When you see acute inflammation in the esophagus, it is most associated with GERD whereas inflammation in the stomach cardia biopsies are associated with Helicobacter infections in the majority of cases (78-98%).
Tip-offs for Helicobacter infection
Acute and chronic inflammation (biopsy looks blue at low power)
Lymphoid aggregates (often with well formed germinal centers)
Look for organisms in the mucin-rich foci (n