Sa1254 INFLUENCE OF AN UPFRONT ALCIAN-BLUE PERIODIC ACID SCHIFF STAIN ON THE HISTOPATHOLOGIC DIAGNOSIS OF SELECTED UPPER GASTROINTESTINAL DISORDERS

The Alcian Blue-periodic acid Schiff (ABPAS) stain at pH 2.5 is widely used in diagnostic histopathology. However, very few studies have evaluated how the use of this stain affects diagnoses in the practice of pathology. Our goal was to quantify the impact of upfront ABPAS staining on the diagnosis of selected upper gastrointestinal conditions. The study was conducted at the Gastrointestinal Division of Miraca Life Sciences, a specialized referral pathology laboratory that receives biopsy specimens from private outpatient endoscopy centers throughout the United States, and included the evaluation of three groups of patients, each of whom had upper gastrointestinal biopsies obtained during a diagnostic esophagogastroduodenoscopy (EGD). The biopsy specimens from esophagus, stomach, and duodenum underwent one of three processing and staining protocols: In group 1, specimens were internally processed and stained with hematoxylin and eosin (H&E) only; in group 2 they were processed externally (i.e., in another laboratory) and stained with H&E only; and specimens from group 3 were prepared internally and both were stained with H&E and ABPAS. Differences in the prevalence of Candida esophagitis, Barrett’s esophagus (BE), gastric intestinal metaplasia (GIM), and duodenal foveolar metaplasia were compared by unadjusted odds ratios (OR) and their 95% confidence intervals (95% CI). The study population comprised more than one million patients with esophageal, gastric, or duodenal biopsies. Candida spp. was detected more commonly in specimens stained with upfront ABPAS (2.03%) than in all those without (1.78%; OR 1.14, 95%CI 1.10-1.18). GIM was diagnosed in 10.6% of gastric specimens stained with ABPAS, but only in 8.06% of those without (OR 1.36, 95%CI 1.34-1.37). BE prevalence was lower in biopsies stained with ABPAS (12.3%) than in those with H&E only (14.3%). Duodenal foveolar metaplasia was detected in 14.4% of ABPAS-stained duodenal biopsies and in 8.5% of the H&E-stained specimens (OR 1.68, 95%CI 1.65-1.71). Control disease entities (Herpes esophagitis, Helicobacter pylori gastritis, and celiac disease) showed no significant differences between the three groups, suggesting that there is not a high level of selection bias. Upfront ABPAS stain in biopsy specimens from the upper gastrointestinal tract has a significant influence on the frequency of histopathologic diagnoses that rely on features highlighted by such a stain. While increased diagnostic yield of candidiasis and GIM using ABPAS is perhaps expected, the lower rate of BE suggests that pseudo-goblet cells may be over-interpreted when H&E is used alone.