We present the case of an 87-year-old man with a history of melanoma metastatic to the lungs found to have an FDG-negative liver lesion that was initially thought to be benign. Follow-up CT revealed growth of the liver lesion despite excellent response to nivolumab therapy of the pulmonary melanoma metastases. Biopsy of the lesion confirmed primary hepatocellular carcinoma. Follow-up 18F-FDG PET/CT showed minimal FDG uptake, slightly above liver background, and subsequent 68Ga-PSMA-11 PET/MR showed focal, intense uptake of radiotracer in a different region of the tumor. These imaging findings support intratumor metabolic heterogeneity with radiotracer uptake in different tumor locations.
From the Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA.
Received for publication August 6, 2018; revision accepted November 27, 2018.
Conflicts of interests and sources of funding: 68Ga PSMA PET/MR was funded by an industry research grant from GE Healthcare held by S.C.B. None declared to all other authors.
Correspondence to: Spencer C. Behr, MD, Section of Nuclear Medicine, Department of Radiology and Biomedical Imaging, 505 Parnassus Ave, M396, Box 0628 San Francisco, CA 94143. E-mail: Spencer.Behr@ucsf.edu.