E1476. What is in Your Stomach?
  1. Meghan Moriarty; Mather Hospital; Stony Brook University Hospital
  2. Jasmine Kang; Mather Hospital
  3. Amina Farooq; Mather Hospital
  4. Robert McEvoy; Mather Hospital
  5. Islam Fayed; Mather Hospital
  6. Matthew Comito; Stony Brook University Hospital
The purpose of this study is to examine different radiologic presentations of gastric cancers (i.e. gastrointestinal stromal tumors (GIST), gastric lymphoma, carcinoid tumors, and gastric adenocarcinoma). Gastric tumors are difficult to diagnose and can often be overlooked. Additionally, many gastric lesions are found incidentally and are asymptomatic at the time of diagnosis. Imaging plays a critical role in diagnosis, biopsy planning, staging and identification of metastatic disease.

Educational Goals / Teaching Points
• Radiologic findings for GIST, gastric lymphoma, carcinoid tumors, and gastric adenocarcinoma • Best imaging modalities to use for gastric tumors • Importance of oral contrast • Features that indicate high risk of metastasis

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Gastric Adenocarcinoma: Most common gastric malignancy (>95%) with early stages demonstrating polypoid, plaque-like, or nodular mucosal and submucosal lesions. Advanced stages involve muscularis propria and beyond with lobulated or fungating polypoid lesions with possible filling defects in the dependent aspect. Nondependent walls may demonstrate a thin white layer of barium trapped between the mass and adjacent mucosa. Other findings include focal wall thickening or infiltration, gas-filled ulcers, loss of the rugal fold pattern, and rare calcifications. GIST: CT findings include exophytic areas of necrosis, generally in the upper stomach. Torricelli-Bernoulli sign demonstrates necrosis with gas formation with air rising to the top of a fluid filled cavity. Features that suggest metastasis include tumors >5cm, lobulations, heterogeneous enhancement, mesenteric fatty stranding, ulceration, exophytic growth, or lymphadenopathy. Gastric Lymphoma: CT and fluoroscopy demonstrate thickening of gastric wall with lateral extension of the tumor representing submucosal spread (Linitis Plastica sign). Gastric outlet obstruction, diffuse pronounced wall thickening, and retroperitoneal and local lymphadenopathy are common findings. Gastric Carcinoid Tumors: Type 1 tumors are typically multifocal, hypervascular, small (<1 cm) and distributed within the gastric fundus/body. Type 2 tumors are the least common (5-10%), associated with Zollinger-Ellison syndrome, and contain nodules of varied size with gastric wall thickening secondary to hypergastrinemia. Type 3 tumors are typically large solitary nodules with or without necrosis. They can have aggressive metastasis occurring in 75% of cases. Due to variable presentation, somatostatin receptor scintigraphy is often useful for metastatic detection.

Clinical presentation of gastric lesions may be difficult to differentiate solely on symptoms. Imaging is critical in identifying key features which guide tumor diagnosis and determining surgical versus medical management.