PET/CT appearance of acute pyelonephritis

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Ewing sarcoma is a rare bone cancer primarily affecting children and young adults.
• Salvage therapy is employed when standard treatments fail, often involving complex regimens like stem cell transplantation and radiation.
• Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG PET/CT) is a key imaging modality for assessing treatment response and disease progression.

Observation:

• An 18-year-old male with refractory Ewing sarcoma underwent FDG PET/CT for treatment response evaluation.
• Incidental findings included areas of increased FDG uptake (avidity) in the right kidney cortex.
• Contrast-enhanced CT revealed corresponding focal hypoenhancement in the kidney and peripheral enhancement of the right ureter.

Findings:

• The observed FDG avidity and CT findings in the kidney and ureter were consistent with acute pyelonephritis.
• This diagnosis was confirmed through clinical workup.
• The imaging successfully identified an unexpected infectious complication during oncologic surveillance.

Implications:

• FDG PET/CT can reveal unexpected infectious or inflammatory conditions beyond the primary oncologic indication.
• Radiologists and nuclear medicine physicians must be vigilant for incidental findings during oncologic imaging.
• Prompt diagnosis of complications like pyelonephritis is crucial for patient management and treatment optimization.