M. Saraga

Cysts are relatively common kidney lesions resulting from various developmental disorders during prenatal period or from other disorders during entire life. Cysts and cystic kidneys are the heterogenic group of developmental, inheritable and sporadic disorders of quite various pathogenesis. They may be single or multiple, unilateral or bilateral, diffuse, segmental or focal, microscopic or macroscopic, located at kidney cortex or at kidney medulla or both. Usually they are spherical, thin walled, epithelial-lined lesions containing fluid with chemical structure of a plasma ultrafiltrate. The kidney may be the only location of cysts or they can be connected with extrarenal cysts and other extrarenal lesions. In order to better understanding cystic kidney phenomenon it is necessary to distinct some groups of cysts and renal cystic diseases. For everyday clinical practise the differentiation between cystic dysplasias and polycistic kidney diseases is essential. They are the most frequent groups in pediatric population. Although the groups glomerulocystic kidney diseases, medullary cysts, simple renal cysts, and acquired renal cystic diseases are less frequent, they are not less important because the every single group has specific patohistologic, clinical, prognostic, and other characteristics. If the cysts and cystic kidney diseases are observed systematically it is possible to avoid misunderstandings, and to increase the effectiveness in clinical management, treatment and prognosis in the patients bearing renal cysts.