Gastrointestinal symptoms are among the most common in SM,
with up to 80% of patients experiencing them regularly. When averaging figures from many studies,
about 51% of SM patients have abdominal pain, 43% have diarrhea, and 28% have
nausea and vomiting. 11% of SM patients
have GI bleeding, usually in the upper tract.
Other GI problems common in SM include steatorrhea (excess fat in the
stool), malabsorption, swollen liver, swollen spleen, free fluid in the abdomen
and portal hypertension. GI distress in
SM can be severe and often mimics Irritable Bowel Disease or Zollinger-Ellison
Syndrome.
Abdominal pain in SM generally has two types. The first is epigastric dyspeptic pain, found
in the upper abdomen, and is associated with ulcer disease and oversecretion of
stomach acid. Despite early reports that
peptic ulcer disease is rare in SM patients, more recent studies have
repeatedly disproven this idea. On
average, about 23% of SM patients have peptic ulcer disease. Ulcers in SM patients with dyspeptic pain are
often found on endoscopy. In one study,
19% had a duodenal ulcer, while 25% had severe duodenitis.
The other type of GI pain is characterized by lower
abdominal cramping. Generally, one type
is more prominent in a patient than the other, and they rarely co-occur with
equal intensity.
85-100% of SM patients demonstrate increased histamine
production. Histamine is known to
stimulate acid secretion, so SM patients are generally expectly to produce too much
acid in the stomach. However, studies
have shown a variety of conflicting results.
Some patients produce too much acid, some too little, and some in the
normal range. For those who overproduce
acid, the levels can be extremely high, comparable to levels seen in
Zollinger-Ellison Syndrome.
Occasionally, achlorhydria, the absence of gastric acid, has
been found in SM patients. This is
thought to be due to atrophic gastritis (chronic inflammation of the stomach
mucosa) that leads to impaired signaling from the local cells; however, this is
unproven.
Multiple studies have attempted to link serum histamine
levels with normal basal acid secretion.
In one study, all patients had high serum histamine, but 56% had normal
basal acid secretion. This finding can
be attributed to several things, including measured histamine not being fully
biologically active; circulating histamine level being less important to acid
secretion rate than the level of histamine in the local mucosa. High histamine has been found in the gastric
mucosa of several SM patients with dyspeptic pain.
Furthermore, the authors elaborated that the histamine
levels might not have been high enough to stimulate acid production; that the
H2 receptors on acid producing (parietal) cells may have become desensitized to
such high histamine levels; or that parietal cells were unable to respond to
the histamine signaling, for some other reason.
Of these possible explanations, desensitization is supported by previous
research, though not in SM patients.
In a study of 21 patients, 30% of them showed abnormalities
on upper GI barium studies. 19% had
gastric nodules and 11% had gastritis or peptic disease. Biopsies of gastric mucosa show increased
histamine and increased inflammatory cell infiltration with increased mast
cells. GI symptoms did not correlate
with mast cell counts.
Common endoscopic findings in SM patients with dyspeptic
pain include: acid hypersecretion; peptic ulcer disease; thickened gastric or
duodenal folds; nodular mucosal lesions; occasional altered motility;
occasional urticarial lesions; and increased infiltration by inflammatory cells
with or without increased mast cells.
Studies have shown that approximately 28% of SM patients have
esophageal abnormalities. These include
esophagitis, reflux, varices (abnormally enlarged veins that may bleed) or
motor uncoordination. Difficulty
swallowing was common in these patients.
When assessed, these patients showed that the lower esophageal sphincter
did not close with enough pressure.
Esophageal motor function was assessed in 16 patients by
manometry. In 15/16 patients, the
esophageal body contractions were normal.
In 62% of these patients, the lower esophageal sphincter function was
abnormal. 75% of patients had reflux
symptoms. 2/16 did not relax the
esophageal sphinter during swallowing.
Esophageal varices have been reported in several SM
patients. The current rate of occurrence
is listed as 2.5%, but this is likely an underestimation.
References:
Jensen RT. Gastrointestinal abnormalities and involvement in systemic
mastocytosis. Hematol Oncol Clin North Am. 2000;14:579–623.
Bedeir A, et al. Systemic
mastocytosis mimicking inflammatory bowel disease: A case report and discussion
of gastrointestinal pathology in systemic mastocytosis. Am J Surg Pathol. 2006 Nov;30(11): 1478-82.
Lee, Jason K, et al.
Gastrointestinal manifestations of systemic mastocytosis. World J Gastroenterol. 14(45): 7005-7008.
No comments:
Post a Comment