Features of the morphological study of Wilms’ tumor in young children

Introduction. Wilms’ tumor (WT, syn. nephroblastoma) is the most common malignant fetal kidney tumor in children, occurring with a frequency of 0.7-0.8 cases up to 1 per 100,000 of the pediatric population. WT is characterized by a frequent combination with congenital malformations. WT may not manifest itself clinically for a long time and is often discovered accidentally by parents or during examination by a pediatrician. The pathoanatomical characteristics of WT are diverse, a wide tissue and cellular spectrum (necrosis and hemorrhage) is detected, growth into the renal and vena cava and local metastases to regional lymph nodes are often determined. Microscopically, nephroblastoma is represented by three components of varying degrees of differentiation: blastema, epithelial, and stromal components. Aim of the study: to perform a detailed macroscopic examination of the surgical material and evaluate the histological variability of the WT components. Materials and Methods. The study of a macroscopic preparation and histological sections of the tumor included 3 patients aged 1 to 6 years who were treated in the oncohematology department of the clinic of St. Petersburg State Pediatric Medical University in 2022 with a diagnosis of Wilms’ tumor. Standard techniques for preparation and staining of tumor tissues and light microscopy with photography were used. Results. Macroscopically, the size of the kidney increased due to the tumor, on the surface of a gray-pink color with areas of dark red and cyanotic, a large tuberous shape (subcapsular nodes with a tendency to protrusion) with capsule defects. On the section of the kidney, multiple nodes of inhomogeneous density were determined. In one case, the blastema type of WT was verified, in the rest - mixed type nephroblastoma. Conclusion. The macroscopic and microscopic picture of WT is extremely diverse and shows wide tissue and cellular variability (necrosis and hemorrhage). Conducting a macroscopic and histological study is a diagnostically significant method that assesses the localization of the tumor in relation to the vessels. All criteria affect the determination of the stage of the tumor and further treatment tactics.