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Normal Duodenum

  1. The duodenum is approximately 25cm long and its configuration divides it into four parts: the duodenal bulb, and the descending, horizontal and ascending portions.
  2. In the submucosa, and peculiar to the duodenum, are Brunner's glands. These mucus-secreting glands are most numerous in the first part of the duodenum. Paneth cells and cells of the APUD system are also found within the crypts. 
  1. Duodenal Diverticula
    1. Duodenal diverticula may be acquired or congenital. Acquired or Pseudodiverticula are the product of the scarring of chronic peptic ulceration in the proximal duodenum.
    2. Most common site is the medial aspect of duodenum.
    3. Congenital examples typically arise from the second part of the duodenum; the ampulla of Vater is usually
    4. closely adjacent, and may lie within the diverticulum.
    5. Symptoms are uncommon, if present most patient present with abdominal pain or dyspepsia
    6. Investigation of choice upper G1 series,
    7. Treatment is man by medical therapy the form of antacids.
    8. Surgical treatment is required for complication or persistent symptoms.
  2. Congenital Duodenal Obstruction
    1. Congenital obstruction of the duodenum varies from a simple stenosis or diaphragm partially obstructing the lumen, to a complete block with a gap between the two ends of bowel (duodenal atresia).
    2. The site of obstruction is distal to the ampulla of Vater in about 80% of cases. Vomiting, which occurs within a few hours of birth, is of bile-stained fluid. Its common with Down's syndrome(25-33%). (Anomaly associated with down synd. are: 11 or 13 ribs, duodenal atresia / stenosis, tracheo-esophageal fistula, Hirschsprung dis )
  1. The typical double bubble' sign with absence of distal abdominal gas may be seen on abdominal radiograph (Other less common causes of the "double bubble" include annular pancreas, and peritoneal bands). Obstetric ultrasound shows polyhydramnios (in 50%).
  2. Management varies accordingly to the type of stenosis: Ladd's bands are lysed. Pure stenosis is opened longitudinally and closed transversely (Heineke-Mickulicz). Membranous stenosis is resected.
  3. Duodeno- duodenostomy is the procedure of choice for annular pancreas.
  4. Duodenojejunostomy has higher risk of long-term complications. 
  1. Intestinal Obstruction
    1. Mechanical obstruction may be
      1. Within the lumen,  
      2. Within the bowel wall,  
      3. Extrinsic (as in the case of adhesions and herniae).
    2. Causes:
      1. Postoperative adhesions can cause acute obstruction within 4 weeks;
      2. Malignant tumors (20%),
      3. Hernias (10%),
      4. Inflammatory bowel disease (5%),
      5. Volvulus (3%), 
Extra Edge:
  1. Most common cause of small intestinal obstruction is adhesions.
  2. Most common cause of large bowel obstruction neoplasm.
  3. The causes of small bowel obstruction in pediatric patients include congenital atresia, pyloric stenosis, and intussusception.
  1. Clinical Feature:
    1. If the obstruction is high, then pain and bilious vomiting with little distension will predominate;
    2. Lower small bowel obstruction is more often associated with distension and faeculent vomiting.
    3. Peristalsis may be visible in thin patients until motility becomes impaired, and examination may demonstrate the cause of the obstruction.
  2. X-ray
    1. The plain radiograph is usually confirmatory. Dilated small bowel loops with air fluid levels indicate SBO.
    2. Small bowel distension is differentiated radiologically from colonic distension by the outlining of the valvulae Uconniventes by intestinal gas, and by the distribution of distended loops, which mainly occupy the centre of the abdomen; in small bowel obstruction of mechanical cause there is usually little or no colonic gas. Absent or minimal colonic gas indicates SBO.
    3. CT scanning is sometimes indicated and may reveals both the anatomical site of obstruction and its etiology.
    4. Investigation of choice for partial small bowel obstruction is small bowel enteroclysis.
    5. Obstruction is present if the small bowel loop is greater than 2.5 cm in diameter dilated proximal to a distinct transition zone of collapsed bowel less than 1 cm in diameter. A smooth beak indicates simple obstruction without vascular compromise; a serrated beak may indicate strangulation.
  1. Small Bowel Carcinoma
    1. Adenocarcinomas of the small bowel constitute less than 2% of all gastrointestinal malignancies. The duodenum is most often affected, and 90% of carcinomas occur within 20cm of the ligament of Treitz.
    2. A number of conditions predispose to intestinal carcinoma, the most important of which are coeliac disease and familial adenomatous polyposis, Peutz-Jeghers syndrome and Crohn's disease.
    3. Presentation is usually in the 6th and 7th decades. Bleeding is common.
    4. The diagnosis may be apparent from barium studies or CT scan.
    5. Macroscopically, a polypoid pattern is commonest, and this often leads to bleeding or intussusception, but sessile, stenosing, and ulcerating tumours are also seen.
    6. The histological appearances are those of gastrointestinal adenocarcinoma.
    7. Carcinoid accounts for 40% of all the bowel malignancies.
    8. Lymphoma accounts for 15% of all the bowel malignancies .
    9. GIST is the most common mesenchymal tumor of small bowel.
    10. Adenocarcinoma is more common in duodenum and proximal jejunum.
    11. The patients usually present with dirrhoea, large amount of mucus in stool, nausea, weight loss, tenesmus.
    12. Obstruction may also be the presentation .
    13. Melena is also commonly seen, leading to the anemia.
    14. The symptoms often are related to the region involved.
    15. Periampullary carcinomas are presented as intermittent jaundice.
    16. The histopathological diagnosis gives grading of the carcinoma as well, moderately or poorly differentiated adenocarcinoma.
    17. This grading depends upon the glandular formation seen.
    18. The treatment is wide resection with anastomosis.
    19. Whipple operation is done for duodenal malignant tumors.
    20. The overall survival of the small bowel malignancy is poor even after operative procedures.

Peutz-Jeghers Syndrome

  1. Autosomal dominant condition.
  2. Multiple hamartomatous polyps occur throughout the gastrointestinal tract and are accompanied by pigmentation of the lips and buccal mucosa.
  3. Symptoms are relatively unusual, but are most likely from small bowel polyps which may bleed or cause obstruction or intussusception.
  4. Histologically, the lesions have a lobulated surface with a core of muscle fibres (derived from the muscularis mucosae) which arborizes around the crypts and mucosal glands, thinning out towards the surface.
  1. There is an associated increased risk of malignancy in the small intestine and other sites. (AIIMS Nov 09)
  1. Meckel's Diverticulum
    1. The Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, and affects approximately, 2 ft from ileocecal junction, 2inches long, 2 hetrotopic tissue and 2:1 female and male ratio..
    2. Meckel's diverticulum is a true intestinal diverticulum that results from the failure of the vitelline duct to obliterate during the fifth week of fetal development. It arises from the antemesenteric border of the ileum, 50-100cm proximal to the ileocaecal valve. It is usually about 2-5 cm in length and wide-mouthed. In approximately 50% of cases, the mucosa is ileal, but duodenal, colonic, pancreatic, and particularly gastric mucosa may be present. Ectopic tissue, found in approximately 50 percent of cases of Meckel's diverticulum, is most commonly gastric in origin, second common ectopic tissue is pancreas.
    3. Most remain asymptomatic but bleeding (Most common clinical presentation) and intestinal obstruction (Most common presentation in adult), do occur. Bleeding is usually the result of ulceration in gastric mucosa and this allows th possibility of diagnosis by scintigraphy which will usually identify tissue containing parietal cells.
    4. No diagnostic investigation is gold standard for asymptomatic MD.
    5. Diagnosis: Diagnostic Laproscopy establish the diagnosis. The diagnosis cannot be made with plain radiographs, and arteriography is not always diagnostic because arterial supply is not always abnormal.
    6. Contrast studies such as upper gastrointestinal series with small bowel follow-through are of limited value because the layers of barium-filled intestine will obstruct the view of the diverticulum. Computed tomographic scans are often nonspecific but occasionally helpful.
    7. The most useful method of detection of a Meckel's diverticulum is technetium-99m pertechnetate scanning.
    8. Complications:  
      1. Bleeding is the most common complication  
      2. Obstruction
      3. Intussusception,
      4. Diverticulitis
      5. Perforation
Extra Edge:
Intestinal obstruction is a dangerous complication, since torsion and gangrene can be fatal if early operation is not done.
  1. Treatment:
    1. A bleeding diverticulum with an indurated area in the adjacent ileum requires resection of this section of the bowel and the diverticulum.
    2. A bleeding diverticulum without ileal induration requires only resection of the diverticulum.
    3. Small, asymptomatic diverticula encountered incidentally at laparotomy need not be removed, if it is wide mouth, without any induration and attachment. Whenever a normal appendix is found during an exploration for appendicitis, Meckel's diverticulum should be suspected.
Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu Syndrome)
  1. It is an autosomal dominant condition with high penetrance.
  2. Lesions usually appear in childhood.
  3. Telangiectases are commonly found on the lips, tongue, and oral mucosa and less often on conjunctivae, ears, and digits.
  4. Lesions in the gastrointestinal mucosa often lead to a low-grade iron deficiency, and may be responsible for troublesome haemorrhage, because their number and extensive distribution throughout the intestine makes a surgical approach impractical. 
  1. Carcinoid Tumours
    1. Most common site of carcinoid tumor of bronchus.
    2. Most common site of Carcinoid tumors in GI tract is ileum.
    3. In appendix most common site of carcinoid tumor is distal 1/3 of appendix (Tip).
    4. Carcinoid are most common, neuroendocrine tumors
    5. The tumour arise from the argentaffin of Kulchitzky cells which lie deep in the crypts of Lieberkühn and are derived from neural crest tissue.
    6. Like other APUD tumours, carcinoids contain numerous neurosecretory granules.
    7. Large tumours may cause obstruction or intussusception, but symptoms are otherwise rare unless metastases to the liver are responsible for the carcinoid syndrome (seen only in 1% of cases).
    8. This syndrome is due to the excessive production of a variety of gut hormones - particularly 5-hydroxytryptamine, but also histamine, kinins, catecholamines, and prostaglandins.
    9. Typically, patients present with episodic facial flushing, watery diarrhoea, and abdominal cramps, and may have pellagra-like skin lesions as a result of niacin deficiency.
    10. Involvement of the right side of the heart is also well recognized, and there may be bronchial lesions. Auscultation may indicate pulmonary and/or tricuspid valve lesions.
    11. Pathology :-
      1. Macroscopically, the primary tumours are generally small and extra-appendiceal; and the liver may be almost completely replaced by metastases.
      2. Intestinal biopsy shows solid groups of regular polyhedral cells spreading through the submucosa and muscle; the specific neuroendocrine characteristics may be determined from immunocytochemical stains.
    12. Imaging
      1. Imaging study- For chest carcinoid – CT with scintigraphy with octreotide is investigation of choice
      2. Somatostatin receptor scintigraphs is the imaging method of choice.
      3. Single best screening test is urinary 5-HIAA.
    13. Treatment:
      1. Surgical resection is the standard curative modality. If the primary tumor is localized and resectable, 5-year survival rates are excellent (70%-90%).
      2. Radiation therapy has a minor role in patients with regionally unresectable disease and may palliate the pain of bone metastasis.
      3. Patients with carcinoid syndrome can usually be effectively palliated by injections of somatostatin analogue.
  1. Malrotation Of The Gut
    1. During embryological development, the gastrointestinal tract undertakes a series of movements, mainly during  the 6th week of intrauterine life.
    2. Rotation of the midgut occurs in an anticlockwise direction through 270°, about an axis formed by the superior mesenteric artery, which thus divides the gut into pre- and post-arterial segments.
    3. If this process is incomplete or abnormal, or if it fails completely, intestinal symptoms may result. Complete failure of rotation is uncommon and causes the post-arterial segment (the caecum and terminal ileum) to lie on the left side of the body.
    4. The duodenum then runs vertically on the right of the superior mesenteric artery, with the small intestine lying  to the right of the abdominal cavity; the ileum enters the right of the caecum. Incomplete or malrotation is commoner: the caecum is left at the splenic, or more often, at the hepatic level.
    5. Malrotation frequently causes abnormalities of fixation, which can result in neonatal volvulus, but more often it causes recurrent abdominal pain in childhood, culminating in obstruction from intestinal volvulus or fibrous bands.
    6. Up to 70% of children with intestinal malrotation also have another congenital (present at birth) malformation.
      These include the following:
      1. Abdominal wall defects and digestive system abnormalities,
        1. Gastroschisis,       
        2. Omphalocele,      
        3. Congenital diaphragmatic hernia,  
        4. Intestinal atresia,
        5. Hirschsprung’s disease,     
        6. Gastroesophageal reflux, 
        7. Intussusception,  
        8. Anorectal malformations.
      2. Cardiac abnormalities
      3. Abnormalities of the liver or spleen
    7. Treatment:
      1. Surgical repair is performed as soon as possible. The bowel is untwisted and checked carefully for damage. If the intestine is healthy, an operation called the Ladd’s procedure is performed to repair the malrotation.
      2. Since the appendix is not in its normal anatomic location, and it would be difficult to diagnose a future appendicitis, it is usually removed at this time.
  2. Intussusception
    1. It occurs when one part of bowel invaginates (intussusceptum) into an adjacent section (intussuscipiens) and results in intestinal obstruction and venous compression which if uncorrected can result in arterial insufficiency and necrosis.
    2. Peak incidence is between 5 and 10 months. More common in male infant.
    3. Most common cause of intussusceptions is idiopathic.
    4. Most common associated risk factor is hypertrophy of payers patches.
    5. Frequently occurs after a recent upper respiratory infection, by Adenovirus type 3 that causes a reactive lymphoid hyperplasia that act as lead point (of Peyer's patch).
    6. 5% are due to Meckel's diverticulum, polyps, Henoch's Schonlein purpura, hematoma, lymphoma, foreign bodies, and duplications.
    7. Commonest site involved is the ileocaecal junction
    8. Three types of intussusception can occur:
      1. Ileocolic – the small intestine invaginates into the right colon; this is the most common intussusception
      2. Ileoileal – the small intestine invaginates into itself
      3. Colocolic – the large intestine invaginates into itself most common type in adults
      4. Multiple intusscusception – rare.
      5. Retrograde intusscusception – rartest.
  1. Clinical features
    1. Intermittent colicky abdominal pain and vomiting
    2. Passage of blood - 'red currant jelly' per rectum
    3. Sausage shaped abdominal mass, Dance sign
  2. Sign in Barium study.
    1. Coiled spring sign    
    2. Claw sign
  3. Investigation of choice: USG
  1. USG finding in intussusception
    1. Bull’s eye sign
    2. Pseudo kidney sign                                                             
    3. Target sign
  1. Treatment
    1. Resuscitation with intravenous fluids and nasogastric tube
    2. Barium enema (Hydro static reduction) is option of choice for infentile age group. 
    3. In absence of peritonitis attempt reduction with air or contrast enema under radiological guidance, success rate is 80%
    4. Failure of hydrostatic reduction requires urgent operation through a right lower quadrant horizontal incision. The intussusception is reduced by push technique (Never pull) on the distal bowel like a tube of toothpaste rather than pulling the proximal bowel
    5. If push technique failed then cope method used for separation of adhesion then followed by push technique.
    6. Contraindication for hydrostatic reduction :
      1. Strangulation                        
      2. Gangrene                      
      3. Perforation    
    7. If peritonitis, shock or failed reduction requires surgery
    8. If bowel necrosis, requires resection with primary anastomosis
  1. Meconium Ileus
    1. Meconium Ileus (MI) is the earliest clinical manifestation of CF and occurs in approximately 10-15% of neonates with CF2.
    2. It occurs due to the increased viscidity of the meconium associated with its high protein and low carbohydrate content.
    3.  The most common presentation is abdominal distension with or without bilious vomiting and a failure or delay in passing meconium after birth.
    4. MI can be categorised as either simple or complicated.
      1. Complicated MI includes those with volvulus, atresia, perforation or giant cystic peritonitis.
      2. Abdominal x-ray is likely to show several loops of dilated small bowel without air-fluid levels; and possibly a soap bubble appearance in the right lower quadrant, the so-called Neuhauser sign. Complicated cases may present with greater bowel dilatation. Perforation or giant cystic meconium peritonitis intraabdominal calcifications are often noted.
      3. Un complicated may present with ground glass appearance in X-ray.
      4. Investigation of choice – Contrast enema
  • Treatment:
  1. Gastrograffin enemas (GGE) in the treatment of simple MI, Contrast agent of choice for treatment is N- acetylcysteine.
  2. All neonates with complicated and those with 2 unsuccessful GGE require operative intervention.
  3. The surgical management options of MI are varied and include :
    1. Enterotomy/appendicectomy with irrigation
    2. Enterostomy with/out resection
    3. Resection with primary anastomosis
  4. Treatment is Enterotomy and irrigation for simple MI as they had a 20% leak rate with Bishop-Koop (End-to-distal side ileal anastomosis with a distal end ileostomy which allows post-operative irrigation of the meconium pellets) or Santulli (Side-to-end anastomosis with a proximal enterostomy after resection of the dilated segment of bowel) ileostomies. 
  1. Acute Mesenteric Ischemia
    1. AMI is a syndrome in which inadequate blood flow through the mesenteric circulation causes ischemia and eventual gangrene of the bowel wall.
    2. The syndrome can be classified generally as arterial or venous disease.
    3. Arterial disease can be subdivided into nonocclusive mesenteric ischemia (NOMI) and occlusive mesenteric arterial ischemia (OMAI).
    4. Practically, AMI is divided into 4 different primary clinical entities:
      1. Acute mesenteric arterial embolus (AMAE) – It is most common cause of AMI
      2. Acute mesenteric arterial thrombosis (AMAT), NOMI,
      3. Mesenteric venous thrombosis (MVT).
      4. OMAI includes both AMAE and AMAT.
    5. Anatomy
      1. Typically the celiac artery (CA) supplies the foregut, hepatobiliary system, and spleen; the superior mesenteric artery (SMA) supplies the midgut (ie, small intestine and proximal mid colon); and the inferior mesenteric artery (IMA) supplies the hindgut (ie, distal colon and rectum. Venous drainage is through the superior mesenteric vein (SMV), which joins the portal vein.
      2. AMI arises primarily from problems in the SMA circulation or its venous outflow. Collateral circulation from the CA and IMA may allow sufficient perfusion if flow in the SMA is reduced because of occlusion, low-flow state (NOMI), or venous occlusion.
      3. Acute embolic occlusion is generally a more profound and damaging insult than thrombosis at the site of chronic disease because of the following: 
a.    Lack of protection by chronically enlarged collaterals from the other mesenteric arteries
b.    Occlusion at levels beyond the point of inflow of larger collaterals
c.    Occlusion of multiple branches to adjacent segments at the point of arterial arborization
  1. Pathophysiology:
    1. Embolic phenomena account for approximately 50% of all cases, arterial thrombosis for about 25%, NOMI for roughly 20%, and MVT for less than 10%.
    2. Hemorrhagic infarction is the common pathologic pathway whether the occlusion is arterial or venous.
    3. NOMI is precipitated by a severe reduction in mesenteric perfusion, with secondary arterial spasm from such causes as cardiac failure, septic shock, hypovolemia, or the use of potent vasopressors in patients in critical condition. 
C/F: Classical triad
  1. Severe abd pain with paucity of abdominal signs
  2. Increased GI emptying
  3. Cardiac problem.
  1. Clinical Features
    1. Nausea and vomiting are found in 75% of affected patients. Anorexia and diarrhea progressing to obstipation are also common.
    2. Of sepsis (eg, tachycardia, tachypnea, hypotension, fever, altered mental status) develop.
    3. This syndrome has a catastrophic outcome if not properly and rapidly treated.
    4. Early in the course of the disease, in the absence of peritonitis, physical signs are few and nonspecific. Tenderness is minimal to nonexistent.
    5. Stool may be guaiac positive. Peritoneal signs develop late, when infarction with necrosis or perforation occurs. Signs reflecting risk factors for AMI may be noted.
    6. Patients with embolic AMI may have atrial fibrillation or heart murmurs.
    7. Those with thrombotic AMI or NOMI may have an abdominal murmur or a scar from a
    8. recent abdominal aortic repair with or without reimplantation of the SMA. Those with MVT
    9. may have evidence of tumor, cirrhosis, DVT, or recent abdominal surgery.
  2. Lab Studies:
    1. Leukocytosis to third spacing, but it decreases with GI.
    2. Amylase levels are moderately elevated in over 50% of patients.
    3. Phosphate levels were initially thought to be sensitive, but later studies showed a sensitivity of only 25-33%.
    4. Lactate is elevated late in the clinical course. Levels that are persistently within the reference range strongly indicate a diagnosis other than AMI (sensitivity 96%, specificity 60%).
  3. Imaging Studies:
    1. Plain abdominal films
      1. Perforated viscus with free intraperitoneal air.
      2. ileus,
      3. Small bowel obstruction,
      4. Edematous/thickened bowel walls, and paucity of gas in the intestines.
      5. Pneumatosis intestinalis, ie, submucosal gas;
      6. Thumbprinting of bowel wall;
      7. Portal vein gas, are late findings.
    2. Computed tomography scan
      1. CT angiography is the investigation of choice.
      2. This technique has a sensitivity of 71% and specificity of 92%. It is not as useful as angiography, but it is noninvasive and preferred for MVT (90% sensitivity).
      3. CT scan may show pneumatosis intestinalis, portal vein gas, bowel wall and/or mesenteric edema, abnormal gas patterns, thumbprinting, and streaking of mesentery. Bowel wall edema is the most common finding on CT scan.
      4. Investigation of choice for MVT is CT- Scan
    3. Angiography –
      1. Investigation of choice of acute mesenteric arterial ischemia.
      2. Sensitivity is reported to be 88% for AMI.
      3. An embolus appears as a sharp cutoff of flow near the origin of the middle colic artery. Thrombus appears as a more tapered occlusion near the origin of the SMA.
      4. NOMI is characterized by narrowing of the origins of multiple SMA branches, alternating dilation and narrowing of the intestinal branches (ie, “string of sausages” sign), spasm of the mesenteric arcades, and impaired filling of the intramural vessels.
    4. Ultrasonography
      1. Duplex sonography studies are highly specific (92-100%) but not as sensitive (70-89%) compared to angiography. Ultrasound is considered a second-line study for AMI.
    5. Other Tests:
      1. Intraoperative fluorescein administration: During laparotomy, 1 g of fluorescein is infused. Viable bowel fluoresces brightly under a Wood lamp.
      2. ECG may show myocardial infarction or atrial fibrillation.
      1. Improve patients’ cardiovascular status.
      2. Provide oxygen at 100% or by intubation if needed.
      3. Fluid resuscitation is accomplished with isotonic sodium chloride solution, and blood products are provided as needed.
      4. Insert a nasogastric tube, and optimize cardiac status by treating arrhythmia, CHF, or myocardial infarction. Start broad-spectrum antibiotics early.
      5. Provide pain control while maintaining stable blood pressure.
    7. Angiographically infused papaverine
      1. Papaverine infused in the affected vessel is useful for all arterial forms of AMI. It relieves reactive vasospasm in occluded arterial vessels and is the only treatment for NOMI other than resection of gangrenous bowel.
    8. Angiographically infused thrombolytics
      1. Thrombolytics infused through the angiogram catheter can be a life-saving therapy for selected patients with embolic AMI.
      2. Bleeding is the main complication. Thrombolytic administration is risky and should only be undertaken if peritonitis or other signs of bowel necrosis are absent. It must be started within 8 hours of symptom onset.
      3. If symptoms do not improve within 4 hours or if peritonitis develops, stop the infusion and perform surgery.
    9. Angioplasty after thrombolysis
      1. A very select group of patients who have atherosclerotic plaques at the origin of the SMA after thrombolysis are eligible for angioplasty.
    10. Heparin for MVT
      1. Heparin anticoagulation is the main treatment for MVT.
    11. Surgical Care:
      1. Prompt laparotomy is indicated in patients with suspected AMI when expeditious angiography is not available. A second-look procedure is indicated whenever bowel of questionable viability is not resected.
      2. Preoperative care: Stabilize patients using IV fluids, antibiotics covering the colonic flora, nasogastric tube decompression, and bladder catheterization, with heparin or papaverine administered as indicated. Blood should be available.
      3. Operative care: All types of AMI may require resection of necrotic bowel if signs of peritonitis develop.
      4. Differentiation of nonviable versus viable bowel can be enhanced by intraoperative fluorescein use. Because of fat absorption, fluorescein can be used only once.
      5. Most patients can benefit from a 24- to 48-hour second-look operation to assess for viability of remaining bowel.
  1. Gastrointestinal stromal tumors
    1. Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract.
    2. GISTs are third in prevalence after adenocarcinomas and lymphomas among the histologic types of gastrointestinal tract tumors.
    3. Historically, these lesions were classified as leiomyomas or leiomyosarcomas
    4. GIST arise from interstitial cell of Cajal (C-Kit receptor of tyrosine kinase).
    5. Pathophysiology: They are submucosal lesions, which most frequently grow endophytically in parallel with the lumen of the affected structure.
    6. Most frequent site of GIST is stomach, followed by small intestine.
    7. Less frequent sites of occurrence include the colon and rectum (5-15%) and esophagus (<5%).
    8. Tumors can be classified into high- and low-risk categories based on size and mitotic activity.
    9. In GIST, the most common site of metastasis are liver & abdominal membrane (Peritoneum, mesentery, omentum)
  • Causes:
  1. Gain-of-function mutations in exon 11 of the c-kit proto-oncogene are associated with most GISTs. These mutations lead to constitutive overexpression and autophosphorylation of c-Kit, provoking a cascade of intracellular signaling that propels cells toward proliferation or away from apoptotic pathways.
  2. The c-kit proto-oncogene is located on chromosome arm 4q11-12. It encodes KIT, which is a transmembrane tyrosine kinase.
  3. A small minority of GISTs are associated with hereditary syndromes.
    1. GISTs occur with a higher than expected frequency in patients with type 1 neurofibromatosis.
    2. GISTs are also a feature of the rare Carney triad, which is observed predominantly in young women.
    3. This triad consists of epithelioid gastric stromal tumors, pulmonary chondromas, and extra-adrenal paragangliomas.
GISTs typically stain intensely for the CD117 molecule, which is an epitope of KIT. In contrast, desmoids, schwannomas (S 100–positive, KIT-negative), leiomyomas, and leiomyosarcomas (desmin-positive, KIT-negative) do not. In GISTS, according to Fletcher et al, CD117 appears diffusely in the cytoplasm in a punctate or Golgilike pattern. CD34 staining results are also positive in approximately 60% of GISTs.
  • Symptoms
  1. Vomiting,
  2. Sense of abdominal fullness
  3. Abdominal pain
Investigation of choice for GIST is Endoscopic US, though CT scan also match the efficacy of EUS investigation of choice for monitoring response to treatment is fusion scan of PET / CT.
  1. Surgery is the definitive therapy for patients with GISTs. Radical and complete surgical extirpation offers the only chance for cure.
  2. The only effective, specific, nonsurgical therapy for GISTs is imatinib mesylate (C-Kit receptor blocker). 

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