Histological changes of the esophageal mucosa in patients with achalasia

Abstract

Background. Morphological changes in the esophageal mucosa (EM) depend on the type of esophageal achalasia (ЕA). In types I and II of ЕA, morphological changes are subtle, but in types III and IV, dystrophic changes are clearly visible. ЕA can transform from one type to another. This mainly concerns the pathological transition from inflammation to fibrosis. The purpose is to investigate the histological and morphometric differences of the EM depending on the type of ЕA. Materials and methods. We studied 51 biopsy specimens of the EM in patients with ЕA. The distribution of biopsies for histo-morphometric characterisation of changes in the EM in ЕA was used according to the radiological classification of the Japanese Society of the Esophagus (2017). To study the general histological structure of the EM, biopsy sections of 5–7 μm thickness were cut using a rotary microtome RM60-ECA, stained with hematoxylin-­eosin according to the standard method, and staining for fibrosis was performed according to the Mallory-Slinchenko method. For morphometric study, the sections were photographed using a light microscope XSZ-21 (Ukraine) and measured with the Image J.45S software (USA). Results. In histological examination, the development of structural changes in the EM on the background of ЕA in 24.1 % of cases of type III was accompanied by migration of eosinophils into the lamina propria, and in 100 % — by epithelial atrophy. Dense lymphoplasmacytic infiltration was noted in all patients with types III and IV of ЕA, as well as in 93.3 % of patients with type II, whereas in type I of ЕA, this sign was diagnosed in 20 % of cases (p = 0.005 and p = 0.0001 compared with types II and III of ЕA). Ballooning degeneration was detected in 20 % of patients with EA type II, in 57.1 % with type III and in 100 % of patients with type IV. Fibrosis in the EM was observed only in ЕA type IV. Thickening of the basal layer of the squamous epithelium of the EM was noted in all patients with type IV ЕA and 86.2 % with type III ЕA, while in types I and II, it was observed in only 20 and 13.3 % of cases, respectively (p = 0.007 and p < 0.001 compared with type III ЕA). Expansion of the intercellular space was detected in 100 % of patients with types II, III and IV, and in only 40 % with type I (p = 0.009 and p = 0.0017 compared with types II and III ЕA). According to the morphometric study, the squamous epithelial height was largest in type IV ЕA — 343.40 μm versus 325.45 μm in type I ЕA (p = 0.028). The height of the basal layer was the lo­west in type II ЕA (about 40 µm) and the largest in type IV ЕA (about 50 µm) (p = 0.074). An increase in the intercellular space by 41.6 % was noted with the progression of ЕA (p = 0.001). The height of the papillae is the lowest in type II ЕA — 125.05 μm and the largest in type IV ЕA — 134.70 μm (p = 0.006). Conclusions. All types of AE are accompanied by esophagitis, histological examination of which revealed an increase in the height of the basal layer, papillae height, expansion of the intercellular space, balloon degeneration, fibrous changes in the lamina propria, lymphoplasmacytic and eosinophilic infiltration of the EM that progress depending on the type of ЕA. Morphometric studies of the EM in terms of increasing the height of the epithelium (p = 0.028), the height of the papillae (p = 0.006), the height of the basal layer (p = 0.074), and the expansion of the intercellular space (p = 0.001) allow to detect the type of ЕA.