Congenital mesoblastic nephroma presenting with massive hematuria and hemorrhagic shock

Congenital mesoblastic nephroma (CMN) is a rare benign tumor that occurs during the neonatal period and early infancy. The vast majority of these tumors present as asymptomatic palpable abdominal masses. We describe an unusual presentation of a CMN in a 10-month-old male infant who presented with massive hematuria and the development of hemorrhagic shock. Abdominal ultrasound showed a heterogeneous solid complex mass measuring 4.8 × 3.5 cm arising from the upper pole of the left kidney. The patient was resuscitated using intravenous fluids and blood transfusions because persistent massive bloody urine leading to progressive shock occurred the night of the admission day. Preoperative diagnosis was possible Wilms tumor of the left kidney. The histopathological findings were consistent with the character of a cellular variant of CMN. The patient was free of recurrence and metastasis at the 2-year follow-up examination. Our case report suggests that CMN is a rare benign renal tumor during infancy and may present with unusual massive hematuria and shock.