False Negative Report of 18F -FDG PET/CT in a Patient with Liver Metastases due to Uveal Melanoma

To report a false negative 18F-Fluorodeoxyglucose (FDG) positron emission tomography/ computed tomography (PET/CT) of liver metastasis in a patient with malignant uveal melanoma.

A 74-year-old man with left eye uveal melanoma and liver metastasis that was found seven months after the enucleation surgery.

Seven months post-enucleation surgery, ultrasonography revealed a suspicious hepatic lesion. Further investigation using magnetic resonance imaging (MRI) and PET scan was recommended. MRI with and without contrast reported mild post-contrast enhancement in the right lobe of the liver, suggestive of metastasis from the known tumor of the patient. 18F-FDG PET/CT surprisingly showed no metabolic evidence of malignancy throughout the body. Finally, the patient was scheduled for an ultrasound-guided biopsy. Pathology reported metastatic malignant melanoma.

It is important to remember not to rely solely on PET/CT since it may report false negative results in liver metastasis.