Heterogeneous osteoblastic activity in the right ischium of unclear etiology seen on NaF18-PET/CT

Abstract

We present the case of a 54 year old white male with a history of lumbar spondylolisthesis and hip arthralgia, which prompted a hip X-ray. The X-ray showed hip arthritis as well as a sclerotic lesion in the right femur concerning for possible metastasis. He was then referred for a NaF18-PET/CT bone scan to exclude metastatic bone disease. The NaF18-PET/CT study did not show evidence of osteoblastic activity in the sclerotic right femoral lesion, but showed an incidental finding of an ill-defined intense and heterogeneous osteoblastic activity affecting the entire right ischium concerning for malignancy due to the level of activity and heterogeneity. This lesion was followed up with MRI imaging. MRI imaging has been stable and the final diagnosis is favored to be chronic avulsion injury. If a case such as ours is encountered in everyday practice, the possibility of a benign traumatic etiology should be given high consideration.