THE MORPHOGENESIS OF NONPARASITIC LIVER CYSTS

Abstract

As a result of the introduction of imaging research methods into clinical practice, the frequency of detection of cavities in the liver has significantly increased, among which nonparasitic cysts have not been sufficiently studied. The paper provides an overview of the most commonly used classifications of this pathology. Clinical and radiological manifestations of cysts were investigated based on the analysis of the results of computed tomography, magnetic resonance imaging and ultrasound sonography of 175 patients (109 with solitary cysts and 66 with polycystic liver). The tissues of the resected areas of 81 cysts and adjacent liver tissue were studied by histological and immune-histochemical methods. Various variants of liver cysts were identified: polycystic cysts, solitary cysts and the rarest variant - ciliated anterior-intestinal hepatic cysts. The morphological and histogenetic features of solitary and ciliated anterior-intestinal hepatic cysts, as well as changes in the liver tissue adjacent to the cavities, are described. Polycystic is characterized by the presence of cavities of various sizes, with thin connective tissue partitions and a lining of cubic or flattened epithelium. The lining of solitary cysts is represented by cubic, cylindrical, sometimes multi-row epithelium. Immature biliary structures in the form of von Meijenburg complexes, islets of hepatocytes, conglomerates of dysplastic vessels are revealed in their wall among the cells of connective tissue. Ciliated anterior-intestinal hepatic cysts contain components of the primary intestine wall - a lining of a cylindrical ciliated epithelium, a layer of loose connective tissue, a muscle layer, a connective tissue capsule. Morphological studies made it possible to establish violations of embryogenesis in various types of cysts. Ciliated anterior intestinal hepatic cysts develop from the anterior section of the primary intestine, while solitary cysts are derived from its middle section. Migration of the developing buds of bronchioles from the cranial part of the primary midgut into the hepatic diverticulum determines the presence of all components of the wall of the hollow organ - cylindrical ciliated epithelium, loose connective tissue, bundles of smooth muscle fibers. Simple solitary cysts are the result of abnormal remodeling of the embryonic ductal lamina, thus being a developmental abnormality of the middle section of the primary midgut. Morphological examination of the liver tissue adjacent to the walls of the cysts reveals hypoplasia of lobules, persistence of elements of the embryonic ductal plate in the form of cords and complexes of the biliary epithelium, foci of ductopenia, von Meijenburg complexes, and various variants of vascular dysplasia.