DISEASES OF THE DIGESTIVE SYSTEM Eman MS Muhammad
DISEASES OF THE STOMACH • CONGENITAL PYLORIC STENOSIS • The condition is manifested in infants 2-4 weeks old. • The pylorusismarkedly thickened due to hypertrophy of the circular muscle fibers and the lumen is markedly narrowed. • The infant suffers from regurgitation of fluids followed by projectile vomiting. • Dehydration and alkalosis results. • The disease is explained by immaturity or diminished number of the myenteric ganglion cells.
GASTRITIS • Acute Gastritis: • Causes: • Indigestible, spicy or decomposed food • Bacterial toxins in infectious diseases • Excess alcoholics • Aspirin • Cytotoxic drugs • Stress conditions • Renal failure
Pathology: • Catarrhal inflammation in which the mucosa is hyperemic, edematous and covered by excess mucous • Petechial hemorrhage and small superficial ulcerations may occur
Chronic Gastritis: • Etiology: (1) Chronic infection specially by Helicobacter pylori (2) Autoimmune gastritis due to formation of antibodies against parietal cells causing their destruction and atrophy (3) Toxic effects of excess alcohol and tobacco (4) Exposure to radiations (5) Crohn's disease, amyloidosis and uremia
Pathological features: (1) Infiltration of the lamina propria by inflammatory cells mainly plasma cells and lymphocytes. (2) Atrophy of the glandular epithelium. (3) Gastric mucosa may show intestinal metaplasia and dysplasia.
Types: • Chronic superficial gastritis: • The inflammatory infiltrate is limited to the foveolar region and unaccompanied by glandular atrophy. (2) Chronic atrophic gastritis: • Inflammation is more extensive and accompanied by glandular atrophy. • According to the degree of atrophy, chronic atrophic gastritis is classified into mild, moderate and severe types.
ACUTE ULCERS OF STOMACH AND DUODENUM • Acute ulcers are stress ulcers due to increased hydrochloric acid and pepsin secretion. • They occur in association with cerebrovascular accidents, hypothalamic lesions, steroid therapy and severe burns. • The ulcers are multiple, tiny, superficial and covered by blood pigments. • The ulcers heal on removal of the cause.
CHRONIC PEPTIC ULCERS • Sites: (1) The first part of the duodenum. (2) Lesser curvature of the pyloric antrum of the stomach. (3) The lower part of the esophagus (Barrett's mucosa). (4) The jejunum after gastro-enterostomy. (5) Meckel's diverticulum if it contains ectopic gastric mucosal tissue.
Duodenal and gastric ulcers are the commonest with a ratio of 10:1 in Egypt. • They occur at any age but commonly between 20-40 years. • Male to female ratio is 3:1. • Etiology: • Predisposing factors: • Spicy and hot food, tobacco, aspirin, steroids and psychological factors as mental tension and strain.
Pathogenesis of duodenal ulcer: (1) Hereditary predisposition: (a) Strong family history (b) More common in people with blood group 0. (2) Hyperacidity caused by: (a) Increased number of parietal cells causing hyperchlorhydia. (b) Increased vagus tone causing hypersecretion of the gastric juice. (c) Zollinger-Ellison syndrome: Gastrinoma which is a gastrin-secreting tumor of the pancreas causes gastric hypersecretion and hyperacidity. (3) Infection by Helicobacter pylori.
Pathogenesis of gastric ulcer: (l) Devitalization of the gastric mucosa caused by: (a) Impaired mucus-bicarbonate barrier (b) Decrease mucosal blood in ischemia and shock (c) Chronic gastritis specially caused by Helicobacter pylori (d) Duodenal-gastric reflux where bile and pancreatic juice cause mucosal injury. (e) Delayed gastric emptying (2) Traumatic effect of food on a normal or devitalized mucosa causes ulcers mainly on the lesser curvature. • Acid secretion is normal or reduced.
Pathology: • Sites: • Gastric ulcers are common along the lesser curvature of the pyloric antrum. • Duodenal ulcers occur in the first part, more common in the anterior wall. • Gross picture: • Size: • Gastric ulcers are 1-3 cm in diameter, while duodenal ulcers are usually about 1 cm in diameter.
Shape: • Rounded or oval. • A saddle-shaped ulcer may occur in the stomach. • It overrides the lesser curvature and extends on both surfaces. • Margin: • The mucosa around the ulcer, is smooth and atrophic. • Edge: • Sloping or step-like. • Floor: • Is clean and made of the serosa or the remains of the muscle layer.
Base: • Is indurated due to the extensive fibrosis. • Outer serosal covering: • Appears opaque white and puckered due to fibrosis, and adherent to the surrounding structures. • Microscopic picture: • The base of the ulcer shows two layers: (1) A superficial layer of granulation tissue infiltrated by neutrophils. Its top part is necrotic. (2) A deeper layer of fibrous tissue showing remains of the muscle layer, foci of chronic inflammatory cells and endarteritis obliterans.
Complications: (1) Hemorrhage: Causes: (a) The traumatic effect of food on the, granulation tissue in the floor of the ulcer (b) Erosion of a vessel in the floor or the wall of the ulcer. • Hemorrhage causes hematemesis and melena. (2)Perforation: • Occurs in 10% of the cases. • Perforation is precipitated by heavy meals or drugs as steroids and phenylbutazone. • Perforation of a gastric ulcer results in localized or diffuse peritonitis. • A duodenal ulcer may perforate into the peritoneum or penetrate into the pancreas causing pancreatitis.
(3)Cicatricial contraction: • Causes pyloric or duodenal stenosis. • Fibrosis of a saddle shaped ulcer on the lesser curvature pull on the greater curvature constricting the stomach in the middle i.e. hour-glass stomach. (4)Malignant change: • Occurs in 1-2% of the gastric ulcers.
"Hourglass" stomachDue to chronic peptic ulceration there is fibrosis & contracture ofthe stomach leading to an hourglass shape as well as altered mobility
TUMOURS OF THE STOMACH I. Benign tumors: • Adenoma (adenomatous polyp): • A rare single or multiple tumor. • The size from few millimeters up to 4 cm. • Its effects are ulceration and bleeding, pyloric obstruction and malignant transformation.
(2)Leiomyoma: • A common tumor of the smooth muscle which may project under the mucosa or serosa. • The covering mucosa may ulcerate and bleed. • The tumor may change to leiomyosarcoma. (3)Leiomyoblastoma, fibroma, neurofibroma, lipoma and angiomas:are rare tumors.
II. Malignant tumors: (1) Carcinoma: 70% of the malignant tumors (2) Carcinoid tumor. (3) Sarcomas: • Leiomyosarcoma, fibrosarcoma, liposarcoma and malignant lymphoma.
GASTRIC CARCINOMA • Gastric carcinoma is more common in males in the fifth and sixth decades. • The tumor is common in Japan, but rare in Africa. • Precancerous Lesions: • Gastric adenoma • Chronic gastritis • Chronic peptic ulcer • Smoked or salted meat or fish • More common in persons with blood group A
Site: • All parts of the stomach may be involved, but most gastric carcinomas occur in the antrum, pylorus, cardia and lesser curvature. • Gross picture: (1) Polypoid or fungating carcinoma: • Large fungating mass which projects into the lumen of the stomach with surface ulceration and secondary infection. (2) Ulcerative carcinoma: • A malignant ulcer, more than 3 cm in diameter with raised everted edge and indurated base.
(3) Infiltrating carcinoma: Which is either: (a) Localized type: • Affects the pyloric region. • The wall becomes thick and rigid and the lumen is moderately reduced. • The rest of the stomach dilates. (b) Diffuse type: • The whole stomach wall is infiltrated by the malignant growth which shows marked fibrosis. • The wall becomes thick and leathery and the lumen is markedly reduced "Leather bottle stomach". • There is no mucosal ulceration.
Microscopic picture: (1) Adenocarcinoma: • The polypoid and ulcerative carcinoma are usually moderately differentiated adenocarcinoma. • This is the commonest type. (2) Mucoid carcinoma: • Secrete abundant mucin. (3) Signet-ring cell carcinoma. (4) Undifferentiated carcinoma.
Spread: (1) Direct spread: • Through the stomach wall to the pancreas, liver, colon, spleen and omentum. (2)Lymphatic spread: • To the lymph nodes along the lesser and greater curvature, next to the nodes at the hilum of the liver and around the celiac artery and lastly to the para-aortic and left supra-clavicular lymph nodes.
(3)Blood spread: • By the portal vein to the liver then to the lungs, bones and brain. (4) Transcelomic spread: • The tumor forms implants on the surface of the pelvic organs specially the ovary called Krükenberg tumor. • Hemorrhagic ascitis may result.
Effects: (1) Hemorrhage: • Usually chronic causing microcytic hypochromic anemia. • Gastric hemorrhage is manifested as hematemesis and melena. (2) Pyloric obstruction. (3) Mucosal destruction causes hypochlorhydria or achylia. • Deficiency of the intrinsic factor may cause macrocytic anemia.
HAEMATEMESIS • Definition: • Vomiting of blood. • Causes: (1) Diseases of the esophagus: • Varicose veins, esophagitis, peptic ulcer, carcinoma, mediastinal tumors infiltrating the esophagus or aortic aneurysm rupturing in the esophagus. (2)Diseases of the stomach: • Gastritis, acute ulcers, peptic ulcers and gastric tumors specially carcinoma.
(3)Diseases of the duodenum: • Acute ulcers, peptic ulcer and tumors. (4)Blood diseases: • Hemophilia, purpura and leukemias. (5)Vitamin deficiency: • Vitamin C and K.