The child was of Polish descent, born GV PIII on time, spontaneous delivery, Apgar 10, with a body weight of 4,040 g, and normal postnatal development. The family history revealed the death of the patient's brother on the fourth day of life; the autopsy examination showed a subcapsular hematoma of the left lobe of the liver, and kidney bleeds; the mother had had two spontaneous miscarriages. ResultsCranial ultrasound (CrUSS) and computed tomography (CT) of the head showed a focal lesion in the form of an intracerebral hematoma with a mass effect in the right frontal lobe.Basic coagulation parameters were urgently determined, showing platelet count 257.0 K/µL (N), activated partial thromboplastin time (APTT) 449.6 s (reference values: 27.2−53.3 s), prothrombin time (PT) 60.7 s (reference values: 9.1−12.1 s), prothrombin index 18.2% (reference values: 88−120%), international normalized ratio (INR) 5.71 (reference values: 0.9−1.39), and bleeding time 8 s (reference values: 4−8 s). Other laboratory test results were normal. The child had blood group 0 Rh (+).After a fresh frozen plasma (FFP) transfusion, the girl was urgently operated on; a right frontal craniotomy with the removal of the hematoma was performed. The diagnostics of coagulation disorders was extended to include the activity of coagulation factors. The first measurement was performed 48 hours after the FFP transfusion. Significantly decreased factor V (FV) activity (5.4%; reference values: 62−139%) and decreased ristocetin cofactor (vWFR:Co) activity (34.4%; reference values: 53−148%) were found.

Nephroblastoma is the most common kidney tumour in children, constitutes about 85% of cases. Although renal cell carcinoma (RCC) is the second-most common kidney malignancy in children, it constitutes only about 2–6% of all cases. Currently, the basis of children’s RCC treatment is Umbrella Protocol of SIOP-RTSG, but, due to the rare diagnosis of this neoplasm in children, in difficult cases, treatment is based on the experience in adult patients with RCC. Nephrectomy improves prognosis and is usually performed at the first step of treatment. Acute kidney injury secondary to urolithiasis in a patient after nephrectomy due to RCC is a unique, very serious complication. Study design: We present a case of a 10-year-old boy with metastatic clear cell renal cell carcinoma (ccRCC) of the right kidney and an acute renal failure of the left kidney secondary to uric acid nephrolithiasis. Partial regression of the spread of ccRCC after 12.5-month treatment with sunitinib, followed by progression being observed and satisfactory effects and tolerance of nivolumab were observed later. Comorbidity of acute kidney injury during nephrolithiasis and ccRCC after nephrectomy in children is unique. Drugs used in the treatment clear cell carcinoma in adults (sunitinib and nivolumab), are also used in children with ccRCC.