Watermelon Stomach (Gastric Antral Vascular Ectasia)
Watermelon stomach, medically termed gastric antral vascular ectasia (GAVE), is an uncommon vascular lesion of the gastric antrum characterized by parallel red stripes radiating from the pylorus that resemble the stripes on a watermelon, causing chronic gastrointestinal bleeding and iron-deficiency anemia. 1, 2
Endoscopic Appearance and Diagnosis
The diagnosis is primarily based on the distinctive endoscopic appearance:
- Classic pattern: Flat or raised erythematous stripes radiating from the pylorus to the antrum in longitudinal columns along the antral folds, creating the characteristic "watermelon stripe" appearance 1, 2
- Diffuse pattern: More scattered vascular ectasias throughout the antrum, typically associated with cirrhosis rather than the classic linear pattern 2
- The lesion may be initially overlooked or misinterpreted as "gastritis" on routine endoscopy 2
Histopathologic Features
The microscopic hallmark distinguishing GAVE from other vascular lesions includes:
- Superficial fibromuscular hyperplasia of the gastric antral mucosa 3
- Capillary ectasia with dilated, tortuous vessels in the lamina propria 3
- Microvascular thrombosis 3
- Typically without significant inflammation, which helps differentiate it from inflammatory gastritis 2
Clinical Presentation
Patients present along a spectrum of bleeding severity:
- Most common: Iron-deficiency anemia secondary to chronic occult blood loss with hemoccult-positive stools 1, 2
- Moderate: Melena (dark, tarry stools) 1, 4
- Severe: Hematemesis (vomiting blood), though less common 1
- Many patients become transfusion-dependent, requiring weekly blood transfusions in severe cases 2, 4
Associated Conditions
GAVE frequently occurs in the context of systemic diseases:
- Autoimmune diseases (systemic sclerosis, CREST syndrome) 1, 2
- Liver cirrhosis - associated with the diffuse rather than classic pattern 1, 2
- Chronic renal insufficiency 1
- Cardiovascular disease 1
- The majority of patients with classic GAVE are elderly females, while the diffuse cirrhotic pattern shows no gender predominance 2
Pathophysiologic Mechanism
The bleeding mechanism involves:
- Trauma to the mucosal epithelium overlying the engorged, ectatic vessels 3
- Injury from gastric acid or intraluminal food particles 3
- The superficial location of the dilated vessels makes them vulnerable to mechanical and chemical injury 3
Common Pitfalls
- Misdiagnosis as gastritis: The endoscopic appearance may be dismissed as nonspecific inflammation rather than recognized as the specific vascular lesion of GAVE 2
- Inadequate biopsy interpretation: Pathologists must specifically look for the fibromuscular hyperplasia and vascular ectasia pattern, not just inflammation 2, 3
- Underestimating transfusion burden: Approximately 65% of patients become transfusion-dependent, requiring aggressive management 2