Congenital mesoblastic nephroma presenting with hemorrhagic shock: An atypical and fatal presentation

Abstract

Background: Congenital mesoblastic nephroma (CMN) is the predominant primary renal neoplasm in neonates and early infancy. Histologically categorized into classic, cellular, and mixed subtypes, the classic variant typically demonstrates a benign clinical course and excellent survival rates following radical nephrectomy. Life-threatening complications are exceptionally rare. Herein, we report a fatal case of classic CMN complicated by massive spontaneous hemorrhage.

Case Presentation: A seven-month-old male infant presented to the emergency department with choking and cyanosis. Physical examination revealed marked pallor and a palpable mass in the left lower quadrant of abdomen. During observation, the patient rapidly deteriorated into hemorrhagic shock and cardiac arrest, succumbing despite resuscitative efforts. Autopsy revealed a massive left peri-nephric hematoma and a large left renal tumor. Histopathology confirmed classic CMN. Notably, a ruptured aneurysm in a lower branch of the left renal artery was identified as the source of the fatal hemorrhage.

Conclusion: While classic CMN has a typically benign clinical course, this case illustrates that it can present with catastrophic complications such as spontaneous tumor rupture and massive retroperitoneal hemorrhage. The delayed presentation (age of 7 months) and the presence of a vascular anomaly (aneurysm) likely contributed to the fatal outcome. In clinical practice, emphasis must be placed on thorough physical examinations during every routine visit. An asymptomatic abdominal mass detected in an infant is most frequently of renal origin, such as hydronephrosis, renal cysts, or benign renal neoplasms.