Table 3.

Histological stage classification and histological features of autoimmune gastritis

1 Early stage: may co-exist with the florid stage of AIG

(1) The ratio of the length of gastric pit to gastric gland in the fundic mucosa is almost normal, although the normal fundic gland structure (two-layered structure of parietal cell and mucous neck cell layer and chief cell layer) is obscured, and the entire gastric gland appears to be a parietal cell and mucous neck cell layer

Ratio of the length of the gastric pit and gastric gland: 1:2–4

Parietal cells: many remain in the gastric gland area, although they show degeneration (swelling = pseudohypertrophy), protrusion into the lumen, shedding, and slight decrease, accompanied by decreased proton pump staining and abnormal distribution within the cytoplasm

Chief cells (pepsinogen I positive and MUC6 negative): blurring and transformation to pyloric gland cells/mucous neck cells

Mucous neck cells (both pepsinogen I and MUC6 positive): distributed in the entire gastric glands, but marked increase at the bottom of gastric glands

Pyloric gland cells (pepsinogen I negative and MUC6 positive): (−) > (+), small number

Intestinal metaplasia (both CDX2- and CD10-positive small intestine type in the gastric body and fornix): ( −)

(2) Hyperplasia of ECL cells (chromogranin A-positive): ( −)–( +), intraductal, linear > small solid, small nodular

(3) Mild-to-moderate lymphocytic/plasma cell infiltration between the fundic glands. Lymphocytes (CD3+) are also present in the epithelium

(4) Gastrin cell hyperplasia: (+) – (−)

2 Advanced florid stage

(1) The gastric glands of the fundic mucosa are occupied by many-to-moderate numbers of mucous neck cell glands and pyloric glands. Prominent degenerated parietal cells and traces of parietal cell and mucous neck cell layer remain in some areas

Elongation of gastric pit (gastric gland pit) length and shortening of the gastric glands. Ratio of both lengths: 1: < 1 (~ 2)

Parietal cells: (−) > (+), few remaining parietal cells are degenerated, and proton pump staining is decreased/negative

Mucous neck cells: present in the lower half or bottom of the gastric glands or have disappeared

Pyloric gland cells: present in the upper part or entire length of gastric glands

Intestinal metaplasia (small intestine type): (−) to (+), mild

(2) ECL cell hyperplasia (intraductal / extraductal, linear > small solid, small nodular): (+)

(3) Gastrin cell hyperplasia: (+)

3 Advanced end stage: often co-exists with the florid stage of AIG

(1) Fundic mucosa is occupied by moderate-to-severe intestinal metaplasia and contains small amount of pyloric glands and mucous neck cell glands Alternatively, severe elongation of the gastric pit and small amount of gastric glands (pyloric glands > mucous neck cell glands) remain

(2) ECL cell hyperplasia (intraductal / extraductal, linear > small solid, small nodular): (+)

(3) Gastrin cell hyperplasia: (+)