GIT

Oral cavities &Gastrointestinal tract pathologyLec 2Dr. Zahraa Marwanlecturer in Mosul medical college


ESOPHAGUS.Develops from cranial part of foregut .In adults it measures 25 cm and extends from the epiglottis at the level of C6 to gastroesophageal junction at T11 or T12.Anatomic luminal narrowings  -proximal (cricoid cartilage)  -midway (aortic arch) -distal (diaphragm)

.physiologic sphincters, (UES, LES).histology, (mucosa, sub-mucosa, muscularis propria, adeventia).main functions -conducts nutrients from pharynx to stomach -prevents passive diffusion of substances from lumen to blood -prevents reflux of gastric contents

Atresia: .a segment of esophagus of non- canalized cord associated with: -fistula with a bronchus or trachea -congenital heart defects -genito-urinary malformations -neurologic disease

Esophageal atresia and tracheo-esophageal fistula

Achalasia : .characterized by -aperistalsis -incomplete relaxation of the LES  -increased resting tone of the LES.primary, (idiopathic) .secondary to, (Chagas disease, damage of dorsal motor nuclei, diabetes, infiltrative lesions)

.morphology: -progressive dilation of the esophagus above the level of LES -myenteric ganglia are absent .clinical features -Progressive dysphagia - Dyspepsia, aspiration -Carcinoma develops in 5% of cases

Progressive dilation of esophagus above LES, variable wall thickness Narrowing of LES (Bird- Beak appearance)


Reflux Esophagitis (GERD): .causes, (conditions that decrease LES tone or increase abdominal pressure) : -abuse of alcohol and tobacco -obesity and pregnancy -CNS depressants -hiatal hernia -delayed emptying and increased volume of stomach

.clinical features: -dysphagia -heartburn -regurgitation of sour brash -hematemesis and/or melena .potential complications: -bleeding -ulceration -stricture -Barrett esophagus

Barrett Esophagus: .distal intestinal metaplasia within esophageal squamous epithelium, secondary to long-standing gastro- esophageal reflux .affects 40-60 years people .diagnosis is made when the columnar mucosa contains intestinal goblet cells .complication is adenocarcinoma

Barrett esophagus

TumorsBenign mesenchymal (leiomyoma)polyps (fibroepithelial)Malignant squamous cell carcinomaadenocarcinoma

Squamous Cell Carcinoma .age incidence, above 50 years with M:F ratio of 4:1 .risk factors -alcohol and tobacco use -caustic esophageal injury -achalasia -Plummer-Vinson syndrome -hot beverages


.pathogenesis -loss of tumor suppressor genes -dietary factors (alcohol, tobacco, deficiency states)  -carcinogens (fungus, nitrosamines)  -HPV infection.morphology  -most affected part is middle third, as plaque-like thickening of the mucosa -most are of low grade

.clinical features  -dysphagia  -odynophagia -gradual obstruction  -weight loss -bleeding -sepsis .prognosis -five years survival rate is 9%

Adenocarcinoma : .most cases arise from Barrett mucosa. .etiology and pathogenesis: -stepwise accumulation of genetic changes -obesity -tobacco smoking -prior radiation therapy



 .Morphology: -raised patch -nodule -diffusely infiltrative lesion, with mucin- producing glands

Esophagus, adenocarcinoma squamous carcinoma

 .clinical features -affects patients older than 40 years who suffer from .progressive dysphagia .weight loss .hematemesis and melena

STOMACH

.develops from distal part of foregut, with a capacity of 3000 mL

.the wall consists of -mucosa -submucosa -muscularis propria -serosa.mucosa has 2 compartments, -superficial foveolar -deeper glandular  .mucus-secreting glands (cardia) .oxyntic glands (fundus, body) .mucus-endocrine glands (antrum)

.main cells of the oxyntic glands -mucous cells (mucus, pepsinogen I,II) -parietal cells (acid, intrinsic factor) -chief cells (pepsinogen I,II) -neuroendocrine cells (gastrin, histamine, somatostatin, endothelin).interior of stomach form rugae 

.gastric function is secretion of hydrochloric acid for digestion of food, secretion of HCL has 3 phases -cephalic -gastric -intestinal .autodigestion is prevented by -secretion of mucus, bicarbonate, and prostaglandin -epithelial barrier -mucosal blood flow

Acute Gastritis: .usually transient mucosal inflammation .pathogenesis, one or more may operate:  -increased acid secretion -decreased bicarbonate secretion -reduced blood flow -disruption of adherent mucus layer -direct epithelial damage


.causative factors: -heavy use of NSAIDs, alcohol, smoking -radiation and chemotherapy -ischemia, shock, and uremia -infection, (H.pylori) -stress (trauma, burns, surgery) -ingestion of chemical (acids, alkali) -mechanical trauma -distal gastrectomy

.morphology: -surface epithelium is intact -presence of neutrophils within epithelium -in severe cases erosion with or without hemorrhage .clinical features -asymptomatic -epigastric pain, nausea, vomiting -hematemesis

Acute gastritis: hyperemic edematous gastric mucosa with foci of superficial erosions.

Acute Gastric Ulceration:.range from erosions to ulcerations .causes: -therapy with NSAIDs -severe physiologic stress.types: -stress ulcers (shock, sepsis, severe trauma) -Curling ulcers (severe burns, trauma) -Cushing ulcers (intracranial disease)

A 1 cm acute gastric ulcer is shown here in the upper fundus. The ulcer is shallow and sharply demarcated, with surrounding hyperemia. It is probably benign.

Chronic Gastritis: .etiology and pathogenesis -chronic infection by H. pylori -autoimmunity -toxic (alcohol, tobacco) -postsurgical (reflux of duodenal secretion) -motor and mechanical -radiation -granulomatous conditions

Helicobacter Pylori-Induced Chronic Gastritis:.H. pylori is gram negative rod presents in gastric biopsy of: -almost all patients with duodenal ulcers -majority of individuals with gastric ulcers or chronic gastritis

 .pathogenesis: -possible routes of transmission .oral-oral .fecal-oral .environmental -microbe virulence depends on: .motility via flagella .elaboration of urease and toxins  .expression of adhesins

.morphology: -organism within superficial mucus in the surface and neck regions of antrum  -intraepithelial neutrophils and sub- epithelial plasma cells -atrophic mucosa  -lymphoid aggregates>lymphoma

Stomach, Helicobacter gastritis

.diagnosis depends on -noninvasive tests, (serologic, fecal bacterial detection, urea breath test) -invasive tests, (biopsy), identification of microbe .histologic section .bacterial culture .rapid urease test .bacterial DNA by PCR

Peptic Ulcer Disease: .most often solitary, that occurs in any portion of the gastrointestinal tract exposed to acid/peptic juice .chronic recurring lesion, diagnosed in middle-aged to older adults, with a M:F ratio of 3:1 in duodenal ulcer and 2:1 in gastric ulcer

.pathogenesis -imbalance between gastro-dudenal mucosal defense mechanisms and the damaging forces (gastric acid and pepsin), hyperacidity is not necessary -H. Pylori infection is a major factor, presents in all patients with duodenal ulcer and in 70% with gastric ulcers, only 20% of patients infected with H. pylori have peptic ulcer

 -co-factors include, (NSAIDs, tobacco smoking, high-dose corticosteroids) -associated conditions .alcoholic cirrhosis .COPD .chronic renal failure .hyperparathyroidism .psychological stress

Mechanisms of gastric injury

.morphology : -duodenal ulcers, within few centimeters of pyloric ring on anterior wall -gastric ulcers, along lesser curvature -up to 20% of patients with gastric ulcer have a coexistent duodenal ulcer -most are<2 cm in diameter round to oval, sharply punched-out with clean base and straight walls and margins are level with the surrounding mucosa or slightly raised

Chronic gastric ulcer:the ulcer is rounded covered by necrotic surface , note the radiating thickened mucosal folds due to underlying fibrosis.

.in active ulcers 4 zones are seen microscopically -base and margins have thin layer of fibrinoid debris -zone of nonspecific inflammation -deeper to it is granulation tissue -deepest is fibrous tissue

Peptic ulcer, perforated gastric ulcer ulcer base, granulation tissue


.clinical features -epigastric pain, 1-3 hours after meals during the day, relieved by alkali or food, pain is worse at night -nausea, vomiting, bloating, belching, and significant loss of weight .complications  -bleeding (most frequent) -perforation -obstruction from edema and scarring