Secondary Pulmonary Hypertrophic Osteoarthropathy Detected on [68Ga]Ga-FAPI-46 PET/CT

A 55-year-old man presented with arthralgia, digital clubbing, and pitting edema. A suspicious pulmonary mass showed high tracer uptake on both [ 18 F]FDG and [ 68 Ga]Ga-FAPI-46 PET/CT. Remarkably, FAPI PET revealed a diffuse periosteal tracer uptake of the long bones, highly suggestive for hypertrophic osteoarthropathy. The secondary and paraneoplastic nature of this condition was confirmed after a biopsy of the pulmonary mass. Hypertrophic osteoarthropathy is characterized by the clinical symptoms of arthralgia, digital clubbing, and periostosis, and is associated with malignancy in 90% of cases.