Clinical Manifestations and Pathogenesis

Because granulomata can be found in the gastric mucosa of patients with infectious, inflammatory, and neoplastic diseases, as well as in otherwise healthy persons, neither clinical manifestations nor endoscopic appearances are useful to predict the presence of gastric granulomata. Thus, the stomach may be completely normal or may exhibit characteristics of the associated conditions.

Mycobacterium tuberculosis and Histoplasmacapsulatum Infection Tuberculosis is the most common cause of granulomatous disease of the gastrointestinal tract, but the stomach is rarely affected, even in the presence of severe ileocecal involvement. Primary gastric tuberculosis has been reported mostly from developing countries with a high prevalence of Mycobacterium tuberculosis infection. In almost all such cases, gastric tuberculosis was diagnosed because of the presence of a large, nonhealing gastric ulcer. A few cases of primary infection of the stomach by the dimorphic fungus Histoplasmacapsulatum have been reported. As in patients with gastric tuberculosis, these patients presented with signs and symptoms that led to the discovery of a large gastric ulcer initially interpreted clinically as malignant.

Helicobacter pylori Infection Unexplained granulomata have been found in patients with H.pylori gastritis, but this finding is extremely rare, on the order of less than 1 in 1000 infected patients. Although a role for H.pylori in the causation of granulomata has been postulated, there is no evidence to support this hypothesis.

Anisakiasis Early lesions of anisakiasis range from interstitial edema with a loose, eosinophilic inflammatory infiltrate to eosinophilic abscesses, in which well-preserved larvae are often detected. In later lesions, the most common finding is the presence of foreign body granulomata, sometimes associated with fragments of helminthic cuticles.

Foreign Bodies A common cause of gastric foreign body granulomata is suture material in patients who have undergone a partial gastrectomy. In patients with gastric ulcer, food particles may become engulfed in the ulcer crater and may cause a foreign body reaction. When such granulomata are found in biopsy specimens obtained from active ulcers, their origin is readily apparent; diagnostic difficulties may arise when granulomata are found in specimens from healed ulcers and the pathologist is unaware of the relevant clinical information.

Tumors Rarely, adenocarcinomas (particularly mucin-secreting tumors) may induce the formation of foreign body granulomata in the gastric mucosa or perigastric lymph nodes. Granulomata have also been noted in the gastric mucosa of few patients with gastric non-MALT lymphoma.

Other Unusual Causes In rare instances, granulomatous gastritis may be part of an immune-mediated vasculitis syndrome or Wegener granulomatosis. Sometimes, it may assume a form akin to xanthogranulomatouscholecystitis.

Дата добавления: 2015-11-14