Gastric neuroendocrine neoplasms: A review

Table 1 Classification of neuroendocrine neoplasms according to World Health Organization criteria

	Mitotic rate (mitoses/mm2)	Ki-67 index	Differentiation
Neuroendocrine tumor, Grade 1	< 2	< 3%	Well
Neuroendocrine tumor, Grade 2	2-20	3%-20%	Well
Neuroendocrine tumor, Grade 3	> 20	> 20%	Well
Neuroendocrine carcinoma, small-cell type	> 20	> 20%	Poor
Neuroendocrine carcinoma, large-cell type	> 20	> 20%	Poor
Mixed neuroendocrine–non-neuroendocrine neoplasm	Variable	Variable	Variable

Table 2 Characteristics of the subtypes of neuroendocrine neoplasms of the stomach

	Type 1	Type 2	Type 3	Type 4
Approximate Proportion	70%-80%	5%	10%-25%	Rarely
Pathogenesis	Increased gastrin levels due to atrophic gastritis. ECL origin	Increased gastrin levels due to gastrinoma. ECL origin	Not known. Mostly ECL origin	Not known. Non-ECL origin
Location and characteristics	Gastric body and fundus. Often small and multiple	Gastric body and fundus. Often small and multiple	Anywhere. Large and solitary	Anywhere. Large (often larger than type 3)
Gastrin level	Increased	Increased	Normal	Increased or normal
Prognosis	Excellent	Good	Bad	Bad
Treatment	Surveillance without resection, Endoscopic resection, surgery	Endoscopic or surgical resection, resection of gastrinoma	Gastrectomy and regional lymphadenectomy, systemic chemotherapy	Gastrectomy and regional lymphadenectomy, systemic chemotherapy