FAP is a hereditary colorectal cancer syndrome characterized by colorectal polyps and colorectal cancer.
Patients undergo surveillance colonoscopies to detect early-stage colorectal cancer and prophylactic colectomies, so the incidence of colorectal cancer has decreased. However, many patients still develop upper gastrointestinal tract malignancies. Despite regular upper endoscopic surveillance, gastric cancers are not detected in many of these patients until they are advanced or metastatic.
Patients with FAP who develop gastric cancer have gastric polyposis (more than 1 cm individual, or mounds of proximal polyps, on a background of carpet polyposis). This makes it difficult to adequately survey the entire gastric mucosa—particularly to identify gastric cancer arising within mounds of polyps. Pyloric gland adenomas, tubular adenomas, and fundic gland polyps with dysplasia have also been associated with gastric cancer.
Gautam Mankaney et al describe a case of a 60-year-old, asymptomatic woman with FAP and large mounds of proximal polyposis; cancer could not be detected by high-definition white-light and narrow-band imaging endoscopy. Biopsies taken throughout the areas of polyposis were negative for cancer or high-grade dysplasia.
Mankaney et al investigated whether EUS imaging could enhance visualization within and beneath the mounds of polyposis and identify any suspicious areas for biopsy analysis.
A 1.5-cm hypoechoic area was noted within a 4-cm thick area of polyposis. Using a 22-gauge fine needle aspiration needle, the authors obtained a tissue sample for cytology analysis, which detected malignant cells. The patient underwent a gastrectomy, pathology analyiss confirmed a 1.5-cm stage 1A gastric adenocarcinoma, consistent with the EUS findings.
Mankaney et al explain that EUS imaging is a well-established technique for evaluating the gastric wall for cancer and submucosal tumors. Gastric polyposis is limited to the superficial and deep mucosal layer. They first use a radial EUS probe in complete surveillance of the gastric mucosa. The typical endosonographic appearance of polyposis is isoechoic and homogenous. Gastric cancer, in contrast, has a hypoechoic appearance with an irregular border.