Mesenteric Panniculitis Mimicking Metastases From Melanoma on FDG PET/CT in a Pediatric Patient Receiving

Cyrus Farazmand1, Pensiree Attaseth2, Hongming Zhuang2

  • 1Department of Radiology, Hospital of University of Pennsylvania.

Clinical Nuclear Medicine
|December 9, 2025
PubMed

Inflammatory immune-related adverse events are known complications of immunotherapy, particularly checkpoint inhibitors. A 16-year-old girl with metastatic melanoma, treated with nivolumab, dabrafenib, and trametinib, presented with abdominal pain and vomiting. Initial CT suggested metastases, showing mesenteric stranding and targetoid lesions. FDG PET/CT confirmed increased FDG uptake in the same region, but subsequent MRI and follow-up findings pointed to mesenteric panniculitis.

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