Presentation
Abdominal pain. A known case of breast cancer was operated on five years ago.
Patient Data
A right iliac bone well-defined sclerotic bony lesion with finely irregular outline.
Midline pelvic cystic lesion measures 7x8x8 cm. Right iliac bone well-defined ovoid densely sclerotic bony lesion measures 15mm with no associated aggressive features or para-osseous soft tissue masses.
The annotated image shows the attenuation measurements of this lesion, with a mean density (AV) of 1273 HU, and a maximum density of 1379 HU.
Case Discussion
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.