Diagnosis of chronic atrophic gastritis by morphometric image analysis. A new method to overcome the confounding effect of the inflammatory infiltrate

The risk of gastric cancer increases with the severity of gastric mucosal atrophy. Atrophy is a 'loss of properly specialized glands'. These glands may be substituted by metaplastic cells and by interstitial fibrosis, or displaced by an inflammatory infiltrate. Agreement among pathologists for the diagnosis of atrophy is poor (kappacoefficient < 0.4), probably because inflammatory infiltrate can confound the identification of gland loss. The aim of this study was to evaluate interstitial fibrosis by image analysis, and thereby overcoming the confounding effect of the inflammatory infiltrate. Gastric biopsies of 40 controls (20 children and 20 adults) and 111 patients with chronic atrophic gastritis were examined. Patients underwent another biopsy a year later. Gastric sections were examined by conventional histology (updated Sydney system) and image analysis to detect collagen and non-collagen fibres. There were no significant intra- or inter-operator differences in the evaluation by image analysis of fibre content in either controls or patients. In both controls and patients, the mean percentage of collagen fibres was lower in the gastric body (9%) than in the antrum (10%). In the antrum it was 14%, 17% and 20% in patients with mild, moderate and severe atrophy, respectively. A year later, histology showed that the grade of atrophy had decreased in 42%, probably due to the regression of inflammation, and increased in 10% of cases, but interstitial fibrosis (expressed as collagen fibre content) was practically unchanged. The use of image analysis of gastric biopsies appears to be a reliable method with which to measure interstitial fibrosis, even in the presence of an inflammatory infiltrate. This study highlights the difference between 'real gastric atrophy', where glands are replaced by collagen fibres, and 'apparent gastric atrophy', where glands are displaced by an inflammatory infiltrate.