Imaging of Bone Sarcomas

JN054_Jrnl_50408Cummi.qxd 4/12/07 12:23 AM Page 438 438 Original Article Imaging of Bone Sarcomas Judd E. Cummings, MD; J. Andrew Ellzey, MD; and Robert K. Heck, MD, Memphis, Tennessee Key Words Diagnostic Evaluation Bone sarcoma, imaging, staging Patient evaluation begins with a thorough history and physical examination. Most commonly, patients present Abstract with pain at the affected site. The pain usually does not Identification, staging, and treatment of bone sarcomas rely on both improve and may progress to become independent of clinical and imaging evaluations. Although conventional radiography remains the primary imaging modality for characterizing bone activity. Ultimately, the patient may experience pain at tumors, bone scintigraphy, computed tomography, magnetic rest or at night. resonance imaging, and positron emission tomography can each Although some tumors show a sex predilection (fe- add information for staging and treatment planning. (JNCCN male predominance with giant cell tumor and parosteal 2007;5:438–447) osteosarcoma), this rarely is useful for diagnosis. Similarly, race is of little diagnostic benefit except with Ewing’s sar- Although much less prevalent than other forms of can- coma, which is extremely rare in people of African de- cer, bone sarcomas pose a dilemma in both diagnosis and scent. In contrast, the patient’s age is very helpful in treatment. Fortunately, over the past several decades, the directing the differential diagnosis of a suspected bone advancement and refinement of modalities aimed at treat- tumor.14,15 Examples include primary osteosarcoma, which ing bone sarcomas, such as adjuvant chemotherapy and usually occurs between the ages of 10 and 25 years; Paget’s limb-sparing surgical techniques, have resulted in better osteosarcoma, between 55 and 80 years; Ewing’s sarcoma, 1–13 outcomes for many patients. Appropriate care of pa- between 5 and 25 years; primary chondrosarcoma, be- tients with bone sarcomas is heavily dependent on a tween 30 and 60 years; unicameral and aneurysmal bone prompt and thorough initial evaluation, and a working cysts, younger than 20 years; chondroblastoma, younger knowledge of the various imaging techniques to evaluate than 20 years; giant cell tumor, between 20 and 40 years; bone tumors is paramount for any physician who may en- and metastasis and multiple myeloma, older than 40 counter one of these patients early in the disease course. years.16 Various imaging studies are used in diagnosing, stag- Physical examination should include evaluation of ing, and monitoring bone sarcomas. Conventional radi- the patient’s general health in addition to the affected ography, bone scintigraphy, computed tomography (CT), part. Constitutional symptoms, fever, weight loss, and magnetic resonance imaging (MRI), and positron emis- night pain should be documented. Any mass should be sion tomography (PET) each have strengths and limita- measured and inspected for consistency, mobility, pain, tions. This article describes how these modalities are temperature, fluctuance, and skin changes. A thorough applied to the evaluation and treatment of suspected bone neurovascular examination is recorded and potential sites sarcomas. of lymph node metastasis are palpated. Imaging studies are then used to formulate a working diagnosis and appropri- ately stage the lesion. If these studies, along with the clin- From the University of Tennessee-Campbell Clinic, Department of Orthopaedic Surgery, Memphis, Tennessee. ical information, suggest a malignant bone tumor, the Submitted October 24, 2006; accepted for publication November patient should be referred to a musculoskeletal oncology 13, 2006. The authors have no financial interest, arrangement, or affiliation center without additional tests or biopsy. For several rea- with the manufacturers of any products discussed in the article or their competitors. sons, bone tumors must be completely evaluated before Correspondence: Robert K. Heck, MD, 1211 Union Avenue, Suite proceeding with a biopsy. A thorough evaluation helps 510, Memphis, TN 38104. E-mail: [email protected] narrow the differential diagnosis and leads to a more © Journal of the National Comprehensive Cancer Network | Volume 5 Number 4 | April 2007 JN054_Jrnl_50408Cummi.qxd 4/12/07 12:23 AM Page 439 Original Article 439 Imaging of Bone Sarcomas accurate pathologic diagnosis. The type of biopsy performed and placement of the biopsy incision are de- termined by the extent and potential resectability of the lesion. Additionally, the accuracy of imaging studies such as CT, MRI, or bone scan may be adversely affected by postoperative changes from a premature biopsy.17–22 Biopsy should be performed by a surgeon familiar with musculoskeletal oncology techniques, preferably by one who will perform any definitive pro- cedures. Similarly, if a radiologist is to perform the biopsy, the treating surgeon should be consulted. Conventional Radiography Since the discovery of the x-ray in 1895 by Wilhem Conrad Roentgen, continuous innovations have oc- curred in the application of radiographic imaging to study human disease.23,24 Today, it remains the most widely used imaging modality in medicine and contin- ues to be the gold standard for creating an accurate differential diagnosis of suspected bone lesions.23–27 The appearance of a plain radiograph is a function of Figure 1 Anteroposterior radiograph of the left elbow of a 3-year-old x-ray beam attenuation as it passes through anatomic patient shows a thick, continuous periosteal reaction consistent with structures. The extent of beam attenuation is a func- a benign diagnosis, such as infection, healing fracture, or benign bone tion of the energy of the x-ray beam and the tissue’s tumor. density. Tissues with high attenuation, such as bone, periosteal reaction is frequently associated with appear relatively white, whereas fat or lung tissue al- malignant diagnoses such as osteosarcoma and Ewing’s lows most of the beam to pass through to the film, sarcoma (Figures 2 and 3). producing relatively dark areas.26,27 The appearance of a tumor’s margin is extremely The radiograph produced by the contrasting den- important. In general, most benign bone lesions have sity of human tissues produces a wealth of informa- well-defined margins with a rim of reactive bone sur- tion when analyzed carefully. Plain radiographs should rounding the tumor (Figure 4). Malignant bone le- always be the initial imaging modality for evaluating sions, on the other hand, have poorly defined margins patients with a suspected bone lesion.26,28 Frequently, with a wide zone of transition to normal bone and the patient’s age combined with findings on plain ra- show patchy cortical destruction with early soft-tis- diographs provide enough information to yield an ac- sue extension (Figure 5).32 curate diagnosis.15,26,29 Physicians should consider the Additionally, lesion location must be considered. presence of bone destruction, tumor matrix, periosteal Chondroblastoma (younger patients), giant cell tumor or endosteal reaction, lesion margins, associated soft- (adults), and clear cell chondrosarcoma show a tissue changes, and lesion location.26 The appearance predilection for the epiphyses of bones. In contrast, of the tumor matrix can suggest a particular diagno- Ewing’s sarcoma, histiocytosis, and adamantinoma are sis; infarcts produce a “smoke in the chimney” appear- found more commonly in the diaphyses of long ance, fibrous dysplasia yields a “ground glass” bones.15,22 In the spine, lesions are considered based on appearance in bone,15,30 chondroid lesions often show their location within the vertebral body or the poste- calcified “rings and arcs,”31 and osteosarcoma and os- rior elements. Adults with a lesion of the vertebral teoblastoma frequently show matrix ossification. body usually have metastasis, myeloma, or a Periosteal reactions have been termed solid, spiculated, hemangioma. A vertebral body lesion in a young Codman triangle, or unorganized.15,24 In general, thick patient typically represents histiocytosis, whereas continuous periosteal reaction (Figure 1) is associated lesions in the posterior elements in younger patients with benign entities such as stress fracture, histio- most commonly are osteoid osteoma, osteoblastoma, or cytosis, and infection, whereas thin, discontinuous aneurysmal bone cyst.16 Collectively, this information © Journal of the National Comprehensive Cancer Network | Volume 5 Number 4 | April 2007 JN054_Jrnl_50408Cummi.qxd 4/12/07 12:23 AM Page 440 440 Original Article Cummings et al. Figure 2 Anteroposterior (A) and lateral (B) radiographs of the right distal femur of a 7-year-old patient with osteosarcoma show an ill-de- Figure 3 Anteroposterior radiograph of the right proximal femur of a fined bone-forming lesion with periosteal reaction in the form of a 16-year-old patient with Ewing’s sarcoma shows thin, wispy, “onion Codman triangle. skin” periosteal reaction. should allow an accurate differential diagnosis that can ing unless the lesion is purely lytic, such as multiple help direct further workup and treatment.15,30 myeloma or possible renal cell metastasis, which can 33 Bone Scintigraphy produce false-negative studies. Bone scans detect areas of increased bone metabo- CT lism. A radionuclide, most commonly technetium The development of the CT scanner is credited to (Tc)-99m–labeled diphosphonate, is administered in- Godfrey N. Hounsfield in 1973.38 An advancement travenously and allowed to accumulate in bone. As the

Load more