also be compressed by the tumour mass. The bile ducts dilate and the gallbladder enlarges. An ascending cholangitis in the obstructed duct is rare. The liver shows the changes of cholestasis. Pancreatic changes The main pancreatic duct may be obstructed as it enters the ampulla. The ducts and acini distal to the obstruction dilate and later rupture causing focal areas of pancreatitis and fat necrosis. Later all the acinar tissue is replaced by fibrous tissue. Occasionally particularly in the acinar type fat necrosis and suppuration may occur in and around the pancreas. Diabetes mellitus or impaired glucose tolerance is found in 60-80 of patients. Apart from destruction of insulin-producing cells by the tumour this may be due to production of islet amyloid polypeptide IAPP by islet cells adjacent to the tumour 36 . Spread of the tumour Direct extension in the wall of the bile duct and infiltration through the head of the pancreas is common with the acinar although not with the ampullary type. The second part of the duodenum may be invaded with ulceration of the mucosa and secondary haemorrhage. The splenic and portal veins may be invaded and may thrombose with resultant splenomegaly. Involvement of regional nodes is found in approximately a third of operated cases.