History of Pain: MRI
In the absence of reliable evidence, it is the opinion of this work group that an MRI of a bone or soft tissue tumor of unknown etiology should be considered, and is the preferred advanced imaging study, in patients with a complaint of pain at the site of the identified tumor.

In addition to a critical analysis of imaging studies, it is important to interview patients to determine their initial awareness of the condition, changes over time, and symptoms of presentation. Specifically, the presence or absence of pain can help determine the relative likelihood of an indolent or aggressive process. A physical exam is also necessary to determine alternative explanations for pain in the area of a bone or soft tissue lesion. It is not uncommon that unrelated symptoms due to arthritis, bursitis, and tendonitis can occur in the area of a lesion that is not the origin of the pain, but rather an incidental finding in close proximity. Therefore, pain by itself does not reliably indicate an aggressive process and a dedicated history and examination to investigate other potential causes is required.

These recommendations apply primarily to the scenario of pain that cannot be attributed to a competing explanation and is likely due to the underlying lesion. The majority of bone malignancies will cause pain, often described as unassociated with activity and present at rest and night. In the setting of a bone lesion of unknown etiology, the presence of pain suggests an active process that requires further investigation to determine the underlying biology. One moderate quality study (Barai, 2004) found that patients presenting with soft tissue tumors and reporting bone pain at distant sites of metastases reliably correlated to the presence or absence of metastatic sarcoma, which were detected by Tc99 bone scan. Among a population of patients mostly reporting bone pain, two moderate quality studies (Kotb, 2014 and Weger, 2013) found that MRI and radiographs can determine benignity of bone tumors with high accuracy but determined malignancy had a weaker association to the reference standard. Although the advanced imaging modality of choice is an MRI, an exception may be in the case of an obvious bone-forming lesion without a broken periosteal reaction on radiographs that is suggestive of an osteoid osteoma, in which case CT is the preferred imaging modality.


The Future of OrthoGuidelines


The OrthoGuidelines Process