BACKGROUND: The aim of this study was to undertake a histological evaluation of the presence of eosinophils in esophageal muscle in patients with achalasia before treatment with peroral endoscopic myotomy (POEM), with clinical follow-up at one year.

MATERIAL AND METHODS: Before treatment, esophageal biopsies including mucosa and esophageal muscle were obtained from 28 patients with achalasia. Nine patients who had undergone esophagectomy for esophageal carcinoma were included in the control group. The Eckardt Score was used to evaluate the clinical symptoms of achalasia. Histology of routinely processed tissue sections was used to perform eosinophil cell counts (0 to +++), and immunohistochemistry was used to detect expression of eosinophil major basic protein (MBP), eosinophil-derived neurotoxin (EDN), and S100 protein in cases of achalasia (n=28) and controls (n=9). The findings in patients with achalasia were compared before and one year following POEM.

RESULTS: Esophageal tissue from patients with achalasia showed eosinophils infiltrating into the muscularis externa in 85.7% (24/28), into the muscularis propria in 28.6% (8/28), and in 89% (25/28) there were few remaining myenteric ganglion cells, before POEM. The extent of inflammation was similar in all regions of the esophagus and between subtypes of achalasia. At one year following POEM, the Eckardt Scores between the former eosinophil (0) group and the eosinophil (+++) group were significantly different (Z=3.50, P=0.030).

CONCLUSIONS: Achalasia of the esophagus was associated with infiltration of the esophageal muscle by activated eosinophils and a decrease in the density of ganglion cells in the myenteric esophageal plexus.

Keywords: Eosinophils, Esophageal Achalasia, Myenteric Plexus