How large is the lesion

To answer this question (and actually measure the lesion), ensure that the full lesion is critically analyzed. Evaluating the total extent of skeletal involvement may also provide clues to any systemic alterations that relate to the diagnosis.

In general, the larger the lesion, the more likely it is to be aggressive or malignant. Conversely, smaller lesions, such as an osteoid osteoma, are usually benign. This is not universally true, of course; some very extensive lesions, such as fibrous dysplasia, may be quite large and remain benign.

The assessment of the extent skeletal involvement begins with local radiographs; Xrays of other sites or a bone scan may be needed. Generalized osteoporosis evident in the initial Xray may be a feature of diffuse bony involvement with multiple myeloma. In metastatic bone disease, other lesions may be seen in the same Xray. Besides these malignant conditions, endocrine conditions, congenital diseases (familial osteochondromatosis), or developmental skeletal dysplasia (Ollier’s disease, Maffucci’s disease) may become obvious when the skeleton surrounding the primary lesion is examined. Systemic diseases of bone, such as Paget’s disease, are often discovered by evaluating the bone peripheral to the primary lesion.

A total body bone scan is very valuable in assessing the extent of the generalized skeletal abnormality. This test will usually diagnose multiple metastases, or skeletal involvement by systemic disease (Paget’s disease), as well as demonstrate the activity of bone remodelling at the local site.

The Other Questions to Ask

• Where is the lesion?
• What is the lesion doing to the bone?
• What is the bone doing in response?
• What kind of matrix is being made?
• Is the cortex eroded?
• Is a soft tissue mass evident?