Key points in the evaluation of focal bone lesions: from plain film to multidetector CT

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1 Key points in the evaluation of focal bone lesions: from plain film to multidetector CT Poster No.: C-2060 Congress: ECR 2011 Type: Educational Exhibit Authors: I. Rubio Marco, M. Arraiza Sarasa, H. Gómez Herrero, A. De Blas Mendive, I. García de Eulate, C. De Arriba Villamor, A. Ovelar Ferrero, M. Tirapu Tapiz; Pamplona/ES Keywords: Diagnostic procedure, Conventional radiography, CT, Musculoskeletal bone DOI: /ecr2011/C-2060 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 35

2 Learning objectives To review the features that should be evaluated to radiographically differenciate aggressive from non-aggressive focal bone lesions and try to characterize them with plain film and multidetector CT. To identify the main advantages and limits of each technique. To ilustrate this review with some cases studied in our institution. Page 2 of 35

3 Background Radiologists play a key role in the detection and characterization of focal bone lesions. Bone tumors are relatively uncommon in general radiological practice and they show varied appearances, so it is crucial to evaluate the images in a systematic manner to lead to a short differential diagnosis list, guiding the further management of these patients. Conventional radiography is the first-line imaging technique in the evaluation of patients with bone tumors. In the 1960s, Dr. Gwilym Lodwick, professor of radiology, introduced a systematic approach to the radiological diagnosis of bone tumors that is still used today with some more recent contributions, as we will see later. A lot has been said and written about the analysis of focal bone lesions with conventional radiography but not too much with computed tomography (CT). In this exhibit we will review the fundamental radiographic principles in bone tumor diagnosis and the correlation between plain film and CT images, emphasizing on the aditional information provided by the last one. Page 3 of 35

4 Imaging findings OR Procedure details The diagnostic approach to focal bone lesion should include: Clinical information Number of lesions (solitary or multiple) Location Morphologic features 1. Clinical information: The age of the patient is the most important piece of clinical information because the majority of bone lesions show predilection for a specific age range: <20, and >40 years old. Page 4 of 35

5 Fig.: Group age predilection of bone lesions References: Miller T. Radiology 2008; 246: Most primary bone tumors develop in childhood, late adolescence or early adulthood, coinciding with the growth spurt and the time of maximal metabolic activity of bone. Some other parameters that should be evaluated are family history (eg, hereditary multiple osteochondromatosis, neurofibromatosis), past history (eg, evaluation of metastatic disease) and history of presenting complaint (eg, swelling, characteristics of pain...). Laboratory data (eg, alkaline and acid phosphatases, PSA levels, neutrophilia...) may also provide useful information. Page 5 of 35

6 2. Number of lesions: Benign and malignant lesions can be multiple. Benign multiple tumors include polyostotic fibrous dysplasia, enchondromatosis, multiple osteochondral exostoses, Langerhans cells granulomatosis and some more. When malignant multiple bone lesions, they are commonly caused by metastases, multiple myeloma or lymphoma. 3. Location: Certain tumors have predilection for specific bones or specific locations within bones. Fig.: Preferential localization of bone tumors in the skeleton Page 6 of 35

7 References: Differential Diagnosis of Tumors and Tumor-like lesions of Bones and Joints. Adam Greenspan, Wolfgang Remagen Fig.: Specific sites of selected tumors References: Bone Tumors and Tumorlike Conditions: Analysis with Conventional Radiography. Miller T. Radiology 2008; 246: Differential Diagnosis of Tumors and Tumors-like lesions of Bones and Joints. Adam Greenspan, Wolfgang Remagen Within long bones, the radiologist must determine the location in the longitudinal (epiphysis*, metaphysis and diaphysis) and axial (intramedullary, intracortical and surface or juxtacortical -the last ones include parosteal and periosteal lesions-) planes. However, in short or thin tubular bones, such us the metacarpals or phalanges, the entire diametre of the bone can be involved, sometimes making it difficult to determine in which part of the bone the lesion started. Page 7 of 35

8 *An apophysis is equivalent to an epiphysis because both of them are growth centers (the first one does not contribute to the length of a bone and the second one does). Most primary bone lesions are metaphyseal and intramedulary, probably because the metaphysis is the most metabolically active and most vascular area in a growing long bone. Fig.: Common location of tumors and tumorlike bone lesions. Based on the diagram published by Miller, AJR 2009 Vol 246 Num 3 4. Morphologic features: Page 8 of 35

9 a. Patterns of bone destruction: They reflect the growth rate rather than the malignant potential of the lesion. The patterns may range from a discrete well-defined abnormality to an ill-defined infiltrative process. Fig.: Patterns of bone destruction. geographic destruction (type I): bony destruction is confined to one area within which all bone is destroyed. These are slow-growing lesions. Based on their aggressiveness they are subclassified in three groups: - type Ia (sharp margins with thick sclerotic rim), usually benign. Page 9 of 35

10 Fig.: Type 1a geographic bone lesion. Page 10 of 35

11 Fig.: Type 1a geographic lesion. - type Ib (sharp margins without sclerotic rim), usually benign. Page 11 of 35

12 Fig.: Type 1b geographic lesion. Page 12 of 35

13 Fig.: Type 1b geographic bone lesion. - type Ic (ill-defined margins), usually malignant moth-eaten destruction (type II): multiple clustered foci of bone destruction, each one 2-5 mm size. This pattern reflects a lesion that grows rapidly through the medula of the bone but leaves small islands of tissue intact. permeative (type III): multiple ill-defined destructive foci, usually smaller than 1 mm in diameter. This pattern reflects fast-growing lesions. Page 13 of 35

14 Fig.: Type 3 permeated lytic lesion. combination and changing pattern: characterised by a combination of typei, type II and type III in a single lytic lesion and suggests more aggressive local growth. This pattern is usually seen in some benign lesions when they become active, undergo malignant change or fracture. However, while a non-aggressive appearance suggests a benign lesion and an aggressive appearance suggests a malignant one, it is not always the case b. Periosteal reaction: Page 14 of 35

15 Periosteal reaction results when cortical bone reacts to one of many possible insults (trauma, congenital disease, arthritis, metabolic disorders, infection, tumors...). It is another indicator of the biological activity of the lesion as its appearance is determined by the intensity, aggressiveness and duration of the underlying insult. Thus, intense, rapid-acting processes usually result in aggressive periosteal reaction, whereas slower, indolent result in a non-aggressive appearance, regardless of being benign or malignant. One has to bear in mind that the periosteum in children is more active and less adherent to the cortex than in adults, so periosteal reaction can occur earlier and appear more aggressive. The terminology used to describe periosteal reactions is confusing because many terms have been used. In 1965 Lodwick described two "proliferative responses": encapsulated and mottled. In 1966 Edeiken coined the term "periosteal reaction" and described continuous and interrupted forms. To summarize, we can consider two major groups: aggressive and non-aggressive. Page 15 of 35

16 Fig.: Types of non-aggressive and aggressive periosteal reaction. (Based on AJR:193, October 2009) The major goal in evaluating periosteal reaction is to recognize its presence rather than the specific subtype because there is significant overlap in the disease entities that result in aggressive and non-aggressive forms. Sometimes the subtype of periosteal reaction can suggest a certain process: - Solid periosteal reaction (thin or thick): It is radiographically seen as a focal area of cortical thickening. It is a non-aggressive form associated to benign slow processes (healed fracture, osteoid osteoma and osteomyelitis) Page 16 of 35

17 Fig.: Solid periosteal reaction (osteoid osteoma) Page 17 of 35

18 Fig.: Solid periosteal reaction (osteomyelitis). - Single lamella: It is radiographically seen as a dense line 1-2 mm from the outer surface of the bone. If this space fills with new bone, it will result in a solid periosteal reaction. Suggests slow-growing lesion. - Laminated periosteal reaction (onionskin) consists in multiple layers of new bone. It is seen in a variety of lesions (osteomyelitis, sarcomas, chondroblastomas ) - Spiculated periosteal reaction: It is an aggressive form that appears when linear spicules of new bone form along newly form vascular chanels and fibrous bands. It includes: Page 18 of 35

19 - perpendicular/hair-on-end subtype, in which spicules of bone form perpendicular to the periosteal surface. It is highly suggestive of Ewing s sarcoma. It may coexist with a lamellated pattern - sunburst pattern, with spicules radiating in a divergent pattern. It is often associated with conventional osteosarcomas. Fig.: Aggressive periosteal reaction (prostate cancer metastases). Page 19 of 35

20 Fig.: Aggressive periosteal reaction (lung cancer metastases) - Codman triangle: It is an aggressive form that develops when a portion of periosteum is lifted off the cortex by a mass at the leading point. It is commonly seen in osteosarcomas and occasionally with infection, metastases or hemangiomas. Page 20 of 35

21 Fig.: Codman triangle in osteosarcoma. Considering the unilaterality or bilaterality of the periosteal reaction may be helpful in guiding the diagnosis: - If unilateral it is more likely to be caused by a localized process (trauma, infection or tumor). - If bilateral, one has to consider systemic processes (arthritis, metabolic, congenital, genetic, drug-related and vascular entities). In this setting, the age of presentation of the periosteal reaction can often narrow the diagnosis: Page 21 of 35

22 - < 6 months: physiologic periostitis of the newborn, Caffey disease (also known as infantile cortical hyperostosis) and periostitis related to prostaglandine use. - > 6 months: hypertrophic osteoarthropathy, juvenile idiopathic arthritis, hypervitaminosis A and venous stasis. (In the appropiate clinical setting, it is essential to consider nonaccidental trauma as the underlying cause of multiple healing fractures). c. Mineralization of tumor matrix: Recognition of several types of matrix mineralization is helpful in distinguishing different histologic types of primary bone tumors. The term matrix refers to the type of tissue of the tumor (osteoid, chondral, fibrous or adipose), all of which are radiolucent, and mineralization refers to calcification of the matrix. The pattern of mineralization can be a clue to the type of underlying matrix. Page 22 of 35

23 Fig.: Types of tumor matrix. - Osteoid matrix shows an opaque radiographic appearance: mature ossification typically shows greatest density peripherally, but inmature ossification may be difficult to distinguish from calcification because its appearance is like an ill-defined, homogeneus, cloud-like increased density. A bone-forming tumor is frequently indistinguishable from the bone apposition secondary to bone destruction in the setting of a fracture or reactive sclerosis, but the identification of irregular osteoid incompletely mineralized matrix within or adjacent to a bone destruction region is highly suggestive of osteosarcoma. In the same way, cloudlike densities within medular cavity represent tumoral bone. Page 23 of 35

24 - Chondroid matrix shows punctate, flocculent, arclike or ringlike calcifications. Malignant transformation within a chondral lesion may produce focal destruction of the chondral calcifications. Fig.: Chondral mineralization. It can be difficult to distinguish between osteoid and chondroid matrix: the first one usually shows an amorphous appearance and the second one presents in a organized fashion (trabeculated). - Fibrous matrix shows ground-glass density. Punctate calcification may also be present. Page 24 of 35

25 Fig.: Fibrous matrix tumor Faint mineralization in a lession is best assesed using CT, which is mores sensitive than radiographs for differences in attenuation. d. Size The likelihood of malignancy increases with the size of bony lesions. For example, a 1-2 cm chondral lesion in a long bone is most likely to be an enchondroma, while the risk of being a low-grade chondrosarcoma increases if it is greater than 4 or 5 cm. Page 25 of 35

26 The size of a lesion can also be a clue to its diagnosis. For example, the nidus of the osteoid osteoma is less than 1,5 cm in diameter, while the osteoblastoma is larger than 1,5 cm. e. Cortical response: The cortex may be affected by processes that originate in the medullary canal, periosteum, surrounding soft tissue or within the cortex. As a medullary lesion expands, it may cause erosion of the inner surface of the cortex, called endosteal scalloping. It commonly suggests a chondral or fibrous tumor. Fig.: Cortical response (I). Page 26 of 35

27 Fig.: Cortical response (IV). If the medullary lesion is so aggressive that it erodes the inner aspect of the cortex without giving the periosteum time to lay down new bone, the cortex will eventually be destroyed. The most aggressive malignant lesions can penetrate the cortex before cortical destruction is radiographically visible, so apparent preservation of the cortex does not preclude its involvement. Page 27 of 35

28 Fig.: Cortical response (III). On the other hand, cortical expansion implies that endosteal bone removal due to the lesion is occurring at a similar speed to periosteal bone production. Depending on the aggressiveness of the lesion, the ballooned cortex may have normal thickness or be thin. Page 28 of 35

29 Fig.: Cortical response (II). A process that arises either in the periosteum or adjacent soft tissue may erode the outer surface of the cortex. This feature called saucerization or scalloping of the bone s outer surface can reveal the presence of a soft tissue extraosseus mass otherwise not visible. f. Soft tissue component: The presence of soft tissue mass with a bone lesion suggests a malignant process. Exceptions are giant cell tumor, aneurysmal bone cyst, desmoplastic fibroma and eosinophilic granuloma. Page 29 of 35

30 Inflamatory processes may also show soft tissue mass or swelling, but in these cases the mass is not well-defined and fat planes are affected. Fig.: Soft tissue mass (giant cell tumor). Page 30 of 35

31 Fig.: Soft tissue mass (bone metastases secondary to breast cancer). However, the first question should be: is it a bone tumor with extension to soft tissue planes or is it a soft tissue mass that invades the adjacent bone? Some features may help to answer this question: - the size of the bone lesion: if it is a small bone lesion with large soft tissue component associate, it is more likely to be a primary soft tissue tumor. Ewing s sarcoma may be an exception, because it may show a large peritumoral mass. - the presence of periosteal reaction: it is usually associated to bone tumors. - the location of the epicenter of the lesion within the bone. Page 31 of 35

32 To finish, we well summarize the advantages of CT on the field of focal bone lesions: CT remains superior to plain radiography in demonstrating tumor matrix mineralization. - In osteoid osteoma, CT is more sensitive than MR imaging in detecting the nidus, periosteal reaction and cortical thickening. - In osteomyelitis, sequestra and air within regions affected are more readly identificable by CT. - CT is also highly sensitive in the detection of fluid-fluid levels, which are seen most commonly in aneurysmal bone cyst and also in various rarer lesions, including telangiectatic osteosarcoma. - CT aids in the detection of calcium and fat in a soft tissue mass, which are characteristic in certain tumors, such us synovial chondromatosis, myositis ossificans and welldifferenciated liposarcoma. CT serves as guidance for biopsy and, in some cases, for treatment. For example, radio frequency (RF) and treatment of osteoid osteoma. Page 32 of 35

33 Conclusion The radiologist is essential in the diagnosis of a focal lesion in bone. Plain film is still the starting point in the evaluation of these lesions but new techniques add useful information for the management of these patients. By paying attention to the age of the patient and the location and radiological features of the lesion, the radiologist will lead to a short differential diagnosis list, if not to the correct one. A team work among radiologists, surgeons and pathologists is mandatory for correct diagnosis and proper management and follow-up of the patient. Page 33 of 35

34 Personal Information Page 34 of 35

35 References The Evolution of Musculoskeletal Tumor Imaging. Sinchun Hwang, David M. Panicek. Radiol Clin N Am 47 (2009) Periosteal Reaction. Rana, Wu and Eisenberg. AJR 2009; 193: Evaluation of focal bone lesions: basic principles and clinical scenarios. P O Donnell. Imaging 15 (2003), Bone Tumors and Tumorlike Conditions: Analysis with Conventional Radiography. Miller, T. Radiology 2008; Vol 245: Number 3. Malignant and Benign Bone Tumors. Miller, S and Hoffer, F. Radiol Clin North Am 2001; Vol 39: Num 4. Differential Diagnosis of Tumors and Tumors-like lesions of Bones and Joints. Adam Greenspan, Wolfgang Remagen. CT-guided needle biopsies of bone and soft tissue tumors a pathologist's perspective. Mc Carthy, E. Skeletal Radiol 2007; 36: Page 35 of 35