Pediatric Orthopedic Tumors



Pediatric Orthopedic Tumors


Blaze D. Emerson

Bijan J. Ameri





  • The most common malignant bone tumor is osteosarcoma (OS) and the Ewing sarcoma family of tumors (ESFT), which account for 90% to 94% of malignant bone tumors.1,2


  • OSs are the most common primary bone tumor in children with 56% of cases.


  • It is estimated that 3% of all childhood cancers are OSs, whereas ESFTs are responsible for 34% to 36% of childhood bone cancers.2


  • Eight types of benign bone tumors have been described: osteoma, osteoid osteoma, osteoblastoma, giant cell tumor, aneurysmal bone cyst, fibrous dysplasia, and enchondroma.


  • These tumors may be further divided based on the matrix or substance they produce as bone-forming, cartilage-forming, fibrous, and vascular.3


  • Benign tumors may be static and require no further workup; others may be locally aggressive and require constant supervision and/or treatment.


  • In most cases, the age of the child, location of lesion, and radiographic appearance are helpful in determining the underlying pathology.4


EPIDEMIOLOGY AND ETIOLOGY



  • According to the Surveillance Epidemiology, and End Results (SEER) Cancer Statistics Review of the National Cancer Institute program, 3260 new cases of bone and joint cancer will occur in the United States in 2017.


  • This accounts for approximately 0.2% of all cancers.


  • Individuals younger than 20 years will account for 26.4% of these cases.


  • Furthermore, 1550 cancer deaths or 0.3% of all cancer deaths in 2017 will be caused by cancers of the bone or joint.


  • Overall, the 5-year relative survival is 67.7%.5



  • Primary bone tumors are relatively uncommon, although malignancy of the bone or joints is the third leading cause of cancer deaths in individuals younger than 20 years.25


  • It is estimated that 3% to 6% of childhood cancer is attributable to malignant bone tumors.1


  • The incidence of benign bone tumors is higher than malignant lesions; however, benign tumors are difficult to estimate, as most are found incidentally and patients tend to be asymptomatic.6


CLINICAL PRESENTATION



Pain



  • Benign lesions are most often asymptomatic, but patients may present with localized pain, swelling, deformity, or a pathologic fracture.


  • Aggressive benign bone tumors may cause mild/dull pain that is slowly progressive and worse at night.7


  • Malignant lesions more commonly present with localized pain of several month’s duration that is rapidly progressive.


Age



  • Benign bone tumors tend to present during the second decade of life, except for ossifying fibromas, which appear during the first 5 years.


  • OSs peak between 13 and 16 years and seem to be associated with the adolescent growth spurt.8


Physical Examination



  • During examination, it is important to assess bone tenderness, swelling, deformity, joint range of motion, neurologic function, and vascular function.


  • Osteochondromas, OSs, ESFT, and periosteal chondromas may sometimes be palpated. Aggressive tumors may compromise neurovascular function.


  • Overlying erythema or warmth may indicate an underlying infection, which can confuse clinicians.





SURGICAL MANAGEMENT



  • Children with bone tumors should be referred to an orthopedic surgeon who specializes in these lesions.


  • Most benign tumors may be followed with serial examinations and imaging; however, locally aggressive or malignant lesions may need surgical resection with possible adjuvant therapy.



OSTEOSARCOMA



  • Primary OS is the most common bony malignancy of children accounting for 56% of cases of malignant bone lesions.2


  • OS has a worldwide annual incidence rate of 1 to 3 per cases per million and when adjusted for age 4.4 per million cases per year.9


  • OSs are malignant tumors characterized by the overproduction of osteoid (immature bone).



  • The tumor is frequently found in the metaphysis of long bones; in decreasing frequency, the femur (75% of cases), proximal tibia, and proximal humerus are the most common locations.2


  • Most patients have no underlying pathogenesis; however, genetic disposition and exposure to ionizing radiation or chemotherapy are risk factors that have been implicated in the formation of OS.




  • Secondary OS due to prior chemotherapy or radiation therapy has been postulated to cause up to 3% of new cases.10


  • The 2 most common genetic predisposition syndromes related to OS are Li-Fraumeni syndrome and retinoblastoma.


  • OS predominately affects young adults and adolescents, appearing to correlate with the pubertal growth spurt.


  • Cases of older patients with OS are generally related to prior radiation/chemotherapy exposure or Paget disease.


  • A genetic predisposition should be assumed when a child younger than 5 years presents with OS.1






Figure 56.3 Ewing sarcoma: L5. A, AP lumbar spine. B, Tomogram, L5. Observe the lytic destruction of the pedicle of L5 and a portion of the vertebral body (arrows) in this 15-year-old patient. Comment: Ewing sarcoma of the spine is uncommon, occurring in 7% of lesions. When present, the sacrum and lumbar spine are the most common sites. (Reprinted with permission from Yochum TR, Rowe LJ, eds. Yochum And Rowe’s Essentials of Skeletal Radiology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004.)






Figure 56.4 Ewing sarcoma in an 18-year-old woman. Axial soft tissue-windowed CT scan showing the tumoral mass arising from the left aspect of the C3 vertebral body and expanding both in the canal and in the prevertebral soft tissues (arrows). Ewing sarcoma was subsequently diagnosed on open biopsy. The patient was submitted to radiation therapy and polychemotherapy. (Reprinted with permission from Benzel EC, Connolly PJ, DiAngelo DJ, et al, eds. Cervical Spine. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins, a Wolters Kluwer business; 2012.)






Figure 56.5 Osteolysis associated with metastatic Ewing sarcoma. Axial postcontrast T1-weighted MR image of spine shows a large mass (white arrows) centered in left aspect of L3, consistent with metastatic disease. (Reprinted with permission from Iyer R, Chapman T. Pediatric Imaging: The Essentials. Philadelphia, PA: Wolters Kluwer; 2016.)


Clinical Presentation



  • Patients may present after an injury and typically complain of chronic localized pain that waxes and wanes over time.


  • Systemic symptoms are generally absent.


  • Often, a soft tissue mass is appreciated.


  • Laboratory evaluation may demonstrate elevations in alkaline phosphatase, ESR, and LDH.


  • At the time of presentation, 10% to 20% of patients have metastatic disease, primarily the lungs; however, micrometastasis is presumed in all patients (Figure 56.6).11


Imaging

May 5, 2019 | Posted by in PEDIATRICS | Comments Off on Pediatric Orthopedic Tumors
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