Abstract
Neuroendocrine tumor (NET) in adenoma of the gastrointestinal tract is a rare mixed glandular-endocrine neoplasm and has uncommonly been described mostly in the colon. Histologically, this tumor is composed of a predominant proportion of benign adenomatous component and a small portion of well-differentiated NE component. Only three cases of NET in gastric adenoma have been reported in the literature. We present 4 cases of NET in gastric adenoma mimicking invasive adenocarcinoma. The NETs were 0.62 mm to 4.1 mm in size and located at the basal lamina propria, muscularis mucosa and submucosa. Histologically, NETs consisted of nests, cords, tubules, and clusters of cells that predominantly interposed between the foveolar base without disturbing the overall polyp architecture. The lesions were completely removed by endoscopic submucosal dissection in three cases and in one case, subtotal gastrectomy was performed because endoscopic biopsy was invasive adenocarcinoma. The patients’ clinical course was uneventful without an evidence of recurrence or metastasis. The recognition of NET in gastric adenoma will help avoid potential diagnostic pitfalls masquerading as invasvie adenocarcinomas posed by their infiltrative pattern into submucosa.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1688552293761001
Highlights
Localized endocrine cell differentiation in benign or malignant glandular neoplasms of the gastrointestinal tract is relatively common, truely mixed glandularendocrine neoplasms are rare
The histologic spectrum ranges from amphicrine carcinoma to admixture of adenoma or adenocarcinoma with neroendocrine tumor (NET) or neuroendocrine carcinoma
We describe the clinicopathologic features of four NETs in association with gastric adenomas, to further delineate their histologic features and discuss the diagnostic pitfalls. Recognition of this rare tumor is important it can be missed due to the minute size of the lesion and it mimicks an invasive adenocarcinoma arising from adenoma, which may cause unnecessary surgery
Summary
Localized endocrine cell differentiation in benign or malignant glandular neoplasms of the gastrointestinal tract is relatively common, truely mixed glandularendocrine neoplasms are rare These tumors are composed of both glandular component like adenomas and adenocarcinomas and recognizable neuroendocrine tumor compoments. The resected segment of rectum revealed a moderately differentiated adenocarcinoma and a incidentally found, separately located 0.6 cm sized NET He received a repeat upper and lower gastrointestinal endoscopy at two year without any evidence of recurrence. The glandular components of four cases were tubular adenomas with low- and high-grade dysplasia which consisted of tubular-shaped glands lined by psuedostratified columnar epithelium with elongated hyperchromatic nuclei having coarse chromatin and occasional mitotic figures
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