Helicobacter infections with rare bacteria or minimal gastritis: Expecting the unexpected.

BACKGROUND: The routine use of special stains for detection of Helicobacter remains controversial. AIMS: To determine the frequency of histologically atypical Helicobacter infection. METHODS: All gastric biopsies received at a large pathology reference laboratory over a 6-month period were stained for Helicobacter, and the histologic and clinicopathologic parameters evaluated. RESULTS: Amongst 7663 Helicobacter-positive biopsies, 823 (10.7%) did not show typical chronic active gastritis with numerous Helicobacter organisms, and were therefore considered histologically atypical. Rare Helicobacter pylori organisms accounted for 58.0% of all atypical infections; the next most common atypical Helicobacter infection was that with minimal or no gastric inflammation (23.3% of atypical infections). Patients in these groups did not differ demographically from those with other forms of atypical or typical Helicobacter infection, although a small subgroup (6%) was more likely to have had a previously treated infection. CONCLUSIONS: In many of these atypical infections, Helicobacter would not have been suspected based on the histologic findings alone, and would have been missed without routine special stains. Performing a sensitive stain could prevent additional testing and allow prompt treatment of the affected patients, thus substantially reducing the risk for peptic ulcer and gastric cancer and preventing the transmission of the infection to family members.