Bone Tumors

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Pediatric Bone Tumors: Overview - Little Skeletons, Big Issues

  • Pediatric bone tumors: classified as benign or malignant.
  • Incidence: Uncommon, represent ~5-10% of childhood cancers; peak during adolescent growth spurt.
  • Malignant types: Osteosarcoma (most common primary), Ewing Sarcoma.
  • Benign types: Osteochondroma (most common benign), Non-ossifying fibroma, Osteoid osteoma.

⭐ Most pediatric bone tumors are benign, with osteochondroma being the most common overall.

Benign Bone Tumors: Common Types - Friendly Phantoms

TumorKey FeaturesLocationX-ray Appearance
OsteochondromaMost common. Cartilage-capped exostosis. Pain if impinges.MetaphysisBony stalk, points away from joint
Osteoid Osteoma< 2 cm lesion. Severe night pain, relieved by NSAIDs.Long bone cortexRadiolucent nidus, surrounding sclerosis
Non-ossifying fibromaAsymptomatic, incidental. Fibrous cortical defect. May resolve spontaneously.MetaphysisEccentric, lytic, "soap bubble"
Aneurysmal Bone CystExpansile, blood-filled. Pain, swelling. Pathological fractures.MetaphysisLytic, "fallen leaf" sign possible

⭐ Osteoid osteoma's characteristic night pain is dramatically relieved by NSAIDs like aspirin.

Osteosarcoma: Key Features - Metaphyseal Marauder

  • Most common primary malignant bone tumor.
  • Site: Metaphysis (distal femur > prox. tibia > prox. humerus).
  • Age: Bimodal: 10-20 yrs, >65 yrs (Paget's, radiation).
  • X-ray:
    • Sunburst appearance.
    • Codman's triangle.
    • Mixed lytic/sclerotic.
  • Histo: Malignant osteoid.
  • Markers: ↑ ALP, ↑ LDH.
  • Assoc.: RB1, TP53 (Li-Fraumeni), prior radiation, Paget's.
  • 📌 OS: Old Sun (Sunburst), Codman the Old Man (Codman's triangle), Metaphysis (Most common site).

⭐ The 'sunburst' appearance and Codman's triangle on X-ray are classic radiological signs of Osteosarcoma.

Ewing Sarcoma: Key Features - Diaphyseal Danger Zone

  • Small round blue cell tumor; neuroectodermal origin. 2nd common, children.
  • Site: Diaphysis (long bones, pelvis).
  • Genetics: t(11;22)(q24;q12) → EWS-FLI1.

    ⭐ The t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein, is pathognomonic for Ewing Sarcoma.

  • Clinical: Pain, swelling; systemic: fever, wt loss, ↑ESR.
  • X-ray: Lytic, "onion-peel", "moth-eaten". Ewing Sarcoma X-ray with Onion Peel Appearance
  • Histo: Small round blue cells; PAS+; Homer-Wright. Ewing Sarcoma histology: small round blue cells
  • 📌 EWING: Eleven Twenty-two (t(11;22)), Onion skin, Wobbly (systemic symptoms), In the middle (Diaphysis), Neuroectodermal origin.

Bone Tumor Workup: Diagnosis & Staging - Cracking Cases

  • Clinical Clues: Persistent pain (esp. night pain, unrelated to activity), palpable mass, swelling, limp, or pathological fracture.

  • Diagnostic Pathway:

  • Biopsy Gold Standards:

    • Crucial; ideally by treating orthopedic oncologist.
    • Types: Core needle (preferred), incisional.
    • Principles: Longitudinal incision, avoid neurovascular bundles & joint contamination.

    ⭐ A poorly planned biopsy can compromise limb-salvage surgery; always involve an orthopedic oncologist early.

  • Staging Systems:

    • Enneking: Benign (1-latent, 2-active, 3-aggressive); Malignant (IA/B low/high grade intracompartmental, IIA/B low/high grade extracompartmental, III-metastases).
    • AJCC TNM: Adapted for specific tumors (e.g., Ewing Sarcoma, Osteosarcoma). Considers Tumor size (T), Nodal status (N), Metastasis (M).

High‑Yield Points - ⚡ Biggest Takeaways

  • Osteosarcoma: Most common malignant; metaphysis (knee); sunburst appearance, Codman's triangle.
  • Ewing Sarcoma: Diaphysis/flat bones, onion-skin periostitis, t(11;22), small round blue cell tumor.
  • Key symptoms: Night pain, swelling, palpable mass, pathological fractures.
  • Lungs: Most common site for metastasis from both tumors.
  • Osteochondroma: Most common benign bone tumor.
  • Management: Chemotherapy + Surgery; Ewing's is radiosensitive, Osteosarcoma often radioresistant.

Practice Questions: Bone Tumors

Test your understanding with these related questions

Ganga Ram, a 19-year-old male with a short history of pain in the right groin that worsens at night time and has a small circumscribed sclerotic swelling over diaphysis of femur. Likely diagnosis is:

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Flashcards: Bone Tumors

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The most common cause of metastasis in bone in children under 6 years of age - _____.

TAP TO REVEAL ANSWER

The most common cause of metastasis in bone in children under 6 years of age - _____.

adrenal neuroblastoma

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