Bone Sarcomas

Bone Sarcomas: General Features & Classification - Bone's Bad Bunch

• Primary malignant bone tumors; aggressive with high metastatic potential (lungs common).
• Symptoms: Persistent pain (esp. night pain), swelling, palpable mass, pathological fractures.
• Staging: X-ray (initial), MRI (local extent), CT chest (mets), Biopsy (definitive diagnosis).

Osteosarcoma - Teenage Bone Bane

• Most common primary malignant bone tumor. Bimodal age: 10-20 yrs (peak), >65 yrs (secondary).
• Sites: Metaphysis of long bones (distal femur > proximal tibia > proximal humerus). 📌 "Knee is keen".
• Genetics: Rb, TP53 (Li-Fraumeni). Associated: Paget's disease, prior radiation.
• Clinical: Pain, swelling, palpable mass, pathological fracture, ↓ range of motion.
• X-ray: 📌 "Sun, Cod, Periosteum"
  • Sunburst appearance (tumor spicules).
  • Codman's triangle (periosteal elevation).
  • Periosteal reaction. Lytic/sclerotic/mixed. "Cumulus cloud" (tumor bone).
• Histology: Malignant osteoid production by tumor cells. Pleomorphic spindle cells. High-grade.
• Treatment: Neoadjuvant chemotherapy (MAP: Methotrexate, Adriamycin, Cisplatin), surgical resection, adjuvant chemotherapy.

⭐ Serum Alkaline Phosphatase (ALP) often elevated; prognostic marker.

Ewing's Sarcoma - Small Round Blue Battle

• Epidemiology:

  • Peak age: 10-20 years; 2nd most common primary malignant bone tumor in children.
  • Sites: Diaphysis of long bones (femur, tibia), pelvis, ribs.

• Clinical Presentation:

  • Localized pain, swelling. Systemic: fever, weight loss, ↑ESR (mimics infection).

• X-ray Findings:

  • Permeative lytic ("moth-eaten") lesion in diaphysis.
  • Periosteal reaction: 📌 'Onion-skin' (lamellated), Codman's triangle.

• Histology:

  • Sheets of small, round, blue cells; scant cytoplasm.
  • Homer-Wright rosettes; PAS positive (glycogen).

• Genetics:

  • Translocation: $t(11;22)(q24;q12)$ → EWS-FLI1 fusion protein.

• Treatment:

  • Multimodal: Chemotherapy, surgery, radiotherapy. Highly radiosensitive.

⭐ Ewing's sarcoma is a neuroectodermal tumor, part of the Ewing Sarcoma Family of Tumors (ESFTs), including PNET.

Chondrosarcoma & Other Bone Sarcomas - Cartilage Calamity Crew

• Chondrosarcoma: Malignant cartilage-forming tumor.

  • Age: >40 yrs. Sites: Pelvis, prox. femur, ribs.
  • Clinical: Slow growing; pain, path # (pathological fracture).
  • Treatment: Surgical excision mainstay. 📌 Chondrosarcoma = Cartilage, Chemo/Radio-Resistant.
  • X-ray: Endosteal scalloping, cortical changes, "popcorn"/"rings & arcs" calcification (cartilage matrix).
  • Grading (Prognosis):

    Grade	Features	5-yr Survival
    1 (Low)	Low cellularity, rare mitoses	~90%
    2 (Int)	Mod. cellularity/atypia, mitoses	~70%
    3 (High)	High cellularity/atypia, many mitoses	~40%

  ⭐ Chondrosarcomas are notably resistant to chemotherapy and radiotherapy; complete surgical resection offers the best chance of cure.

• Other Notable Bone Sarcomas:

  • Adamantinoma: Rare, low-grade. Tibia (classic). X-ray: "Soap-bubble", eccentric, osteolytic.
  • Chordoma: Slow, locally aggressive. Notochordal remnants. Sites: Sacrum (common), clivus, spine.

High‑Yield Points - ⚡ Biggest Takeaways

• Osteosarcoma: Most common primary malignancy (excl. myeloma); metaphysis (knee region); Codman's triangle, sunburst pattern; ↑ALP.
• Ewing's Sarcoma: Diaphysis of long bones; small round blue cell tumor; t(11;22) translocation; onion-peel periostitis.
• Chondrosarcoma: Cartilaginous origin; affects adults >40 yrs; common in pelvis, proximal femur/humerus; popcorn calcification.
• Giant Cell Tumor (GCT): Locally aggressive; epiphysis of mature long bones (knee region); soap bubble appearance.
• Most common site of metastasis for bone sarcomas is lungs.
• Adamantinoma: Rare, low-grade malignancy; classically affects tibial diaphysis (mid-shaft).