Radiologic Approach to Bone and Soft Tissue Sarcomas a,b,c, b,c,d,e Jamie T. Caracciolo, MD, MBA *, G. Douglas Letson, MD KEYWORDS Imaging Radiology Diagnostic evaluation Bone lesion Soft tissue mass Sarcoma KEY POINTS Diagnostic imaging plays an important role in the evaluation and treatment planning of pa- tients with musculoskeletal tumors. Following a thorough history and physical examination, imaging examinations may be re- quested to evaluate a palpable abnormality; soft tissue mass; or clinical symptoms, such as pain and swelling. In some cases, the clinical presentation including patient age, symptomatology, and past medical history may suggest a specific diagnosis, although in most cases the clinical ex- amination is nonspecific. Whether detected incidentally or in the setting of clinical symptoms, musculoskeletal neo- plasms can often be accurately characterized utilizing appropriate imaging examinations. Diagnostic imaging is a critical component of a multidisciplinary approach to the diag- nosis and treatment of musculoskeletal neoplasms. Following a thorough history and physical examination, imaging examinations may be requested to evaluate a palpable abnormality; soft tissue mass; or clinical symptoms, such as pain and swelling. In some cases, the clinical presentation including patient age, symptomatology, and past medical history may suggest a specific diagnosis, although in most cases the clinical examination is nonspecific. With greater accessibility to and use of advanced imaging modalities, musculoskeletal tumors may be identified incidentally on studies a Musculoskeletal Imaging, Department of Diagnostic Imaging, Moffitt Cancer Center, 12902 Magnolia Drive, WCB-RAD MD/OPI, Tampa, FL 33612, USA; b Department of Radiology, Univer- sity of South Florida Morsani College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA; c Department of Orthopedics/Sports Medicine, University of South Florida Morsani College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA; d Moffitt Cancer Center, Tampa, FL, USA; e Department of Surgery, University of South Florida Morsani College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA * Corresponding author. Musculoskeletal Imaging, Department of Diagnostic Imaging, Moffitt Cancer Center, 12902 Magnolia Drive, WCB-RAD MD/OPI, Tampa, FL 33612. E-mail address: [email protected] Surg Clin N Am 96 (2016) 963–976 http://dx.doi.org/10.1016/j.suc.2016.05.007 surgical.theclinics.com 0039-6109/16/$ – see front matter Ó 2016 Elsevier Inc. All rights reserved. 964 Caracciolo & Letson performed for other reasons. In any of these scenarios, the initial objective of diag- nostic imaging is confirmation of the presence of a musculoskeletal neoplasm versus an alternative explanation of symptoms, such as traumatic injury or infection. When a mass is present, initial characterization of the tumor as benign or malignant is based on features, such as size, margins, enhancement pattern, and internal homogeneity versus heterogeneity. After the initial assessment of benignity versus malignancy, further evaluation may provide for a more specific diagnosis based on tumor charac- teristics, such as anatomic location, morphology, pattern of growth, and intrinsic tumor composition. Ideally, a subspecialized multidisciplinary review of the clinical history, diagnostic imaging, and histopathologic findings at a tertiary cancer referral center would direct optimal patient treatment planning.1–4 This article discusses several important concepts in musculoskeletal tumor imaging and presents relevant imaging features of several common musculoskeletal neo- plasms. A complete and thorough review of musculoskeletal tumor imaging is beyond the scope of this review, with numerous textbooks dedicated to the subject. In this article, we discuss the following: Imaging modalities most often used in the evaluation of musculoskeletal tumors including the advantages and disadvantages of each modality Our approach to the diagnostic evaluation of a newly suspected musculoskeletal neoplasm including determination of risk of malignancy An assessment of internal tumor composition allowing for a specific preoperative histopathologic diagnosis including features of several common soft tissue sarcomas Findings relevant to tumor staging and preoperative planning including response to neoadjuvant therapy Postoperative surveillance plans for local tumor recurrence following limb- salvage procedures IMAGING MODALITIES Several different diagnostic imaging examinations may be used in the initial evaluation of a suspected musculoskeletal neoplasm.5–10 Each modality presents unique advan- tages and disadvantages as shown in Table 1. However, in most cases complemen- tary information is provided by each study. For example, MRI provides greater soft tissue contrast than computed tomography (CT) and therefore often allows for better definition of internal tumor soft tissue composition/intrinsic elements of the tumor, whereas CT better demonstrates tumor mineralization than MRI. In another example, CT better depicts cortical bone involvement including pathologic fractures, whereas MRI better demonstrates medullary edema and bone marrow lesions including skip metastases not uncommonly seen in patients with primary bone tumors, such as osteosarcoma. EVALUATION OF A NEWLY SUSPECTED MUSCULOSKELETAL TUMOR Although a thorough clinical history and physical examination are important in the initial evaluation of a patient with a possible musculoskeletal neoplasm, symptom- atology and physical findings are often nonspecific with significant overlap among pre- sentations of neoplastic and nonneoplastic causes of musculoskeletal complaints.11 Even when findings suggest the presence of a tumor, physical examination is often limited in differentiating benign and malignant neoplasms. As such, most patients with musculoskeletal symptoms are referred for diagnostic imaging. When imaging Table 1 A comparison of imaging modalities commonly used in musculoskeletal tumors Modality Advantages Disadvantages Indications/Usefulness Diagnostic radiography, Diagnostic Ionizing radiation Evaluation of bone tumor margin, orthogonal Accessible Limited evaluation of nonadipocytic matrix, and periosteal reaction roentgenogram Inexpensive soft tissue tumors Soft tissue tumor density and Critical in evaluating bone tumors internal mineralization Demonstrates tumor mineralization and adipocytic tumors CT Accessible Ionizing radiation Evaluate tumor matrix Rapid acquisition/short scan time Less soft tissue contrast resolution Involvement of cortical bone Contiguous imaging of large anatomic compared with MRI including pathologic fractures regions Tumor staging including chest CT Greater spatial and temporal for pulmonary metastases resolution than MRI CT-guided biopsy MRI Greater soft tissue contrast Small confined space; claustrophobia Evaluation of internal tumor resolution than CT Cost composition No ionizing radiation Contraindications to MRI Local extent of disease including Direct multiplanar imaging neurovascular involvement Bone marrow involvement, skip Radiologic Approach to Sarcomas metastases Ultrasound Real-time imaging Limited ability to differentiate soft Ultrasound-guided biopsy Assess solid versus cystic mass and tissue masses tumor vascularity (Doppler) PET Tumor/tissue viability, assessment of Ionizing radiation May help differentiate benign and metabolic activity Reimbursement in sarcomas malignant tumors (ie, neurogenic tumors) Evaluate tumor response to neoadjuvant therapy Whole-body bone scan Assessment of the entire skeletal Ionizing radiation Assessment of skeletal metastases system in a single examination and osteomyelitis Abbreviation: CT, computed tomography. 965 966 Caracciolo & Letson is indicated, initial evaluation begins with orthogonal radiographs of the affected area, which may be followed by cross-sectional imaging, such as CT or MRI as shown in Fig. 1. Step 1: Determination of Risk of Malignancy The first and foremost role of imaging in the setting of a musculoskeletal neoplasm should be confirmation of the presence of a tumor and an assessment of tumor char- acteristics, which help predict benignity versus malignancy. After establishing the risk of malignancy, a further assessment of imaging findings providing for a more specific diagnosis is performed. With patient counseling based on the potential risk of malig- nancy, patients may be appropriately informed on treatment options, which may include surveillance, biopsy, or surgery. For example, consider a young patient with a geographic well-defined metadiaphyseal lytic lesion with circumferential marginal sclerosis. These findings suggest a low likelihood of malignancy and conservative observation may be preferred to biopsy. In cases of soft tissue tumors, the surgical Clinical evaluaon including history and physical raising concern for MSK neoplasm Bone lesion? So ssue mass? Orthogonal radiographs Orthogonal radiographs (note below) Consider paent age, history, locaon; evaluate Contrast-enhanced MRIb to: size, density, matrix, margin, periosteal reacon - Predict benignity vs. malignancy - Evaluate intrinsic tumor composion - Assess local extent of disease, resectability Benign Malignant, indeterminate - Establish baseline prior to neoadjuvant therapy Benign Malignant, indeterminate a Surveillance vs. CT or MRI for further Surveillance vs. Biopsy in consultaon with treatment of benign characterizaon,