Gastritis
The understanding of gastritis has increased
markedly following elucidation of the role of H. pylori in chronic gastritis.
Type A
gastritis
This is an autoimmune condition in which there
are circulating antibodies to the parietal cell. This results in the atrophy
of the parietal cell mass, hence hypochlorhydria and ultimately achlorhydria.
As intrinsic factor is also produced by
Type B
gastritis
There are abundant epidemiological data to
support the association of this type of gastritis with H. pylori. Most commonly type B gastritis affects the antrum, and it
is these patients who are prone to peptic ulcer disease. Helicobacter-associated pangastritis is also a very common
manifestation of infection, but gastritis affecting the corpus alone does not
seem to be associated. However, there are some data to suggest that Helicobacter
may be involved in the initiation of the process. Patients with pangastritis
seem to be most prone to the development of gastric cancer.
Intestinal
metaplasia is associated with chronic pangastritis with atrophy. Although
intestinal metaplasia per se is common, intestinal metaplasia associated with
dysplasia has significant malignant potential and if this condition is
identified
the patient should be regularly screened endoscopically.
Reflux
gastritis
This is caused by enterogastric reflux and is
particularly common after gastric surgery. Its histological features are
distinct from other types of gastritis. Although commonly seen after gastric
surgery, it is occasionally found in patients with no previous surgical
intervention or who have had a cholecystectomy. Bile chelating or prokinetic
agents may be useful in treatment and as a temporising measure to avoid
consideration
of revisional surgery. Operation for the condition should be reserved for the
most severe cases.
Erosive
gastritis
This is caused by agents which disturb the
gastric mucosal barrier; NSAIDs and alcohol are common causes. The nonsteroidal-induced
gastric lesion is associated with inhibition of the cyclo-oxygenase type 1 (Cox
1) receptor enzyme, hence reducing the production of cytoprotective
prostaglandins in the stomach. Fortunately, many of the beneficial
anti-inflammatory activities of NSAIDs are mediated by Cox 2, and there is at
present much activity to produce Cox 2 inhibitors which will spare some of the
side effects of these agents.
Stress
gastritis
This is a common sequel of serious illness or
injury and is characterised by a reduction in the blood supply to superficial
mucosa of the stomach. Although common, this is not usually recognised unless
stress ulceration and bleeding supervene, in which case treatment can be
extremely difficult. The condition also sometimes follows cardiopulmonary
bypass. Prevention of the stress bleeding from the stomach is much easier than
treating it, and hence the routine use of H2 antagonists with or
without barrier agents, such as sucralfate, in patients who are on intensive
care. These measures have been shown to reduce the incidence of bleeding from
stress ulceration.
This is an unusual condition characterised by
gross hypertrophy of the gastric mucosal folds, mucus production and
hypochlorhydria. The condition is premalignant and may present with
hypoproteinaemia and anaemia. There is no treatment other than a gastrectomy.
The disease seems to be caused by overexpression of transforming growth factor
alpha (TGF-alpha). Like epidermal growth factor (EGF), this peptide also binds to
the EGF receptor. The histological features of Ménétrier’s disease may be
reproduced in transgenic mice ovetexpressing TGF-alpha (Coffey).
Lymphocytic
gastritis
This type of gastritis is seen rarely. It is
characterised by the infiltration of the gastric mucosa by T cells and is
probably associated with H. pylori infection.
Other forms of
gastritis
Eosinophilic gastritis appears to have an
allergic basis, and is treated with steroids and chromoglycate. Granulomatous
gastritis is seen rarely in Crohn’s disease and also may be associated with
tuberculosis. Acquired immunodeficiency syndrome (AIDS) gastritis is secondary
to infection with cryptospirodiosis. Phlegmonous gastritis is a rare bacterial
infection of the stomach found in patients with severe intercurrent illness. It
is usually an agonal event.