Pathological Findings of the Antral and Pyloric Smooth Muscle in Patients with Gastroparesis-Like Syndrome Compared to Gastroparesis: Similarities and Differences.

ABSTRACT

BACKGROUND: Gastroparesis (GP)-like syndrome presents with the symptoms of GP but without delayed gastric emptying (GE). Whether GP-like syndrome is part of a spectrum of GP is not clear. This study aimed to compare the histopathological features of antral and pyloric smooth muscle tissue in GP and GP-like syndrome. METHODS: Full-thickness antral and/or pyloric biopsies were obtained from 37 GP and 18 GP-like syndrome patients who underwent abdominal surgery to place a gastric electrical stimulator or jejunal feeding tube and/or pyloroplasty. The tissues were stained with H&E, C-Kit, and trichrome. Based on previous control data, an interstitial cells of Cajal (ICC) count of <10 per high power field in the antrum and/or pylorus was considered depletion. Baseline total symptom score (TSS) was recorded. RESULTS: Twenty-four GP and 7 GP-like patients had pyloric biopsies. Pyloric ICC loss was observed in 20/24 (83.3%) GP and 2/7 (28.6%) GP-like patients (p < 0.01). Fibrosis was detected in the pyloric tissue of 20/24 (83.3%) GP and 2/7 (28.6%) GP-like patients who had pyloric trichrome staining (p < 0.01). Seventeen out of 24 (70.8%) GP patients with pyloric biopsies had concomitant pyloric ICC loss and fibrosis, while only one GP-like patient had ICC loss and simultaneous pyloric fibrosis. GP patients had a greater TSS compared to GP-like patients. In GP patients, those with pyloric ICC loss had a greater TSS compared to those with normal ICC. GP patients with pyloric fibrosis had a higher TSS compared to those without pyloric fibrosis. CONCLUSIONS: Compared to GP-like patients, the pyloric histopathological findings of ICC loss and fibrosis are common in GP and predict a greater symptom score. These pathological findings might be considered as markers of "pyloric dysfunction" and explain delayed GE in GP.