Which of the following is not true about osteosarcoma?

Most commonly arises in the epiphyseal region

Seen in the metaphyseal region of the long bones

Secondary osteosarcoma is seen in older age groups

Which statement is incorrect about the pathology of the bone tumor?

Chemotherapy is the treatment of choice for all bone tumors.

Tumor arises from epiphyseal to metaphyseal region

A 2 year old child is seen on a routine visit in the pediatric clinic. Abdominal examination demonstrates a palpable, non-tender mass on the left side of the abdomen. The mother had no idea the mass was present and the pediatrician did not note the presence of the mass at the child's 18-month's visit for immunisation. Physical examination is otherwise unremarkable. If a CT guided biopsy of the mass were performed, which of the following histological patterns would be most suggestive of the likely diagnosis?

Triphasic pattern with tubule formation, spindle cells, and blastemal elements

Invasive papillary lesions with delicate connective tissue stalk covered with epithelium resembling that lining the bladder.

Cords of clear cells with rounded or polygonal shape and abundant clear cytoplasm

Small dark cells embedded in a finely fibrillar matrix with formation of numerous rosettes

Bone Tumors for FMGE: High-Yield Pediatrics Lessons

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

Tumor	Key Features	Location	X-ray Appearance
Osteochondroma	Most common. Cartilage-capped exostosis. Pain if impinges.	Metaphysis	Bony stalk, points away from joint
Osteoid Osteoma	< 2 cm lesion. Severe night pain, relieved by NSAIDs.	Long bone cortex	Radiolucent nidus, surrounding sclerosis
Non-ossifying fibroma	Asymptomatic, incidental. Fibrous cortical defect. May resolve spontaneously.	Metaphysis	Eccentric, lytic, "soap bubble"
Aneurysmal Bone Cyst	Expansile, blood-filled. Pain, swelling. Pathological fractures.	Metaphysis	Lytic, "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".
Histo: Small round blue cells; PAS+; Homer-Wright.
📌 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.

Continue reading on Oncourse

CONTINUE READING — FREE

or get the app

App Store|Google Play

Bone Tumors