P3

• Bone tumors and tumor-like lesions are rare but disfiguring neoplasms, such that surgery required for their treatment can be challenging
• Bone tumors and tumor-like lesions are not very common but lethal in 50% of the cases
• Bone tumors and tumor-like lesions develop during the first several decades of life, with the greatest frequency occurring within the first 3 decades
• Bone tumors and tumor-like lesions have a propensity for long bones of extremities
• Bone tumors and tumor-like lesions have a predilection for certain age groups and particular anatomic sites
• Bone tumors and tumor-like lesions are classified according to the normal cell or matrix they produce or according to their clinicopathologic features
• Benign lesions/cases outnumber malignant cases of bone tumors
• In older patients, bone tumors are more likely to be malignant
• Metastatic or hematopoietic bone tumors outnumber primary bone tumors
• The most common malignant bone tumors are metastatic lesions
• Most common primary bone tumors

  • Osteosarcoma
  • Chondrosarcoma
  • Ewing's sarcoma
• Malignant bone tumors or bone sarcomas are lethal in 50% of cases, excluding neoplasms originating from hematopoietic cells like myeloma, lymphoma, and leukemia
• Osteoid osteoma


  Benign bone-producing tumor with identical histologic features as osteoblastoma, but differs in size, sites of origins, and symptoms
• Osteoblastoma


  Benign bone-producing tumor with identical histologic features as osteoid osteoma, but differs in size, sites of origins, and symptoms
• Differences between osteoid osteoma and osteoblastoma

  • Size (osteoid osteoma less than 2cm, osteoblastoma more than 2cm)
  • Symptoms (osteoid osteoma has severe nocturnal pain responsive to NSAIDs, osteoblastoma has pain unresponsive to NSAIDs)
  • Treatment (osteoid osteoma treated with radiofrequency ablation, osteoblastoma treated with en bloc curettage)
  • Site of origin (osteoid osteoma in appendicular skeleton, osteoblastoma in posterior spine)
• Osteoid osteoma and osteoblastoma have identical histologic features, presenting as round to oval masses of hemorrhagic gritty tan tissue
• Radiographic features of osteoid osteoma include a thick rind of reactive cortical bone encircling the lesion and a nidus (small round lucency that may be centrally mineralized)
• Radiographic features of osteoblastoma include a sharp zone of transition between the lesion and normal bone
• Osteosarcoma


  The most common primary malignant tumor of bone (20% of bone cancers), producing an osteoid matrix or mineralized bone
• Features of osteosarcoma


  • Bimodal age presentation (majority in younger than 20 years old, also in older adults as sequela of Paget's disease, bone infarcts, prior radiation)
  • Male predominance (1.6:1)
  • Metaphyseal region of long bones or area of highest growth plate activity as location
• Clinical manifestations of osteosarcoma

  Presents as painful, progressively enlarging mass, often around the knee involving distal femur or proximal tibia; can also present with sudden bone fracture
• Radiologic features of osteosarcoma include Codman's triangle (elevation of the periosteum) and sunburst pattern (stretching of Sharpey's fibers perpendicular to the bone), but diagnosis relies on histologic confirmation
• Osteosarcomas present as large bulky masses with gritty grayish white cut surface containing areas of hemorrhage and cystic degeneration, with destruction of the surrounding bony cortex
• Microscopically, osteosarcomas show pleomorphic cells with larger hyperchromatic nuclei, bizarre tumor giant cells, abnormal mitosis, vascular invasion and extensive necrosis, with production of neoplastic bone or osteoid

  
• Osteosarcoma subtypes


  • Intramedullary
  • Intracortical
  • Surface
  • Low grade
  • High grade
  • Primary (underlying bone unremarkable)
  • Secondary (pre-existing disorders)
  • Osteoblastic
  • Chondroblastic
  • Fibroblastic
  • Small cell
  • Giant cell
  • Telangiectatic
• The most common subtype of osteosarcoma is primary, intramedullary, osteoblastic, and high grade
• Osteosarcomas spread hematogenously, with the lungs being the most common site of metastasis
• 1. year survival rates are 60-70% without overt metastasis, but less than 20% with overt metastasis, recurrent disease, or secondary osteosarcoma
• Osteochondroma


  The most common benign tumor of bone, a benign cartilage-capped tumor attached to the underlying skeleton by a bony stalk
• Features of osteochondroma


  • Most distinct feature is the formation of a cartilage cap
  • Majority (85%) present as solitary lesions, may also occur as multiple lesions as part of multiple hereditary exostosis syndrome
  • Solitary lesions present in late adolescence or early adulthood, multiple exostosis present in early childhood
  • Males more affected than females
  • Usually arise in bones of endochondral origin, especially near the growth plate of long tubular bones and in the pelvis, scapula, ribs
• Clinical presentation of osteochondroma

  Presents as a slow growing mass with or without pain that stops growing at the time of closure of the growth plate
• Multiple osteochondromas, though benign, have a risk of progressing to a chondrosarcoma in patients with multiple exostosis syndrome
• Osteochondroma


  Benign cartilage-capped tumor attached to underlying skeleton by a bony stalk
• Osteochondroma


  • Most distinct feature: formation of cartilage cap
  • Majority (85%) present as solitary lesions
  • May occur as multiple lesions as part of multiple hereditary exostosis syndrome
• In both types of osteochondromas, males are more affected than females
• Multiple osteochondromas, though benign, have a risk of progressing to a chondrosarcoma (in patients with multiple exostosis)
• Chondroma


  Benign tumor of hyaline cartilage which may arise within the medullary cavity (ENCHONDROMA) or on the surface of bones (JUXTACORTICAL CHONDROMAS)
• Chondroma is the most common of the intraosseous cartilage tumors
• Chondrosarcoma


  Malignant bone tumors that produce hyaline cartilage
• Chondrosarcoma is the 2nd most common malignant matrix-producing tumor of bone