In children, UFPs are a rare primary cause of UPJO and more common in boys than girls. UFPs commonly appear on the left side, and the diagnosis rate is 22% before operative.5 They are often observed in the ureters, occasionally found in the renal pelvis and bladder. The ureteropelvic junction or upper ureter is the most common location where UFPs are trapped. The median size of ureteral polyps is 4.0 cm and can grow up to 17cm.2,3 In our case, the size of the ureteral polyp is only 2.0 cm. With this size, diagnosis radiologically is difficult.
The etiology of UFPs is unknown. Many experts believe the disease is congenital, found among children. However, some experts found that chronic irritation and development, such as urinary calculi, were most frequently suspected.1,2,3 Stones are the most common irritant. Most patients have renal calculi coupled with UFPs. In addition, trauma, hormonal imbalances, and other acquired factors are considered.1,2,3 UFPs are benign lesions;the recurrence rate of fibroepithelial polyps (FEPs) after resection is very low. Ludwig et al3 conducted a systematic literature review, describing clinical cases of 134 patients from 1980 to 2014. Only one patient experienced a recurrent after 1-year follow-up owing to incomplete treatment. A review of patients with ureteral polyps between 1950 and 1980 showed that none of the 108 cases had a recurrent after open resection treatment.6
No clinical symptoms are observed in the early stage of the FEPs. Although FEPs are rare and reveal a benign feature, patients with ureteral polyps can experience significant discomfort and undergo nephrectomy due to misdiagnosis. Schneider al.5 found that 17 articles published in the last decades reported 28 cases of ureteral FPs in age groups from 6 weeks to 12 years. Flank or upper abdominal pain was the principal complaint in 86% of the cases. Other symptoms include hydronephrosis, urinary tract infection, persistent proteinuria, pyuria, haematuria, etc. In our case, FEPs caused severe hydronephrosis, persistent bacteriuria, and urine-derived bacteremia, leading to persistent high fever in children, which was gradually controlled after the renal percutaneous nephrostomy. Schneider al.5 found that FEPs could cause haematuria in 3% of patients. However, Ludwig et al. 3 argued that flank pain and hematuria were the most common symptoms. In adults, hematuria is the most common symptom of malignant tumors. However, most ureteral tumors are malignant, and the proportion of benign tumors is less than 1%. Thus, preoperative diagnosis is important.
Preoperative imaging diagnosis of FEPs is difficult, but ultrasound and MRU are the most common methods for urinary tract investigations in children. Schneider5 found that the sensitivity of ultrasound, magnetic resonance imaging, and computed tomography (CT) scans for FEPs is low approximately 49% in adults. However, FEPs can be misdiagnosed as upper tract urothelial carcinoma. Intravenous urogram (IVU) and retrograde pyelography are the most ideal preoperative diagnostic methods, in which the rate can be up to 70 percent. However, a smooth filling defect is present in IVU. Enhanced CT does not provide more information than IVU. In addition, a ureteroscope is useful, and FEPs in adults can be diagnosed pathologically. However, the narrow ureter is the main obstacle to the use of ureteroscopy in children.
With limited endoscopic techniques for children and the benign nature of FEPs, pyeloplasty is the preferred treatment option for FEPs, especially for UPJ obstruction. Other treatment options are open laparoscopic or robot-assisted pyeloplasty.9,10 For patients with hydronephrosis and infection caused by ureteral polyps, active infection control is considered before surgery. since poor infection control can lead to poor anastomotic healing, causing urine leakage. In the present case, right renal percutaneous nephrostomy was performed before surgery; infection was strictly controlled, and anastomosis healed well rapidly. Thus, endoscopic resection of UFPs is a safe and it is an effective option in adults. Under the mature endoscopic technology, endoscopic resection is a minimally invasive surgical method, used as the gold standard for the treatment of ureteral polyps. Other treatment options are ureteroscopy/holmium laser lithotripsy or percutaneous nephroscopy.3,7,8,11 Meanwhile, nephrectomy is performed only when renal function is completely lost due to hydronephrosis.
UFPs are a rare primary cause of UPJO. However, UFPs should be considered when the clinical and radiographic findings of the patients are incompatible with the common etiology. Pyeloplasty is an effective treatment method for polyps in children.