By John Otrompke
CHICAGO -- November 12, 2009 -- Autoimmune gastritis may be twice as common as indicated in the current literature, according to a poster presented here at the American Society for Clinical Pathology (ASCP) 2009 Annual Meeting.
While the commonly estimated prevalence of the disease is only 0.1% to 0.2%, those estimates are based primarily on clinical features, not histological examination, the authors reported.
For the study, 802 randomly selected biopsies from 2007 were reviewed for chronic inflammation of the deeper part of the stomach lining, atrophy of the oxyntic glands of the stomach, and hyperplasia of the entero-chromatin-like cells.
When the biopsies were examined under a microscope, 13 cases of the autoimmune gastritis were found that had been missed by the pathologist on clinical examination, bringing the sample prevalence up to 4%.
In addition, guidelines for follow-up and surveillance of autoimmune gastritis lack specificity. "If a person is diagnosed with the disease, there aren't really concrete guidelines for surveillance," said Dr. Julianne Purdy, MD, Gastrointestinal Pathology, University of Michigan, Ann Arbor, Michigan, on October 29. "You can monitor the patient for vitamin B12 deficiency, or if they develop a tumour, you can remove any polyps, but unfortunately, some doctors do nothing."
The researchers also looked at the clinical response by healthcare providers when a case of autoimmune gastritis was diagnosed. "Because the published guidelines for endoscopy are very vague, people manage the disease differently," Dr. Purdy explained. "Did they re-scope the patient? Did they do other studies?"
Of the cases that were correctly diagnosed, 37% had at least 1 additional upper endoscopy. Serum B12 was ordered for 11 of 26 patients, parietal cell antibody for 7 of 26, intrinsic factor antibody for 4, and serum gastrin for 6.
Autoimmune gastritis develops when the oxyntic glands in the stomach are destroyed. "Since you are no longer secreting acid in the more distal stomach, you start secreting more gastrin," said Dr. Purdy. "That causes the entero-chromatin-like cells to proliferate. It just gets bigger and bigger, and can be malignant if it metastasises, but patients don't frequently get their whole stomach removed, like they do for other forms of stomach cancer. They just get periodic endoscopies."
Of the patients in the study with autoimmune gastritis, 29% presented with pain, 43% showed redness upon endoscopy, 38% had polyps or nodules, and 31% had atrophy, while 21 patients had no history relevant to autoimmune gastritis.
"Patients with autoimmune gastritis can also have anti-intrinsic factor antibody, which prevents your body from absorbing vitamin B12," Dr. Purdy added.
[Presentation title: Histologic Autoimmune Gastritis Is Frequently Unrecognized and Twice as Common as the Clinical Prevalence of the Disease. Abstract 12]
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