Gastric Neuroendocrine Hyperplasia, Dysplasia and Neoplasia (Carcinoid Tumors)
Definition
- Neuroendocrine cell proliferations of the stomach arise in various settings and show features ranging from hyperplasia to neoplasia
Alternate/Historical Names
- WHO 2010 has changed back to neuroendocrine cell from endocrine cell for these lesions
- Endocrine cell hyperplasia and neoplasia are equivalent terms to those used below
Diagnostic Criteria
- Gastric carcinoids and neuroendocrine cell proliferations arise in three settings
- Type A – autoimmune gastritis
- Hyperplasia, dysplasia and neoplasia are not uncommon
- Most carcinoids are <1 cm and are not aggressive
- Local metastases in 8%
- Distant metastases in 2%
- May not progress even if not resected
- Role of following is unclear
- Helicobacter infection
- Protein pump inhibitor therapy
- Type B – Zollinger Ellison syndrome with and without MEN1
- Without MEN1, generally only neuroendocrine cell hyperplasia is seen
- With MEN1, may have neuroendocrine cell dysplasia and neoplasia
- Such carcinoids may behave aggressively
- Type C – sporadic
- Frequently large and aggressive
- Over half may invade deeply and metastasize
- Types of neuroendocrine cell proliferations
- Chromogranin and/or synaptophysin stains are necessary for evaluation of neuroendocrine cells
- Normal endocrine cells
- Scattered individually, primarily in the basal crypt epithelium
- Hyperplasia
- Linear or micronodular clusters of at least 5 cells
- Micronodular clusters ≤150 microns in greatest dimension
- At least 2 linear chains / mm or 1 micronodule / mm
- Dysplasia (any of the below criteria)
- Enlargement and fusion of five or more micronodules
- >150 microns in greatest dimension
- Microinfiltration of lamina propria
- Nodule with formation of new stroma
- Neoplasia (carcinoid tumor or well differentiated neuroendocrine tumor/neoplasm)
- >0.5 mm greatest dimension
- Nodules 0.5 mm to 0.5 cm have been termed microcarcinoids
- Invasion into submucosa
- High grade / poorly differentiated neuroendocrine carcinoma is covered separately
- Gastric endocrine cell proliferations typically show features seen in other GI tract well differentiated endocrine proliferations
- Generally uniform, bland nuclei
- Occasional reports of scattered larger atypical nuclei
- Uncertain significance
- Trabecular, acinar, pseudo glandular architecture
- Variable positivity for neuroendocrine markers
- Most often serotonin
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 7/27/10, 12/28/11
