FDG-avid sclerotic bone metastases in breast cancer patients: a PET/CT case series

Distant metastases from breast cancer most frequently occur in the skeleton. Although 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), with or without computed tomography (CT), is superior to bone scintigraphy for the detection of osteolytic bone metastases, it has been reported that sclerotic bone metastases frequently show no or only a low degree of FDG uptake on PET and PET/CT. Since both lytic and sclerotic metastases can occur in breast cancer patients, bone scintigraphy may remain of additional value in these patients. In this case series, we describe four breast cancer patients in whom FDG PET/CT has clearly visualized sclerotic bone metastases because of increased FDG uptake. Not so much the type of metastasis (sclerotic or lytic), but possibly the characteristics of the primary tumor or treatments prior to the FDG PET/CT scan might influence the degree of FDG uptake of bone metastases. The ability to detect sclerotic bone metastases based on increased FDG uptake supports the use of FDG PET/CT as a staging procedure in breast cancer patients, but knowledge of factors determining the visibility of bone metastases with FDG PET/CT is crucial.