Morphological and functional changes in human skin resulted from the impact of <i>Demodex</i> mites

Abstract

   According to the latest data, up to 80 % of people in the world are carriers of Demodex mites. Light microscopy is used to detect mites during standardized superficial skin biopsy, skin scraping, etc. The study of histological preparations of the skin affected by Demodex helps analyse morphological changes in the skin structures, specify the structure and localization of insect units.   The aim of the study was to analyse the morphofunctional changes in human skin affected by Demodex mites.   Material and methods. The authors studied material from 16 male volunteers aged 26–74 years. All participants had signs of dermatitis. Pathological changes in the skin areas affected by Demodex mites and in the normal skin were analysed and compared. The study participants were punch-biopsied and then the preparations were stained with hematoxylin and eosin according to the standard technique. Skin layers were morphometrically detected, the coefficient of sclerosis of the sebaceous glands, the degree of destructive changes in the collagen fibers of the dermis and presence of leukocyte infiltration were also determined.   Results. The histological picture of the skin affected by Demodex mites demonstrated hypertrophy and destruction of the epidermis layers. The presence of “capsules” with Demodex mites and their metabolic products was manifested as hyperplasia of the epithelium and sebaceous glands. The inflammatory process caused by Demodex mites led to the formation of inflammatory mononuclear infiltration and disruption of the structure of collagen fibers, changes in the lumen of the capillaries, partial loosening of their basement membrane. In the sebaceous glands, processes of sclerosis, shape changes, hypertrophy of the walls, atrophy of sebocytes and disruption of the basement membrane were registered.   Conclusion. Demodex mites have a pronounced effect on the morphological structure of the histo-hematic barrier of the skin. This is manifested in the impaired integrity of its basement membranes, and in the pathology of the microcirculatory blood vessels. Histological preparations revealed multiple leukocyte infiltrates and thinned collagen fibers of the dermis at the sites of Demodex mites localisation.