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.