Fig. 2

Typical histopathological findings of AIG-related type 1 gastric NETs. (a) Severe atrophy of the inherent glands in the gastric mucosa accompanied by intestinal metaplasia and muscularis mucosa hyperplasia, with neuroendocrine cell hyperplasia visible in the base of the gastric mucosa and muscularis mucosa (hematoxylin and eosin staining, 100×); (b) Linear and micronodule hyperplasia of neuroendocrine cells are observed at the base of the gastric mucosa and muscularis mucosa (Syn immunostaining, 200×); (c) A NET with background gastric mucosal atrophy and the presence of nodular hyperplasia of neuroendocrine cells (hematoxylin and eosin staining, 100×); (d) A NET, rich in cells and a blood supply and uniform in size, with nuclei showing “salt and pepper” chromatin and rare mitotic activity (hematoxylin and eosin staining, 400×); (e) Positive expression of CgA was observed in NET cells and neuroendocrine cells with background gastric mucosal hyperplasia (CgA immunostaining, 100×); (f) A well-differentiated G1 NET, with a Ki67 proliferation index of 1% (Ki67 immunostaining, 200×)