Abdomen / Pelvis for Friday, April 11th, 2025

History

A 10 year old male presented to the emergency department with nausea, vomiting, and abdominal pain after being hit in the abdomen while playing soccer. The patient was found to be febrile and tachycardic, with serum laboratory values showing leukocytosis and anemia. 

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Question

What is the most likely underlying diagnosis?

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Correct answer

Wilm's tumor

Discussion

A contrast-enhanced CT was performed, demonstrating a large left subcapsular hematoma (Panel A, blue arrow) compressing the kidney (Panel A, green arrow), resulting in a delayed nephrogram due to renal compression. A follow-up contrast-enhanced MRI was performed demonstrating an irregular enhancing mass along the medial aspect of the left kidney (Panel B and C, red arrow). The nonenhancing subcapsular hematoma was clearly delineated on these images (Panel B and C, blue arrow). Due to the presence of a mass, a PET CT was obtained (Panel D and E), showing intense radiolabeled glucose accumulation in the mass (blue arrows). Eight days later, the patient underwent a radical left nephroureterectomy. The specimen including the entire kidney with subcapsular hematoma and mass is seen in Panel F. At follow up the patient was stable and undergoing adjuvant chemotherapy.   

Wilms tumor is the most common pediatric renal tumor. It often presents as a palpable abdominal mass and has a heterogeneous appearance on imaging. It very rarely presents with subcapsular hematoma, and may do so in the setting of trauma as in this example. In cases of subcapsular hematoma, regardless of etiology, it is important to watch for a phenomenon called “Page kidney”. This can occur when the extrinsic mass effect on the renal parenchyma results in severe compression of the renal vasculature, activating the renin-angiotensin system and resulting in hypertension.