Despite the advantages of FDG PET/CT, it has some drawbacks that need to be born in mind. Granulocyte colony stimulating factor (G-CSF) for BM stimulation may result in diffusely increased FDG accumulation in the BM which can cause misinterpretation as generalized marrow metastases. In addition, small metastatic lesion in the marrow can be missed due to benign bone marrow hyperplasia (such as G-CSF or presence of anemia) or inherent resolution limits of PET/CT. We found that all of our cases had increased FDG uptake in their bone marrows suggesting bone marrow involvement. FDG-PET/CT, furthermore, has a lower sensitivity in detecting sclerotic metastases seen particularly in prostate cancer probably because of hypocellularity although we did not have any case of prostate cancer to exemplify this fact . Osteoblastic metastases of breast cancer have a low or undetectable FDG uptake .