Introduction: In pediatric live-donor kidney transplants, there is size-mismatch between pediatric recipients and adult kidneys compared with adult transplants. This study evaluated the differences of longitudinal pathological changes between pediatric and adult transplants.
Methods: One hundred twenty-four cases who received live donor kidney transplantation between 2016 and 2020 were enrolled. In pediatric transplants (<20y/o, 35 cases, group A) and adult transplants (89 cases, group B), total 348 biopsied specimens were evaluated at posttransplant four months, one and three years using the Banff classification.
Results: In group A, recipient was 8.0±4.9 y/o, 111.7±27.2cm, 20.8±13.1kg, and donor was 42.9±10.2y/o, 166.4±9.7cm, 63.5±11.3kg (group B: recipient was 46.1±13.8 y/o, 164.5±9.9cm, 59.7±13.8kg, donor was 59.3±10.6 y/o, 160.8±8.2cm, 57.0±9.3kg, p<0.01 in all). Pre-donated Ccr (ml/min/1.73m2) were similar between both groups (group A 109.8±19.4, group B 105.4±26.4). Graft weight (g)/Recipient weight (kg) ratio in group A was significantly higher than that in group B (10.6±5.1 vs 3.0±0.9, p<0.01). The expression of urine in group B (15 min [IQR10-28.8]) was earlier than that in group A (20 min [IQR13-51], p =0.049). In acute histological change, only i score showed significant differences at posttransplant 4 months and 1 year. i score in group A was 0.15±0.36 and 0.08±0.28 at posttransplant four months and one year (group B 0.33±0.18 and 0.00±0.00). Chronic pathological changes (ct+ci scores) at posttransplant four months, one and three years were 1.09±0.98/2.03±1.56/1.56±0.94 in group A and 0.80±0.71/1.48±1.07/1.66±1.20 in group B, these scores were similar in both groups. aah scores in group B score had been increased (0.21±0.53/0.33±0.64/0.76±0.92), while group A had been low scores (0.15±0.44/0.17±0.51/0.08±0.29). Medullary ray injury at posttransplant four months, one and three years was detected in 15 cases (45.5%), 24 cases (68.6%) and 9 cases (29.1%) in group A, but 9 (10.1%) cases, 20 cases (22.5%) and 3 cases (3.8%) in group B (p<0.01 in all). The incidences of antibody-mediate rejection at posttransplant four months, one and three years did not significantly differ between both groups, and the highest incidence in group B at posttransplant three years was 12.7%. eGFR (ml/min/1.72m2) at posttransplant 4 months, 1 and 3 years in group A (79.7±19.4, 74.7±22.0, 66.5±19.0) were had been decreased, but those were significantly higher compared with group B (50.8±16.8, 47.8±14.0, 46.5±15.4, (p<0.01 in all).
Conclusions: Acute histological scores and rejection were similar between pediatric and adult transplants. Posttransplant pathological features showed medullary ray injury in pediatric transplants and hyaline changes in adult transplants.