"Epstein-Barr virus associated smooth muscle tumour as an unusual cause of ureteric graft obstruction in a child".

BACKGROUND: Epstein-Barr virus (EBV) is a DNA virus with oncogenic potential, especially in immunocompromised patients. EBV can promote smooth muscle proliferation, resulting in EBV-associated smooth muscle tumors (EBV-SMT). METHODS: We report a case of a 10-year-old child with end-stage renal disease secondary to hypoplastic crossed and fused kidneys who underwent kidney transplantation. EBV serology was unknown for the donor and negative for the recipient; three months after he had a primary EBV infection. Two years after the transplantation, percutaneous nephrostomy was performed because of a drop in the estimated glomerular filtration rate and severe dilatation of the graft. Nephrography showed contrast enhancement of the pelvis of the graft kidney and proximal ureter, with a clear blockage at the level of the mid ureter and no passage towards the bladder. A 1.5-cm tumor was found causing intraluminal compression of the mid ureter. RESULTS: Complete resection of the tumor and distal ureter was performed leaving a short proximal ureter. A tension-free uretero-ureteroanastomoses was achieved using the native ureter. There were no surgical complications. Histologic evaluation showed spindle-shaped muscle cells, moderate pleomorphism, and inflammatory infiltration. Immunohistochemical staining was positive for muscle-specific actin. Epstein-Barr encoding region (EBER) in situ hybridization was positive, confirming the diagnosis of EBV-associated SMT. CONCLUSIONS: EBV-SMT is an exceedingly rare oncological entity that may develop in either the graft or any other organ. The clinical findings are location related. EBV seroconversion following transplantation might be a risk factor for the development of SMT in solid organ recipients.

Kidney transplantation in children with CAKUT and non-CAKUT causes of chronic kidney disease: Do they have the same outcomes?

Almost half the children who undergo kidney transplantation (KTx) have congenital abnormalities of the kidney and urinary tract (CAKUT). We compared patient, graft survival, and kidney function at last follow-up between CAKUT and non-CAKUT patients after KTx. We divided the analysis into two eras: 1988-2000 and 2001-2019. Of 923 patients, 52% had CAKUT and 48% non-CAKUT chronic kidney disease (CKD). Of the latter, 341 (77%) had glomerular disease, most frequently typical HUS (32%) and primary FSGS (27%); 102 had non-glomerular disease. CAKUT patients were more often boys, younger at KTx, transplanted more frequently preemptively, but with longer time on chronic dialysis. They had less delayed graft function (DGF) and better eGFR, but higher incidence of urinary tract infection (1 year post-KTx). In both eras, 1-, 5-, and 10-year patient survival was similar in the groups, but graft survival was better in CAKUT recipients vs those with primary glomerular and primary recurrent glomerular disease: Era 1, 92.3%, 80.7%, and 63.6% vs 86.9%, 70.6%, and 49.5% (P = .02), and 76.7%, 56.6%, and 34% (P = .0003); Era 2, 96.2%, 88%, and 73.5% vs 90.3%, 76.1%, and 61% (P = .0075) and 75.4%, 54%, and 25.2% (P < .0001), respectively. Main predictors of graft loss were DGF, late acute rejection (AR), and age at KTx in CAKUT group and disease relapse, DGF, early AR, and number of HLA mismatches in recipients with glomerular disease. Graft survival was better in CAKUT patients. DGF was the main predictor of graft loss in all groups. Disease recurrence and early AR predicted graft failure in patients with glomerular disease.

Donor-specific anti-HLA antibodies in pediatric renal transplant recipients with creeping creatinine: Prevalence, histological correlations, and impact on patient and graft survival.

Donor-specific anti-HLA antibodies (DSA) causing CAMR are responsible for a high proportion of long-term graft failures after RTX. We studied the prevalence of DSA in RTX children biopsied for creeping Cr, its relationship with NA, and patient and graft survival according to histopathology. Between 2008 and 2013, 92 children were biopsied at a median of 38 months post-RTX. At biopsy, the prevalence of DSA was 49% and C4d 70%. NA rate was 45%, higher in adolescents (60%). Most frequent diagnoses were CAMR (72%) and interstitial fibrosis with tubular atrophy (IFTA) (28%). Forty-five of 66 patients with CAMR (68%) had detectable DSA. Twenty-one DSA-negative patients with CAMR had histological damage (IFTA + C4d positivity). C4d was detected in 64 of 66 biopsies with CAMR. Recipients with IFTA alone had neither C4d, nor detectable DSA, and were adherent. Graft survival at five yr was 89% in patients with CAMR, 79% in those with CAMR + TCMR Banff I, 33% in those with CAMR + TCMR Banff II, and 96% in those with IFTA. ABMR and complement activation were frequent in children biopsied for creeping Cr. Recipients with DSA were more likely to be non-adherent and have CAMR or CAMR + TCMR and worse graft survival.