Review Topic
  • A 12-year-old boy presents to his pediatrician for a bony mass on his left leg. He denies any trauma to the area and it is not associated with pain. Physical examination demonstrates a palpable painless mass close to the knee joint. A radiograph of the knee demonstrates a bony outgrowth with clear, regular margins.
  • Overview
    • a benign chondrogenic bone tumor (osteocartilaginous exostosis)
      • when there are 2 or more exotoses, it is termed hereditary multiple osteochondromas (HME)
  • Epidemiology
    • incidence
      • most common benign bone tumor
    • demographics
      • children and adolescents
      • more common in males
    • location
      • typically affects      
        • long bones in the legs
        • pelvis
        • shoulder blade
  • Pathophysiology
    • occurs in bone that is undergoing endochondral ossiffication and results in an outgrowth of the growth plate
      • the cartilaginous cap serves as the source of growth over the bony spur
  • Genetics
    • mutation
      • EXT1 (on chromosome 8) or EXT2 (on chromosome 11)
  • Prognosis
    • associated with normal life expectancy
    • rare transformation to chondrosarcoma
  • Osteochondroma
    • symptoms
      • usually present with painless mass
      • may have mechanical symptoms or symptoms of neurovascular compression
    • physical exam
      • palpable mass
      • may have mechanical symptoms secondary to mass
  • Hereditary multiple exostosis
    • symptoms
      • often presents with limb deformities (short stature, deformed joints, and decreased range of motion)
      • most common sites of deformity include the knee, forearm, and ankle
    • physical exam
      • extremity deformity
      • decreased joint range of motion
  • Radiograph
    • indication
      • initial imaging study
    • findings
      • sessile (broad base) or pedunculated (narrow stalk) lesions found on the surface of bones 
      • cortex of the lesion is continous with the cortex of the bone
      • cavity of the lesion is continous with the medullary cavity of the bone
  • Osteosarcoma
    • differentiating factors
      • painful enlarging mass or fracture
      • Codman triangle or sunburst pattern on radiography of the bone
  • Lifestyle
    • observation
      • indication
        • asymptomatic cases
  • Surgical
    • excision
      • indication
        • in symptomatic cases
  • Tendon, soft tissue, vascular, and nerve compression
  • Bone deformities
  • Fracture
  • Growth impairment
  • Chondrosarcoma

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