Nephrolithiasis is a rare condition in children. The urinary tract rupture related to stones formation or migration is atypical in children, but creates serious consequences. We present a case of a 17-year-old quadriplegic patient with neurofibromatosis type 1 and urinoma due to the rupture of calyceal fornices in the course of nephrolithiasis. The boy was admitted with symptoms of severe pneumonia complicated with sepsis and prerenal acute kidney injury. Abdominal ultrasound revealed stone casts in both renal pelvises. Antibiotics, fluid therapy and diuretics were used to improve patient's condition. On the 28th day gross hematuria was observed. The patient's condition was stable, without signs of pain or discomfort. Abdomen ultrasound showed heteroechogenic structure (125mm×100mm×100mm) localized between the lower surface of the liver and the right kidney. Contrast CT scan confirmed urinoma under the right kidney capsula. Because of the high risk of its rupture, decision of invasive evacuation of perirenal fluid was made. Using the percutaneous catheter 700ml of bloody fluid was drained. After 10 days catheter was removed without recurrence of urinoma. Concluding, in children with prolonged immobilization this condition should be taken into consideration in differential diagnosis, also special attention should be paid for accompanying scarce symptoms.