Bone and Soft Tissue Tumors

This issue of Seminars in Musculoskeletal Radiology focuses on the contentious issues and mistakes, that is, lessons learned, regarding bone and soft tissue tumors. It offers practical guidelines and approaches for daily work. Imaging of bone and soft tissue tumors has continued to evolve over the years, and the advancement in imaging techniques, such as diffusion-weighted imaging, Dixon, and dynamic contrast-enhanced MRI, continues to maintain our subspecialty's prominence in patient care. The interpretation of musculoskeletal (MSK) tumor imaging is often complex and challenging. Thus an organized, systematic approach is essential in differential diagnosis, therapeutic management, and the early diagnosis of treatment failure or relapse. Review of the patient's clinical and surgical history plus pretreatment imaging studies aids in the diagnosis of the latter.

This issue includes seven richly illustrated review articles that provide practicing radiologists, residents, and fellows with the most accurate and current update in this special field of MSK imaging. The authors are members of the Tumor Subcommittee of the European Society of Musculoskeletal Radiology, and the topics were discussed in several recent subcommittee meetings.

The first article, “Chondroid Tumors as an Incidental Findings,” comes from Diana Afonso, Portugal, and colleagues from Spain and the United Kingdom. It summarizes changes made to the updated 2013 World Health Organization classification and highlights the diagnostic features differentiating an enchondroma from a low-grade chondrosarcoma. The practical imaging aspects of the other chondroid tumors are also addressed.

The second article, “Practical Input on Bone Tumor Imaging,” by Magdalena Lunkiewicz and colleagues, all from Switzerland, nicely reviews the risk factors associated with impending fracture and its radiologic appearance in the diagnostic work-up of bone tumors. It also addresses the issue of when to contact the orthopaedic surgeon. The key to early detection of risk in bone lesions and their high-quality targeted reporting is familiarity with the possible clinical presentation, biomechanical effects of the anatomical localization, and the lesion types. Imaging has a pivotal role in the management of patients with a spine bone tumor, guiding the choices of the orthopaedic surgeon. Although MRI has robust reliability, some imaging features of benign lesions and malignancies overlap, making the differential diagnosis challenging. Several imaging tools are now available that may improve differential diagnosis.

Luca Maria Sconfienza, Italy, and colleagues from Greece and Italy present “Differential Diagnosis of Spine Tumors: My Favorite Mistake.” This review provides an overview of the main challenges encountered when dealing with a spine bone tumor in daily clinical practice, providing some tricks of the trade to avoid possible diagnostic traps. Ewing's sarcoma is a rare, highly malignant anaplastic stem cell tumor consisting of uniform, densely packed small monomorphic cells with round nuclei. On radiographs, Ewing's sarcoma typically presents as a permeative lesion in the diaphysis of a long bone in a child. A large soft tissue component is another characteristic feature best depicted by MRI. Primary osseous lymphomas are most often highly malignant B-cell lymphomas consisting of diffuse round cell infiltrates that resemble the appearance of Ewing's sarcoma. Although there is no typical imaging appearance of an osseous lymphoma, it should be considered, and histologic confirmation should be sought in an adult presenting with an aggressive lesion in the metaphysis or diaphysis of a large long bone, the pelvis, or the vertebral column.

Marc-André Weber, Germany, and colleagues from Greece, Macedonia, and Belgium take discussion a step further with “Ewing's Sarcoma and Primary Osseous Lymphoma: Spectrum of Imaging Appearances,” presenting a pictorial essay of the various presentations in the imaging of these two entities.

The next article by Olympia Papakonstantinou, Greece, and colleagues from the United Kingdom and Austria reviews T2-weighted hypointense tumors and tumor-like lesions. It includes a discussion of the spectrum of T2 hypointense tumors and tumor mimickers that can arise from the bones, joints, and soft tissues. Although most MSK tumors are hyperintense on T2-weighted MR images, some T2-weighted hypointense tumors and tumor-like lesions are frequently encountered, and knowledge of their wide differential diagnostic range is mandatory in everyday clinical practice.

In “Nerve Tumors: What the MSK Radiologist Should Know,” Alberto Tagliafico, Italy, and colleagues from the United Kingdom and Italy discuss that there is still no single imaging feature or reproducible criteria or a combination of features to differentiate reliably between neurofibroma and schwannoma or to discriminate confidently between benign and malignant neurogenic tumors. But often a combination of MRI and ultrasound can help characterize these neurogenic tumors.

The final article, “Surprising Bone and Soft Tissue Lesions of the Chest: Pictorial Review,” is by Bert Degrieck, Belgium, and colleagues from Italy and Belgium. Although plain radiographs of the chest are usually requested to evaluate the heart, lung, and mediastinum, many bone and soft tissue lesions and metabolic and congenital lesions can be visible, presenting as “surprising” lesions. With 14 case presentations, the authors address this issue and demonstrate that MSK lesions visible on chest radiographs are, in fact, not uncommon.

We expect this issue will provide a helpful update on many of the challenges encountered in the evaluation of bone and soft tissue tumors. We would like to thank each of the authors for contributing their time and expertise to this outstanding issue. We hope you find a useful pearl or two to take away from it that will aid in your daily MSK interpretation.