Enostosis versus sclerotic bone metastases is a common diagnostic dilemma in patients with known primary cancer. One study 1 has suggested that a sclerotic bone lesion can be diagnosed as a bone metastasis versus bone island if its mean attenuation is <885 HU and maximum attenuation is <1060 HU with a 95% sensitivity and a 96% specificity for both values.
Following this study, the attenuation measurements of this case lesion are highly suggestive of enostosis.