Menetrier's disease
Synonyms and keywords: Cystic gastritis; Giant hypertrophic gastritis; Giant mucosal hypertrophy and hyperplastic gastropathy.

# Overview
Menetrier's disease is a rare, idiopathic, premalignant disease of the mucous glands of the stomach characterized by massive gastric folds. The most commonly involved location is the fundus and corpus of the stomach. It is thought that Menetrier's disease is often due to excessive secretion of transforming growth factor alpha (TGF-). The altered gastric mucosa secretes massive amounts of mucus, resulting in low plasma protein levels (albumin) with variable degree of inflammation.

# Historical Perspective
In 1888, Pierre Menetrier, a French pathologist coined the term Menetrier's disease after describing patients with mucosal hypertrophy involving part or all of the stomach in his journal "Archives Physiologie Normale et Pathologique".

# Classification
There is no established system for the classification of Menetrier's disease.

# Pathophysiology
The exact pathogenesis of Menetrier's disease is not fully understood. However, it is thought that Menetrier's disease (in children & adults) is often due to excessive secretion of transforming growth factor alpha (TGF-). In children, Menetrier's disease is especially seen with infections such as CMV, Helicobacter pylori and herpes simplex.
- Overproduction of transforming growth factor- leads to increased signaling of the epidermal growth factor receptor (EGFR), a transmembrane receptor with tyrosine kinase activity.
- Upon activation, the EGFR activates a series of intracellular signaling pathways that leads to increased cell proliferation.
- Excessive secretion of TGF- may lead to  selective expansion of gastric foveolar cell (surface mucous cell hyperplasia) with edema, and variable degrees of inflammation. The inflammation may lead to superficial erosion of gastric mucosa or ulceration.
- Hyperplasia of gastric foveolar cells leads to enlarged gastric folds with elongated and tortuous gastric pits. In addition, there is also excessive mucus production.
- Other gastric glands such as chief or parietal cells are replaced by mucus-secreting cells leading to decreased effective gastric acid production.
- In Menetrier's disease, there is widening of gap junctions and tight junctions between cells as compared to healthy subjects, and it is believed that proteins traverse from the gastric mucosa into the gastric lumen through these widened spaces. Hence, an increase in intracellular permeability results in protein-losing enteropathy.
- In a nutshell, mucosal hyperplasia with decreased number of chief and parietal cells leads to excessive mucus production, protein loss from the stomach and subsequent hypochlorhydria or achlorhydria However, it may be noted that Menetrier's disease is typically but not always associated with protein-losing gastropathy and hypochlorhydria.
- Menetrier disease has an insidious onset with progressive features and believed to increase the risk of gastric cancer, but the magnitude of this risk is uncertain.

## Genetics
- Genes involved in the pathogenesis of Menetrier's disease include mutation in SMAD4 gene (associated with juvenile polyposis). Mutation in SMAD4 gene may lead to a mixed hypertrophic/polypoid gastropathy. A recent study showed that a dominant 1244_1247delACAG mutation of SMAD4 was identified in each of the subjects with juvenile polyposis and in Menetrier's disease.
- Overproduction of TGF- leads to overactivation of EGFR which may lead to hyperplasia of surface mucous cells.
- Some researchers suggest a unifying hypothesis which suggest TGF-SMAD4 pathway inactivation and TGF- overexpression related to Helicobacter pylori infection ultimately leads to Menetrier's disease.

## Associated conditions
- Helicobacter pylori infection
- CMV gastritis
- HIV
- Gastric cancer
- Pulmonary infections
- Thrombotic conditions
- Sclerosing cholangitis
- Ankylosing spondylitis

## Gross pathology
- Polypoid and hypertrophic gastric folds
- Large cobblestone or cerebriform gastric folds
- In rare cases, Menetrier's disease may have hyperplastic gastric polyps

## Microscopic pathology
- Decreased parietal and chief cells
- Intraepithelial lymphocytosis
- Glandular tortuosity and dilation
- Marked reduction in parietal cell number with replacement by mucous glands

# Causes
Menetrier's disease may be caused by over expression of transforming growth factor alpha (TGF-) seen especially with infections such as CMV, H.pylori and herpes simplex.

# Differentiating Menetrier's disease from Other Diseases
Menetrier's disease must be differentiated from other conditions that presents with enlarged/massive gastric folds such as Zollinger-Ellison syndrome, inflammatory gastritis, granulomatous gastritis, gastric adenomas (lymphoma/carcinoma), and hereditary conditions (such as Familial Adenomatous Polyposis).

# Epidemiology and Demographics
Menetrier's disease is seen in both children and adults. In children, Menetrier's disease affects boys and girls equally. In adults, Menetrier's disease is more commonly seen in the age group of 30 to 50 years with men four times more commonly affected than women.

# Risk Factors
Common risk factors in the development of Menetrier's disease includes overstimulation of gastric mucosa by pituitary, hypothalamic, or vagal stimuli.

# Diagnosis
- There is no established criteria for the diagnosis of Menetrier's disease. However, an endoscopic biopsy, chromium-labeled albumin test (GI protein loss), and 24-hour pH monitoring can establish the diagnosis of Menetrier's disease. Endoscopy with biopsy can identify the accurate histopathology and depict the typical gastric mucosal changes of Menetrier's disease. Biopsy is also necessary to rule out gastric carcinoma or lymphoma.
- The most accurate method to diagnose Menetrier's disease includes testing such as esophagogastroduodenoscopy with gastric pH, serum albumin and full-thickness mucosal biopsy of the involved gastric mucosa.

# History and Symptoms
Common symptoms of Menetrier's disease include epigastric pain after meals, dyspepsia, nausea and vomiting, anorexia, weight loss, and edema.

# Prognosis
In children, Menetrier's disease is usually from CMV infection and lasts for 2-14 weeks, with complete resolution being the rule. In adults, untreated Menetrier's disease may increase a patient's risk of stomach cancer. Thus, a periodic endoscopic surveillance is necessary. 

# Physical Examination
Patients with Menetrier's disease usually appear fatigued and cachexic. Common physical examination findings of patients with Menetrier's disease includes abdominal tenderness, peripheral edema and with signs of iron deficiency anemia (secondary to blood loss from ulcers) such as pallor and brittle nails. Patients with prolonged Menetrier's disease may also have ascites and abdominal distension from protein loss.

# Laboratory Findings
Laboratory findings consistent with the suggestive of Menetrier's disease include hypoalbuminemia and hypochlorhydria resulting from protein-losing enteropathy and decreased acid secretion respectively. Other tests include complete blood count and metabolic panel to determine the severity of the disease.

# X-ray
A barium meal may be helpful in the diagnosis of Menetrier's disease. Findings on an upper GI series suggestive of Menetrier's disease include thickened and lobulated gastric folds located in gastric fundus and body.

# CT scan
Abdominal CT scan may be helpful in the diagnosis of Menetrier's disease. Findings on CT scan suggestive of Menetrier's disease include massive lobulated gastric folds. An important feature of Menetrier's disease which differentiates it from gastric carcinoma includes the presence of pliable gastric folds as compared to rigid and aperistaltic gastric folds seen in carcinoma.

# Other Imaging Findings
Endoscopy may be helpful in the diagnosis of Menetrier's disease. Findings on an endoscopy suggestive of Menetrier's disease include enlarged, nodular and coarse gastric folds.

# Medical Therapy
The mainstay of therapy for Menetrier's disease is supportive care with intravenous albumin (if symptomatic) and parenteral nutritional supplementation. However, some benefit has also been observed with the use of anticholinergic drugs, acid suppression, octreotide and H. pylori eradication.

# Surgery
Surgery is not the first-line treatment option for patients with Menetrier's disease. Surgery (subtotal/total gastrectomy) is usually reserved for patients with either massive protein loss unresponsive to medical therapy or with dysplasia or carcinoma.