Metastatic Gastrointestinal Neuroectodermal Tumor Mimicking a Benign Hepatic Hemangioma on MRI: Role of 18F-FDG PET/CT.

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare sarcoma with limited imaging data. We report the case of a 27-year-old man with proximal jejunal GNET. During posttreatment surveillance after segmental resection and adjuvant chemotherapy, liver MRI showed a 0.8-cm caudate lobe lesion initially interpreted as a hemangioma. Eight months later, 18F-FDG PET/CT demonstrated intense focal uptake (early/delayed SUVmax: 7.54/9.13), and repeat MRI showed interval enlargement to 1.4 cm, favoring hepatic metastasis instead of hemangioma. Radiofrequency ablation was performed, and follow-up imaging studies showed no evidence of residual or recurrent disease.