Pembrolizumab-Induced Retroperitoneal Fibrosis Detected on 68 Ga-FAPi PET/CT

Area of Science:

• Oncology
• Immunology
• Radiology

Background:

• Hepatocellular carcinoma (HCC) is a major global cause of cancer mortality.
• Immune checkpoint inhibitors (ICIs) offer survival benefits for advanced HCC.
• ICI therapy can trigger immune-related adverse events (irAEs).

Purpose of the Study:

• To report a case of rare irAEs following ICI treatment for HCC.
• To illustrate the diagnostic utility of 68Ga-FAPi PET/CT in identifying irAEs.

Main Methods:

• Case presentation of an HCC patient experiencing abdominal pain post-pembrolizumab.
• Utilized 68Ga-FAPi PET/CT imaging for diagnostic evaluation.

Main Results:

• Imaging revealed FAPi-avid soft tissue density in the paraaortic and presacral areas.
• Diffuse FAPi uptake was observed in the thyroid gland.
• Findings were consistent with ICI-induced retroperitoneal fibrosis and thyroiditis.

Conclusions:

• Pembrolizumab can induce serious irAEs such as retroperitoneal fibrosis and thyroiditis.
• 68Ga-FAPi PET/CT is a valuable tool for diagnosing these specific irAEs in HCC patients.
• Early diagnosis and management of irAEs are crucial for patient outcomes.