Abstract
A tumor can be thought of as any mass in the soft tissues or bone that otherwise should not be there. Orthopaedic oncology specializes in the diagnosis and treatment of both benign and malignant tumors of the bones and tissues of the extremities, pelvis, and spine. Upon initial identification, a systemic approach to the evaluation of these lesions aids in providing a timely diagnosis and proper referral. While benign bone lesions, such as unicameral bone cysts, may require no intervention, other benign bone lesions, such as giant cell tumors, may require operative intervention or long-term follow-up. Despite their benign characterization, some lesions can be locally aggressive or even metastasize. Malignant bone and soft-tissue tumors often require multidisciplinary care, including operative intervention. The orthopaedic oncologist also plays a role in managing systemic processes such as metastatic disease, multiple myeloma, and lymphoma.
Keywords
Tumor, oncology, cancer, sarcoma, mass
A tumor can be thought of as any mass in the soft tissues or bone that otherwise should not be there. Upon initial identification, a systemic approach to the evaluation of these lesions aids in providing a timely diagnosis and proper referral.
Evaluation and Staging
History and Physical Examination
The history and physical examination are the first steps in evaluating any bone lesion or soft-tissue mass. Age is integral to the development of a differential diagnosis. Whereas a bone lesion in an older patient is most likely to be a metastatic lesion, younger patients are more likely to present with primary bone tumors ( Table 20.1 ).
| Age (Years) | Tumor |
|---|---|
| <5 | Metastatic (especially metastatic nephroblastoma and nephroblastoma) |
| 5–30 | Ewing sarcoma |
| 5–20 | Osteosarcoma |
| 10–25 | Chondroblastoma |
| 10–20 | Osteochondroma |
| 5–15 | Simple bone cyst |
| 10–20 | Aneurysmal bone cyst |
| 2–16 | Nonossifying fibroma |
| 20–40 | Giant cell tumor |
| >40 | Myeloma |
| >40 | Metastatic carcinoma (breast, prostate, thyroid, kidney, lung) |
| >50 | Chondrosarcoma |
| >50 | Chordoma |
Hallmark Signs and Symptoms
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Insidious onset of pain, especially at night and at rest
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Systemic symptoms including fatigue, night sweats, fevers, and unintentional weight loss
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Enlarging mass or limb asymmetry
Physical Examination
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Note any masses and their features (firm vs. soft, fixed vs. mobile, deep vs. superficial).
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Examine the entire extremity and perform a thorough neurovascular examination. Subtle changes may be present secondary to the mass effect of the lesion. Note any thrill or bruit.
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Examine regional lymph nodes, which are the third most common sites of musculoskeletal tumor metastases after the lungs and bones.
Imaging
Conventional Radiographs
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Initial step in evaluation of all lesions, bone or soft tissue.
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Obtain orthogonal views (anterior-posterior and lateral) of the entire bone and adjacent joints involved.
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Note what the lesion is doing to the bone and how the bone appears to be reacting.
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A large expansile lesion with cortical disruption, no clear margins, and corresponding soft-tissue mass is more likely to be malignant.
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A small, well-circumscribed lesion with intact cortices and no soft-tissue mass is more likely to be benign.
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Note the location of the lesion within the bone (epiphysis vs. metaphysis vs. diaphysis, cortical vs. intramedullary), as different lesions have a propensity to form in certain regions of the bone.
Bone Scan
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Used to detect multifocal and/or distant sites of bone disease.
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Multiple myeloma, lymphoma, and metastatic renal cell or thyroid carcinomas may appear cold on bone scan.
Computed Tomography
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Chest computed tomography (CT) to evaluate for lung metastases (the predominant site of metastatic disease) and regional adenopathy.
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Chest and abdomen/pelvis CT to evaluate for primary site in case of metastatic lesions.
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Primary method of evaluating certain bone lesions, for example, osteoid osteoma.
Magnetic Resonance Imaging With Contrast
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Primary method of evaluating characteristics of both bone and soft-tissue lesions
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Demonstrates anatomic relationship of mass and surrounding structures
Positron Emission Tomography
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Useful for detecting metastatic or recurrent disease (particularly sarcoma) and tumor response to chemotherapy
Tumors of the Bone
The American Cancer Society reports that there were approximately 2400 cases of primary bone cancer in 2007. The incidence of all bone tumors and tumor-like conditions is unknown, as many benign lesions are either not ever identified or not reported. A lesion may go undetected until found incidentally on radiographs performed for a remote complaint or after trauma. Any painful lesion or lesion resulting in a pathologic fracture requires further investigation. In addition, large lesions, lesions in critical weight-bearing areas (e.g., subtrochanteric femur), and lesions with associated periosteal reaction or soft-tissue mass require evaluation. The radiographic appearance of benign, benign aggressive, and malignant lesions may demonstrate significant overlap.
Common Benign Bone Lesions
Osteoid Osteoma
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Benign lesion characterized by significant pain, which may lead to secondary physical examination findings such as scoliosis (painful), limb length inequality, and synovitis/joint effusions, depending on location.
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Typical age range is 10 to 30 years, and the most common locations are the long bones of the lower extremities and the posterior elements of the spine.
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A hallmark feature is night pain, often causing awakening, and marked symptomatic improvement with nonsteroidal antiinflammatory drugs/aspirin.
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Radiographically, a small lucent lesion (<1 cm) surrounded by a reactive area of dense cortical bone that can be further delineated with CT ( Fig. 20.1 ).
Fig 20.1
(A) Radiograph of the right proximal femur demonstrates a well-circumscribed lytic lesion on the posterior cortex of the femur. (B) Axial slice of a computed tomography scan of the proximal femur further delineates the reactive bone around a radiolucent nidus that is less than 1.5 cm.
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Osteoid osteomas will gradually burn out, so the pain can be managed with long-term nonsteroidal antiinflammatory medications. Many patients, however, prefer intervention, and the nidus can be removed surgically or destroyed with radiofrequency ablation.
Osteoblastoma
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Benign bone-forming tumor presenting in the second or third decade with progressive pain that is not worse at night and does not improve with nonsteroidal antiinflammatory drugs (NSAIDs).
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Occur most commonly in long bones and posterior elements of the spine.
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Radiographically, these lesions are >2 cm, geographic and radiolucent, with a thin rim of sclerotic, reactive bone. Variable ossified matrix. Can appear aggressive with periosteal reaction and soft-tissue mass.
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Magnetic resonance imaging (MRI) demonstrates relationship of tumor to surrounding structures.
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Treatment includes extended intralesional curettage with adjuvant treatment (e.g., phenol, liquid nitrogen, argon beam) and grafting of the defect. En bloc excision may be necessary in aggressive or recurrent lesions. Recurrence rates vary from 10% to 20%.
Osteochondroma
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Benign cartilage-forming tumor, also known as an osteocartilaginous exostosis, identified incidentally or due to discomfort from soft-tissue impingement in young adults. Most often solitary but may be multiple when part of the multiple hereditary exostosis syndrome, an autosomal dominant condition.
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Radiographically, the lesions are broad based (sessile) or stalk-like (pedunculated) with corticomedullary continuity ( Fig. 20.2 ).
Fig 20.2
Radiograph of the knee of a skeletally immature patient with a pedunculated osteochondroma off of the medial distal femur. Note the continuity between the medullary cavity of the femur and the osteochondroma.
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The pathologic cap of the lesion is composed of cartilage that is subject to the same growth regulation as the physes, so osteochondromas grow until skeletal maturity.
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Low risk of degeneration to a secondary chondrosarcoma. Any growth after cessation of skeletal maturity or increasing size of the cartilage cap is a cause for concern and may indicate malignant transformation.
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Surgical excision for symptomatic or suspicious lesion.
Enchondroma
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Benign cartilaginous tumor found, often incidentally, within the medullary canal of virtually any bone in the third or fourth decade. The most common location is the hand, where they can present with pathologic fracture ( Fig. 20.3 ).
Fig 20.3
A radiograph of the left hand demonstrates a pathologic fracture through an enchondroma of the proximal phalanx of the small finger. The enchondroma is a well-defined lucent lesion with characteristic “popcorn” stippling internally and cortical thinning radially predisposing to a pathologic fracture.
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Radiographs reveal a circumscribed lesion with good margination. Speckled calcifications, minimal endosteal thinning, and (very) mild bone expansion may be found.
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These lesions can be part of a genetic syndrome, characterized by multiple enchondromas—Ollier disease or Maffuci syndrome.
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Low risk of malignant transformation to low-grade chondrosarcoma. Risk increased significantly in setting of enchondromatosis (Ollier disease, Maffuci syndrome).
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Treatment typically consists of serial radiographs with curettage and bone grafting reserved for clinically aggressive or symptomatic lesions.
Chondroblastoma
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Benign, locally aggressive bone tumor typically found in the epiphysis of long bones, most often around the knee, proximal humerus, or proximal femur
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Present in the second or third decades of life with joint pain and swelling.
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Radiographs reveal a destructive epiphyseal lesion with a thin sclerotic rim, often with stippled or punctate calcification ( Fig. 20.4 ).
