Morphological markers of testicular degeneration in pediatric undescended testes: the role of fibrosis and angiodysplasia

Background. An undescended testis is associated with high risks of male infertility and tumors. Since degenerative changes in the undescended testis progress with age, studying the morphological markers of gonadal degeneration (specifically fibrosis and the state of the vascular bed) is important for understanding the pathogenesis of testicular regression and optimizing surgical tactics in children. Objective. To determine the morphological markers of testicular tissue degeneration in pediatric undescended testis and to evaluate the role of fibrosis and angiodysplasia in the progression of hypoplasia based on the study of intraoperative biopsies. Methods. A histological study of 42 biopsies of undescended testes in boys aged 1 to 17 years was conducted. The material was obtained during orchidopexy for rudimentary forms (n=31), orchiectomy for torsion (n=5), and biopsy for suspected tumor (n=6). The diameter of the seminiferous tubules, the state of the basement membrane, the number of Sertoli cells, the tubular fertility index (TFI), as well as the state of the interstitium and blood vessels were evaluated. Results. A severe degree of testicular hypoplasia was diagnosed in 76.2% of cases. Fibrosis was detected in 80.95% of the samples, and dystrophic calcification in 28.57%. Three key morphological signs of degeneration were established: 1) persistence of mesenchyme-like fibrous tissue with signs of chondroid differentiation; 2) pronounced angiodysplasia (malformed vessels, thinning or absence of muscular layers of the wall, arteriovenous anastomoses); 3) chronic inflammation (perivascular lymphohistiocytic infiltrates). The TFI value critically decreased depending on the patients' age against the background of quantitative and qualitative disorders of Leydig cells. Conclusion. Destructive changes in the germinal epithelium occur even under conditions of a mild degree of hypoplasia. The leading markers of parenchymal degeneration of the undescended testis are progressive interstitial fibrosis, the persistence of embryonic mesenchyme, and severe angiodysplasia. These processes, combined with Leydig cell dysfunction, cause a critical decrease in fertility potential and can serve as predictors of malignant transformation.