Pathology of GIT- Intestine

Small & Large Intestine

Oct. 11. 2015

SMALL/LARGE INTESTINE

NORMAL: Anat., Vasc., Mucosa, Endocr., Immune, Neuromuscular.
PATHOLOGY:
CONGENITAL
ENTEROCOLITIS: DIARRHEA, INFECTIOUS, OTHER
MALABSORPTION: INTRALUMINAL, CELL SURFACE, INTRACELL.
(I)IBD: CROHN DISEASE and ULCERATIVE COLITIS
VASCULAR: ISCHEMIC, ANGIODYSPLASIA, HEMORRHAGIC
DIVERTICULOSIS/-IT IS
OBSTRUCTION: MECHANICAL, PARALYTIC (ILEUS) (PSEUDO)
TUMORS: BENIGN, MALIGNANT, EPITHELIAL, STROMAL

SMALL/LARGE INTESTINE ANATOMY

SI = 6 meters,
LI = 1.5 meters



Serosa/ adv.
Muscle
Submucosa
Mucosa
MALT

MUCOSA

Small Intestine

Large Intestine

CONGENITAL

DUPLICATION
MALROTATION
OMPHALOCELE
GASTROSCHISIS
ATRESIA/STENOSIS SPECTRUM
MECKEL (terminal ileum, “vitelline” duct)
AGANGLIONIC MEGACOLON (HIRSCHSPRUNG DISEASE)


Omphalocele occurs when closure of the abdominal musculature is incomplete and the abdominal viscera herniate into a ventral membranous sac.

Intestinal Obstruction

Infarction

Tumor
20%
80%

OBSTRUCTION

ILEUS, esp. postsurgical
INFARCTION
MOTILITY DISEASES, esp., HIRSCHSPRUNG DISEASE.


Ileus is a disruption of the normal propulsive GIT motor activity from NON-mechanical mechanisms

Congenital defect in colonic innervation

M>F
1/5000
Failure of migration of neural crest cells from cecum to rectum.
Functional Intest obstraction
Rectum and sigmoid
Complications; (Colitis, perfor. Peritonitis).

Hirschsprung diseaseCong. Aganglionic Megacolon

The aganglionic region may have normal or narrow appearance, while the normally innervated proximal colon undergo progressive dilation.
Dx; Distal intestinal segment lacks both the Meissner (submucosal) & Auerbach (myenteric) plexus (“aganglionosis”).
• Hirschsprung diseaseCong. Aganglionic Megacolon

Hirschsprung disease

VASCULAR DISEASES

• ISCHEMIA/INFARCTION

Hemorrhagic
Venous
Arterial
• ANGIO-”DYSPLASIA”*
• HEMORRHOIDS
• Septic shock
• painful


ISCHEMIA/INFARCTION
HEMORRHAGE is the main HALLMARK of ischemic bowel disease
ARTERIAL THROMBUS
ARTERIAL EMBOLISM
VENOUS THROMBUS
CHF, SHOCK
INFILTRATIVE, MECHANICAL

MUCOSAL  TRANSMURAL

Ischemic Bowel Disease
Arterial (85%) Vs. venous (15%)
Oclusive or non- oclusive

Acute (severe atherosclerosis, Ar. thrombosis)

chronic hypoperfusion (watershed zones, splenic flexure), (cardiac failure, shock, dehydration, or vasoconstrictive drugs, vasculitis), Low flow.
Miscellaneous: RTx, Volvolus, Herniation, truma

Effect:

Severity of vascular involvement
Ac or ch.
The vessels affected

• Ischemic Bowel Disease

Mucosal
Mural infarction
Mucosal, Mural infarction or Transmural infarction
Intestinal responses to ischemia
in 2 phases
1. Hypoxia
2.Rreperfusion injury

• ISCHEMIA/INFARCTION

Bowel infarction

Hemorrhoids

Diletation of anal & perianal col. Ves. That connect portal & syst veins.

External Vs. internal hemorrhoids

Complication;

C.P.

Rx

Internal Hemorrhoids

External Hemorrhoids
• Constipation
• Pregnancy
• Portal hypertension

Diarrheal Dis

Diarrhea
Steatorrhea
Dysentery

Cystic Fibrosis

GLUTEN-SENSITIVE ENTEROPATHY
Sensitivity to GLUTEN, protein
in wheat oat, barley, rye
Progressive mucosal “atrophy”,
i.e. villous flattening
Relieved by gluten withdrawal
class II HLA-DQ2 or HLA-DQ8
with other immune diseases.
Both histologic and serologic findings is most specific for diagnosis of celiac disease.

Antigliadin (IgG or IgA) Abs

Endomysial (IgA) Abs
Anti -tissue transglutaminase (tTG) Abs.

Ig A Anti endomysial

Ig G if Ig A is deficient
tTG more accurate (screening test).

Clinical Features

Adults, celiac disease 30 and 60 Year
silent celiac disease,
anemia (due to iron deficiency, less, B12 and folate deficiency), diarrhea, bloating, and fatigue.
Pediatric celiac disease, 6 and 24 months
classic symptoms
dermatitis herpetiformis

Dermatitis Herpitiformis (DH)

T cell lymphoma,
S Int Ca.
Sq cell ca. esophagus

DIVERTICULOSIS/-ITIS

Pseudo diverticuli; (Colonic diverticuli);– composed of only mucosa on the luminal side and serosa externally
Mucosa/submucosa herniates through muscle wall
Assoc. w.:
INCREASED LUMINAL PRESSURE
AGE
LR
FIBER
Weakening of wall





Sigmoid diverticular disease. A, Stool-filled diverticula are regularly arranged. B. the outpouching of mucosa beneath the muscularis propria. C. protrusion of the mucosa and submucosa through the muscularis propria

DIVERTICULOSIS

Sigmoid colon

Asymptomatic unless complicated (infected (“diverticulitis”)), (“appendicitis” syndrome)
PERFORATE Peritonitis, local, diffuse
BLEED, silently, even fatally
OBSTRUCT
EXTREMELY EXTREMELY COMMON
NOT assoc w. neoplasm
Diverticulosis

Meckle’s Diverticulum

Congenital diverticulum of the distal small bowel.
2 feet from the ileocecal valve.
2 inches in size.
Twice as common in males

Meckel diverticulum,

infant or child, with painless rectal bleeding.
ileum, within 2 feet of the ileocecal valve,
present in 2% of normal persons.
results from failure of the vitelline duct to close and is found on the antimesenteric border of the intestine.
Heterotopic gastric or pancreatic tissue may be present in about one-half of cases.
Complications include; perforation, ulceration, intestinal obstruction, intussusception, and neoplasms, including carcinoid tumors.