Miscellaneous Topics

Heterotopic Pancreas

• Definition: Functioning pancreatic tissue located outside of its normal anatomical site.
• Prevalence: Found in 0.5% to 14% of autopsy specimens.
• Most common location: Stomach, specifically along the antral greater curvature.
• Symptoms: Patients may present with vague abdominal pain.
• Associated conditions:
  • Pancreatitis
  • Islet cell tumors
  • Pancreatic adenocarcinoma
• Diagnostic confusion:
  • Can mimic a GIST or other gastric neoplasm on endoscopy or CT.
  • Appears as small submucosal masses.
• Treatment: Surgical excision is the standard treatment.
• Diagnosis: Confirmed via pathological examination post-excision.

MCQ: Menetrier Disease

Answer: B - Acid hypersecretion and protein losing enteropathy

Explanation:

• Menetrier Disease:
  • True Features:
    • Epithelial Hyperplasia with Giant Gastric Folds: Menetrier disease is indeed associated with these changes, similar to ZES.
    • Hypochlorohydria and Protein-Losing Enteropathy: Unlike ZES, Menetrier disease is characterized by hypochlorohydria (low acid production) rather than hypersecretion. It also leads to protein-losing enteropathy.
    • Increased Risk of Gastric Cancer: There is an increased risk of developing gastric cancer in patients with Menetrier disease.
    • Cetuximab Treatment: Cetuximab, an EGFR inhibitor, is used in the treatment of Menetrier disease, particularly in cases associated with EGFR overexpression.
  • Incorrect Statement:
    • Menetrier disease does not involve acid hypersecretion but rather hypochlorohydria (low acid production).

MCQ: Dieulafoy Lesion

Answer: C - Wedge resection is the treatment of choice

Explanation:

• Dieulafoy Lesion:
  • True Features:
    • Location: Typically occurs in the proximal stomach, often within 6-10 cm of the gastroesophageal junction, generally in the fundus near the cardia.
    • Gender Predominance: More common in males, particularly in the 5th decade of life.
    • Cause: Caused by a large tortuous artery in the submucosa, which can erode and cause significant gastrointestinal bleeding.
    • Treatment: The standard approach involves endoscopic treatment, if failed then angiography, and surgery (such as wedge resection) is reserved for cases where endoscopic and angiographic methods fail.
  • Incorrect Statement:
    • Wedge resection is not the first-line treatment for Dieulafoy lesions; endoscopic management is preferred.

MCQ: Watermelon Stomach (GAVE)

Answer: A - Affects proximal stomach

Explanation:

• Gastric Antral Vascular Ectasia (GAVE) - Watermelon Stomach:
  • True Features:
    • Location: Affects the distal stomach (antrum), not the proximal stomach. This is the key distinguishing feature from portal hypertensive gastropathy (PHG), which affects the proximal stomach.
    • Demographics: Most commonly occurs in elderly patients.
    • Associations: Often associated with connective tissue diseases and chronic liver disease (CLD).
    • Estrogen Therapy: Has been used in some cases to help control blood loss associated with GAVE.
  • Incorrect Statement:
    • GAVE does not typically affect the proximal stomach; it is located in the distal stomach.

MCQ: Gastroparesis

Answer: D - Metoclopramide relieves nausea by D2 receptor antagonism by crossing the blood-brain barrier

Explanation:

• Gastroparesis:
  • True Features:
    • Gender Predominance: More commonly affects females (Mratio is approximately 1:4).
    • Glycemic Control: Improved glycemic control can help relieve symptoms of gastroparesis in diabetic patients.
    • Diagnosis: The solid phase gastric emptying scan is the diagnostic procedure of choice, rather than liquid emptying studies. A delay in gastric emptying of solids is diagnostic.
    • Treatment: Metoclopramide is the only FDA-approved drug for gastroparesis. It works by D2 receptor antagonism and has the ability to cross the blood-brain barrier, which helps relieve nausea.
  • Other Treatment Options:
    • Domperidone (another D2 antagonist with fewer central side effects) and erythromycin (a motilin receptor agonist) are also used, but not FDA-approved in the U.S. for gastroparesis.

Important Tables and Images

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Zollinger-Ellison Syndrome (ZES)

Clinical Triad:

• Gastric acid hypersecretion
• Severe Peptic Ulcer Disease (PUD)
• Gastrin-producing neuroendocrine tumors (Gastrinomas)

Key Features:

• Hypergastrinemia: The primary cause of symptoms.
• Abdominal pain and PUD: Present in over 80% of patients.
• Other symptoms: Diarrhea, weight loss, steatorrhea, esophagitis.
• Endoscopy findings: Prominent gastric rugal folds due to hypergastrinemia's trophic effects.
• Association with MEN-1: Found in 20-30% of ZES patients.

Diagnostic Evaluation:

• Fasting plasma gastrin levels:
  • Diagnostic if >1000 pg/mL.
  • Marginal elevation: If gastrin is between 200-1000 pg/mL, secretin-stimulation test may be required.
• Secretin stimulation test:
  • An increase of >200 pg/mL above basal gastrin levels is suggestive of gastrinoma.
• Exclude confounding factors: Proton Pump Inhibitors (PPIs), H. pylori infection, renal failure.

Localization & Imaging:

• Gastrinoma Triangle:
  • Points:
    • Cystic-common bile duct junction.
    • Body-neck junction of the pancreas.
    • Junction between second and third parts of the duodenum.
• Imaging techniques:
  • Triple-phase CT or MRI: Initial imaging.
  • Somatostatin receptor scintigraphy or Endoscopic Ultrasound (EUS): If primary imaging is non-diagnostic or for small lesions <1 cm or small liver metastasis.
  • if still unable to localize then surgical exploration is offered.

Treatment:

• Acid suppression:
  • High-dose PPIs: Preoperatively or for patients with metastatic/unresectable disease.
• Surgical resection:
  • Localized gastrinoma: Resection according to oncologic principles with removal of at least 10 lymph nodes.
  • Long-term cure rates: ~50%.
• Non-surgical candidates:
  • Radiation therapy: For symptom palliation or disease progression.
• Metastatic Disease:
  • Somatostatin analogs or chemotherapy (streptozocin/doxorubicin or temozolomide-based regimen).
  • Liver-directed therapies:
    • Radiofrequency ablation, cryoablation, embolization, resection, or transplantation.

MCQ: Epithelial Hyperplasia with Giant Gastric Folds and Gastric Acid Hypersecretion

Answer: C - Zollinger-Ellison Syndrome (ZES)

Explanation:

• Zollinger-Ellison Syndrome (ZES):
  • Characterized by gastric acid hypersecretion and epithelial hyperplasia with giant gastric folds due to excessive gastrin production by gastrinomas.
  • Gastrinomas stimulate the parietal cells to produce excessive amounts of acid, leading to the characteristic gastric changes.

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Stress Gastritis

Causes:

• Physical trauma, shock, sepsis, hemorrhage, respiratory failure.
• Cushing ulcers: Due to increased intracranial pressure and vagal nerve stimulation.
• Curling ulcers: Caused by thermal burns involving >30% of body surface leading to ischemia.

Pathophysiology:

• Imbalance between acid production and mucosal protection.
• Impaired mucosal defense mechanisms: Reduced blood flow, decreased mucus and bicarbonate secretion, and diminished prostaglandins.
• Stress-induced mucosal ischemia is a key factor.
• Presence of luminal acid is essential for gastritis development.

Presentation and Diagnosis:

• Develops within 1 to 2 days of a traumatic event.
• 50-75% of patients may have minimal or no symptoms.
• Painless upper GI bleeding is often the only sign.
  • May be slow and intermittent.
  • Hematemesis, hypotension, or guaiac-positive stool may occur.
• Endoscopy is required to confirm the diagnosis.

Prophylaxis:

• High-risk patients should receive prophylactic therapy.
• High-risk factors:
  • Coagulopathy.
  • Prolonged mechanical ventilation (>48 hours).
  • History of PUD, CNS injury, burn injury, or sepsis.
• Enteral nutrition reduces the risk of stress ulcer formation.
• PPIs are the preferred prophylactic agents in high-risk patients.
  • H2-receptor antagonists or sucralfate are less commonly used.
  • Prophylaxis should be limited to high-risk patients to avoid risks such as nosocomial pneumonia and C. difficile infection.

Treatment:

• Fluid resuscitation with correction of coagulation or platelet abnormalities.
• NG tube placement and IV PPI therapy.
• Urgent endoscopy to confirm diagnosis and provide initial treatment.
• Vasopressin injection or embolization for refractory bleeding.
• Surgery if bleeding causes hemodynamic instability or requires persistent transfusion:
  • Long anterior gastrotomy for proximal stomach bleeding points.
  • Truncal vagotomy and pyloroplasty may be performed to reduce acid secretion.
  • Partial gastrectomy or total gastrectomy may be required in life-threatening cases.

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