Bone and Soft Tissue Tumors: Part 2

This second special issue of Seminars in Musculoskeletal Radiology also focuses on bone and soft tissue tumors and has a similar aim: to provide practical guidelines and approaches for daily work and to summarize the state-of-the art imaging and image-guided interventions for bone and soft tissue tumors. Imaging of these tumors has continued to evolve, and the advancement in techniques such as whole-body and hybrid imaging, as well as numerous new image-guided therapies, have maintained our subspecialty's prominence in patient care. Musculoskeletal (MSK) tumor imaging interpretation is often complex and challenging, and the recognition of tumor-like lesions as well as the differentiation of treatment-related changes from tumor recurrences is critical in the daily work of a dedicated MSK radiologist. An organized, systematic approach is essential in differential diagnosis, therapeutic management, and early diagnosis of treatment failure or relapse. Review of the patient's clinical and surgical history and pretreatment imaging studies aid in diagnosis of the latter.

This issue includes eight richly illustrated review articles written by members of the Tumor Subcommittee of the European Society of Musculoskeletal Radiology (ESSR) to provide practicing radiologists, residents, and fellows with the most accurate and current update in MSK imaging. The topics of the selected manuscripts were discussed in several ESSR Tumor Subcommittee meetings.

The first article focuses on the spectrum of entities mimicking tumors of the bone that include various non-neoplastic diseases and anatomical variants based on imaging findings. Proper recognition of “do not touch” lesions is important because misinterpretation of the imaging findings can lead to inappropriate clinical management of the patient. Radiologists have a key role in the management of these patients because most bony tumor-like lesions represent structural changes and not real neoplasms and thus do not require treatment.

The next article nicely reviews the challenges of detecting recurrences and differentiating them from post-therapeutic changes. The authors provide a systematic approach in the follow-up imaging of soft tissue sarcoma patients that will facilitate differentiating post-therapeutic changes from recurrences. As a rule of thumb in the detection of soft tissue tumor recurrences, the following can apply: If a T2-weighted fat-saturated sequence, a short tau inversion recovery sequence, or the water image of a Dixon sequence is considered, recurrence can be excluded in 99% of the cases if (1) no hyperintensity is visible, (2) there is only an “edema-like” diffuse hyperintensity without a circumscribed lesion, and (3) the “feathering” pattern of muscles is visible without any other architectural disturbance, and the picture remains completely unchanged for preliminary examination.

The third article discusses non-neoplastic soft tissue tumors and tumor-like lesions. This review offers an overview of soft tissue sarcoma mimics with guidance on appropriate differential diagnoses. Clinicians are commonly faced with patients presenting with a solitary palpable soft tissue mass, and although most of these are benign, many pathologies can mimic a malignant tumor. The radiologist can really help the clinician here. By combining the relevant clinical history, clinical examination, and specific imaging characteristics, the diagnosis can often be narrowed. A biopsy should be considered of clinically or radiologically indeterminate lesions to exclude an underlying malignancy.

This is a good transition to the next article that compares percutaneous imaging-guided versus open musculoskeletal biopsy. Although the open biopsy is still considered the gold standard for the biopsy of MSK lesions, core needle biopsy can replace it in most cases, with similar accuracy and a low complication rate. The authors recommend biopsies be performed in a tertiary sarcoma center where a multidisciplinary team including at least a tumor surgeon, an MSK pathologist, and an MSK radiologist assesses all procedural steps.

The next article reviews therapy-related imaging findings in patients with sarcoma. It will help radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients to recognize imaging findings related to therapy and not to activity of the previously treated sarcoma. Some of the key messages are that imaging findings are time dependent and often specific in relation to therapy administered and that marrow reconversion may have many facets that make it difficult to differentiate it from diffuse or nodular tumor deposits on magnetic resonance imaging (MRI) and positron emission tomography/computed tomography. Moreover, non-neoplastic increased 18F-fluorodeoxyglucose uptake can be due to inflammatory conditions, bone marrow activation, foreign body reaction, fat necrosis and tissue damage, or muscle activity.

The following two related articles summarize the current repertoire of ablation and stabilization techniques and combined ablation-stabilization techniques as well as the advantages and limitations of each. The authors also demonstrate why such procedures offer value-based alternatives to conventional treatments of specific tumors, although only mostly nonrandomized publications have described the safety, efficacy, and reproducibility of implementing percutaneous therapies both with curative and palliative intent. The authors stress the role of collaborative work within a multidisciplinary team, ideally in a dedicated tumor treatment center, to deliver patient-specific therapy plans that are value based and favored by patients when given the choice.

The final article focuses on the role of whole-body MRI for the detection and characterization of cancer. The authors point out that whole-body MRI enables reliable, sensitive, and specific detection and quantification of cancer burden, with particular application for skeletal involvement and that it is already being integrated into national and international patient care pathways through clinical guidelines for metastasis detection in patients at high risk of melanoma, myeloma, and other primary tumors.

This second special issue on bone and soft tissue tumors offers a helpful update on the many 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 useful pearls to take away from this edition that will aid in your daily MSK interpretations.

Publikationsverlauf

Artikel online veröffentlicht:
11. Dezember 2020