Histopathological Features of Helicobacter pylori Infection in Gastric Mucosa

Figures & data

Table 1 Correlation of Age and Gender with H. pylori Infection Developing to Intraepithelial Neoplasia

Stage	N (%)	Gender	Age
		Male	≤60
Stage I: mucus layer infection stage	75 (3.1)	46(61.3)	44(58.7)
Stage II: surface epithelial cells infection stage	623 (25.4)	392(62.9)	385(61.8)
Stage IIA, degeneration of surface mucous cells	332 (13.5)	207(62.3)	202(60.8)
Stage IIB, cell proliferation and transformation	291 (11.8)	185(63.6)	183(62.9)
Stage III: lamina propria lesion stage	991 (40.3)	598(60.3)	607(61.3)
Stage IIIA, acute and chronic mucosal diffuse inflammation	779 (31.7)	489(62.8)	471(60.5)
Stage IIIB, mucosal ulcer	117 (4.8)	65(55.5)	80(68.4)
Stage IIIC, mucosal lymphoid tissue hyperplasia	95 (3.9)	58(61.1)	56(58.4)
Stage IV: mucosal atrophy stage	553 (22.5)	346(62.6)	339(61.3)
Stage IVA, glandular atrophy of lamina propria	264 (10.7)	166(62.8)	165(62.5)
Stage IVB, compensatory proliferative atrophy	92 (3.7)	56(60.9)	54(58.7)
Stage IVC, intestinal metaplasia atrophy	144 (5.9)	91(63.2)	88(61.1)
Stage IVD, proliferative atrophy of smooth muscle	53 (2.2)	33(62.3)	32(60.4)
Stage V: intraepithelial neoplasia stage	215 (8.8)	133(61.9)	128(59.5)
Stage VA, low-grade intraepithelial neoplasia	153 (6.2)	92(60.1)	90(58.8)
Stage VB, high-grade intraepithelial neoplasia	62 (2.5)	41(66.1)	38(61.3)
Total	2457	1515(61.7)	1502(61.1)

Figure 1 Pathological stages of the occurrence and development of H. pylori infection in gastric mucosa.

Table 2 The Histomorphological Characteristics, Immunophenotype, and Pathological Stages of Helicobacter pylori Infection in the Gastric Mucosa from Occurrence to Intraepithelial Neoplasia

Type	Histological Characteristics	Immunophenotype
Stage I: mucus layer infection stage	Also known as the initial stage of Helicobacter pylori (Hp) infection, here, Hp colonizes in the mucus layer covered by epithelium on the surface of the gastric mucosa, and a small amount of Hp is occasionally observed on the cell membrane of the surface epithelial cells, while no Hp is present in the cytoplasm of the cells. The oval and spherical particles containing mucus, wrapped by the bounded membrane in the cytoplasm on the nucleus of the surface mucus cells, maintain intact structures.	The MUC5AC expression in the surface epithelial cells and the MUC6 expression in the cardia gland/gastric fundus gland/pyloric gland are generally normal. The positive rate of Ki-67 in the proliferative zone is 10%–15%.
Stage II: surface epithelial cells infection stage
Stage IIA: degeneration of surface mucous cells	Helicobacter pylori adheres to the cytoplasm of the surface epithelial cells, making the oval and spherical particles containing mucus that is wrapped by the bounded membrane in the cytoplasm on the nucleus of the surface mucus cells disappear, with the cytoplasm exhibiting spiderweb-like vacuolar degeneration. The cell membrane and cytoplasm are destroyed and shed to varying degrees, and the remaining cytoplasm exists as a radial structure around the nucleus. At low magnification, the formation of the characteristic Hp infection zone can be observed.	The expression of MUC5AC and MUC6 decrease slightly. The positive rate of Ki-67 in the proliferative zone is 8%–15%.
Stage IIB: cell proliferation and transformation	A large amount of Hp adheres in the cytoplasm of the surface epithelial cells, resulting in significant proliferation and transformation of the cells in the deep area of the gastric fovea, the isthmus of the gastric glands, and the proliferation area of the upper part of the gland neck; it may also develop into intraepithelial neoplasia, and, ultimately, gastric adenocarcinoma, as well as gastric foveal epithelial signet-ring cell carcinoma caused by Hp infection.	Here, CEA, CDX2, and villin can be expressed to different degrees. The positive rate of Ki-67 in the cell proliferation and transformation area is 10%–30%.
Stage III: lamina propria lesion stage
Stage IIIA: acute and chronic mucosal diffuse inflammation	Helicobacter pylori continue to adhere to the cytoplasm of the surface epithelial cells, which leads to acute and chronic diffuse inflammation of the entire lamina propria, either indirectly or reactively. The stroma of the intercellular substance is also basophilic, and a large number of infiltrated neutrophils, eosinophils, lymphocytes, and plasma cells exhibit different degrees of vacuolar degeneration. With the increase in inflammatory cells, the intercellular space widens, and the glands in the lamina propria become smaller.	The expression of MUC5AC increases and that of MUC6 decreases slightly. The positive rate of Ki-67 in the inflammation zone is 8%–15%.
Stage IIIB: mucosal ulcer	A large amount of Hp infects the surface epithelial cells, resulting in cell degeneration, necrosis, and shedding, with the necrotic cells and tissue fragments, as well as various fibrous substances, small blood vessels, and inflammatory cells forming a mucosal ulcer. One characteristic of the ulcer is that Hp can be found in the surface mucous cells and neck mucous cells in the surrounding area.	The expression of MUC5AC and MUC6 decreases to varying degrees. The positive rate of Ki-67 in the mucosal ulcer area is 8%–15%.
Stage IIIC: mucosal lymphoid tissue hyperplasia	This stage involves only a small amount of Hp-infected surface epithelial cells, as well as patch-shaped proliferating lamina propria glands (mainly significantly proliferating lymphoid tissue). Histologically, the proliferation of diffuse small lymphoid cells and hyperplasia of lymphoid follicles of different sizes can be observed, ultimately leading to the development of mucosa-associated lymphoid tissue lymphoma.	The expression of MUC5AC and MUC6 decreases to varying degrees. The positive rate of Ki-67 in the lymphoproliferative areas is 8%–15%.
Stage IV: mucosal atrophy stage
Stage IVA: glandular atrophy of lamina propria	The surface epithelial cells infected by Hp decrease, and the surface epithelial cells proliferate and transform to various degrees. The glands in the lamina propria are significantly reduced in size and number, with the number of gastric basal glands decreasing by half of the original number. The stroma increases and the glandular space widens, with the stroma mainly comprising lymphoid follicles from lymphocyte infiltration and proliferation. The number of mitotic figures is 0–1/HPF.	The MUC5AC expression is enhanced to varying degrees, while the MUC6 expression is decreased. The positive rate of Ki-67 in the atrophic area is 8%–25%.
Stage IVB: compensatory proliferative atrophy	The surface epithelial cells infected by Hp decrease or disappear, the stem cells in the proliferating zone and the cervical mucus cells proliferate, and the surface epithelial cells proliferate and form papilloma-like structures. The compensatory proliferation of surface epithelial cells is typically 0.8–1.5 mm in height. The glands of the lamina propria atrophy, are significantly reduced or disappear.	The MUC5AC expression is strongly positive, while the MUC6 expression becomes lower or disappears. The positive rate of Ki-67 in the compensatory proliferative hyperplasia area is 8%–25%.
Stage IVC: intestinal metaplasia atrophy	Intestinal metaplasia cells do not involve Hp infection, and a small amount of Hp can be found in the epithelial cells on the surface without intestinal metaplasia cells. The glands in the lamina propria atrophy or disappear, and are replaced by intestinal metaplasia glands. Intestinal metaplasia glands can occupy the entire layer of mucosa, with a width of >2 mm. Intestinal metaplasia glands have different degrees of expansion. Incomplete proliferative zones or atrophic proliferative zones can be observed at the base of the mucosa.	The MUC2 expression is positive, while the MUC5AC and MUC6 expressions decrease. The positive rate of Ki-67 in the intestinal metaplasia zone is 8%–15%.
Stage IVD: proliferative atrophy of smooth muscle	The Hp-infected surface epithelial cells decrease or disappear. Smooth muscle fibers of different sizes and shapes appear in the lamina propria, and the gastric fundus glands are separated and surrounded by these fibers. In severe cases, the smooth muscle proliferates from (and includes) the mucosal muscularis to the mucosal proliferative, forming a muscle fiberboard comprising characteristic fibrous tissue and smooth muscle. The gastric mucosal glands above the muscle fiber plate comprise proliferating stem cells, cervical mucus cells, and surface epithelial cells.	The expression of MUC5AC and MUC6 decreases in varying degrees. The positive rate of Ki-67 in the gastric mucosal gland area is 10%–30%.
Stage V: intraepithelial neoplasia stage
Stage VA: low-grade intraepithelial neoplasia	The proliferation of surface epithelial cells is papillary-shaped or exhibits a more prominent tubular structure, which can occupy almost the entire layer of the gastric mucosa. The nuclei become longer and slightly-to-moderately heteromorphic, while the nuclear chromatin increases, occupying approximately 20%–30% of the nuclei, with small to medium-sized nucleoli. A large number of lymphocytes, plasma cells, and neutrophils continue to infiltrate the intercellular substance, and lymphoid follicles can be observed at 2–4/HP. The proportion of Ki-67-positive cells is 20%–30%	The CEA, CDX2, and villin expressions are positive or weakly positive, while the Ki-67-positive rate is 15%–20%.
Stage VB: high-grade intraepithelial neoplasia	The surface mucous cells proliferate and form irregular branching structures, and the glandular epithelial cells change from columnar to cubic, with large nuclei and an increased nucleocytoplasmic ratio. The nuclei account for approximately 30%–50%, while visibly enlarged and obvious nucleoli can be observed. Milky-white spherical bodies appear in 5%–20% of the nuclei at 3–5/HPF. The proportion of Ki-67-positive cells is 30%–60%	The CEA, CDX2, and villin expressions are positive, as is the p53 expression. The proportion of Ki-67-positive cells is 30%–60%.

Figure 2 Stage I, the mucus layer infection stage: (A) Helicobacter pylori (Hp) colonizes in the mucous layer covered by the epithelium on the surface of the gastric mucosa (hematoxylin and eosin staining, ×400); (B) the result for Hp is positive (EnVision method, × 400).

Figure 3 Stage II, surface epithelial cell infection. (A) Stage IIA, the degeneration of mucus surface epithelial cells: the amount of Helicobacter pylori (Hp) bacteria is significant, and the cytoplasm exhibits spiderweb-like vacuolar degeneration; the remaining cytoplasm surrounds the nucleus in a radial pattern, while a characteristic Hp-infection band can be observed under low magnification (hematoxylin and eosin staining [H&E], ×100). (B) Stage IIB, cell proliferation and transformation: I) A large amount of Hp adheres in the cytoplasm of the surface epithelial cells, resulting in massive proliferation and transformation of the cells in the depth of the gastric pit and the isthmus of the gastric gland, as well as in the proliferative zone in the upper part of the gland neck (H&E, ×200); II) the result for Hp is positive (EnVision method, ×400).

Figure 4 Stage III, the lamina propria lesion stage. (A) Stage IIIA involves acute and chronic diffuse mucosal inflammation throughout the lamina propria, the basophilic nature of the stroma in the intercellular space enhances, and a large number of infiltrated lymphocytes, plasma cells, neutrophils, and eosinophils exhibit different degrees of vacuolar degeneration (hematoxylin and eosin [H&E] staining, × 200). (B) Stage IIIB involves mucosal ulcers, with necrotic cells and tissue debris, as well as fibrous materials, small blood vessels, and inflammatory cells constituting the ulcers (H&E staining, ×100). (C) Stage IIIC involves mucosal lymphoid hyperplasia: I) diffuse small lymphocytic hyperplasia and various lymphoid follicles of different sizes; hyperplasia of the glands is rare (H&E staining, ×100); II) the result for Helicobacter pylori is positive (EnVision method, ×100).

Figure 5 Stage IV, mucosal atrophy. (A) Stage IVA involves glandular atrophy of the lamina propria; the Helicobacter pylori-infected surface epithelial cells decrease, the surface mucus cells exhibit different degrees of proliferation and transformation, and the lamina propria glands are significantly smaller and decreased in number (hematoxylin and eosin [H&E] staining, ×200). (B) Stage IVB involves compensated proliferative atrophy; the lamina propria glands decrease or disappear and the surface epithelial cells exhibit compensatory proliferation (H&E staining, ×100). (C) Stage IVC involves intestinal metaplastic atrophy, where gland atrophy coexists with intestinal metaplasia; the glands of the intestinal metaplasia exhibit varying degrees of hyperplasia and expansion, as well as mild atypia (H&E staining, ×200). (D) Stage IVD involves smooth muscle proliferative atrophy: I) from the muscularis mucosa to the mucosal proliferation zone, proliferated smooth muscle forms a muscle fiber plate with characteristic fibrous tissue and smooth muscle together with the muscularis mucosa (H&E staining, ×200); II) the MUC6 expression is positive, exhibiting reduced glands of the fundus of the stomach (EnVision method, ×100).

Figure 6 Stage V, intraepithelial neoplasia. (A) Stage VA involves low-grade intraepithelial neoplasia, where the glands exhibit irregular branching, glandular epithelial cells are present with mild-to-moderate atypia, the basophilic nature of the cytoplasm increases, the nuclei become longer, and the neoplasia is located at the base of the glandular epithelium with infiltration of stromal lymphocytes and plasma cells (hematoxylin and eosin [H&E] staining, ×200). (B) Stage VB involves high-grade intraepithelial neoplasia: I) the irregular branching of the glands is obvious, the glandular epithelial cells change from columnar to cuboid, with large nuclei, an increased nuclear-cytoplasmic ratio, and obvious nucleoli, while the mitotic figures increase (H&E staining, ×200); II) CDX2 expression is positive (EnVision method, ×100); III) in total, 30%–60% of the cells are Ki-67 positive (EnVision method, ×100).