Case 2. 
 Helicobacter pylori infection (gastric xanthoma) (54 y-o M)
　 　 　 　 　
　 　
Endoscopic biopsy of a xanthomatous yellow spot in the gastric mucosa
 　 　
　 　 　 　 　
　 　
Key words : 
 gastric xanthoma, Helicobacter pylori, coccoid form, chronic active gastritis 　 　
　 　 　
　
　 　 　
Localized accumulation of foamy macrophages in the inflamed lamina propria (HE) 　 H. pylori antigens seen not only on the surface but also in the foamy macrophages accumulated in the inflamed lamina propria (immunostaining)
　 　 　
　
　 　 　
Reference case 2A
H. pylori-induced chronic active gastritis.
Severe inflammation, lymphoid follicle formation and active epithelial regeneration (HE, low power)		 　 Reference case 2A
H. pylori-induced chronic active gastritis.
H. pylori colonization on the surface of regenerative epithelium (HE, higher power)
　 　 　
　
　 　 　
Reference case 2A
H. pylori-induced chronic active gastritis.
H. pylori colonized on the surface of regenerative epithelium (Warthin-Starry's silver)		 　 Reference case 2A
H. pylori-induced chronic active gastritis.
Electron micrograph of H. pylori possessing multiple flagella (negative staining).
　 　 　
　
　 　 　
Reference case 2B
H. pylori-induced chronic active gastritis.
Coccoid form of H. pylori seen on the surface of the regenerative epithelium (HE, oil immersion)		 　 Reference case 2C
H. pylori-induced gastritis and intestinal metaplasia.
The degree of inflammation is milder in intestinal metaplasia, where no HP infection is observed. Lymphoid follicles are distributed in the HP-positive non-metaplastic mucosa (HE).