Clinical Presentation and Diagnosis

Most gastric NETs are asymptomatic. The clinical presentation of type I or II gastric carcinoids varies widely. Symptoms include vomiting, diarrhea, gastrointestinal bleeding, or intermittent gastric outlet obstruction. Carcinoid syndrome resulting from the release of histamine or bradykinin-related peptides is rare with these tumors.50 Some patients with this foregut-type carcinoid syndrome have an atypical erythematous geographic rash with minimal diarrhea. As previously mentioned, serum gastrin levels are elevated in both type I and II tumors. The gastric mucosa is atrophic in type I tumors and hyperplastic in type II tumors.46 The secretin test is negative (no increase of gastrin) in patients with type I tumors and positive in patients with type II tumors. Upper gas-

Figure 18-5. Endoscopic appearance of a gastric type II neuroendocrine tumor.

trointestinal endoscopy determines extent of disease with biopsy of tumor(s) and also of adjacent and distant gastric mucosa and assesses tumor size, number, and histology. Endoscopic ultrasonography provides information about the location and extent of submu-cosal lesions and, in type II tumors, the position of coexisting pancreatic tumors. Somatostatin scintigraphy with 111In-octreotide has a sensitivity of 75% and a specificity of 95% in localizing gastric NETs.51 This localizing study also helps determine the extent of local and rarely metastatic tumors and as a baseline study for follow-up study. Patients with type III tumors usually present like patients with gastric adenocarcinomas. However, 30 to 50% of these patients may present variations of the carcinoid syndrome including food- or alcohol-induced flushing, sweating, itching, and lacrimation.4650

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