Bone Tumors Practice Questions

Q: What is the most common bone cancer among young men?

Osteosarcoma. **Explanation:** **Osteosarcoma** is the most common primary malignant bone tumor in children and young adults (typically occurring in the 10–25 year age group). It is a mesenchymal tumor characterized by the direct production of osteoid (immature bone) by malignant cells. It most frequently affects the metaphyseal regions of long bones, particularly around the knee (distal femur and proximal tibia). **Analysis of Options:** * **Chondrosarcoma (A):** This is a malignant tumor of cartilage. It is the most common primary bone cancer in **adults over 50 years** and is rare in young men. * **Ewing Sarcoma (B):** While this is the second most common primary bone malignancy in children and adolescents, it is less frequent than osteosarcoma. It typically arises from the **diaphysis** of long bones and presents with a characteristic "onion-skin" periosteal reaction. * **Giant Cell Tumor (D):** This is generally a **benign** (though locally aggressive) tumor. It occurs in a slightly older age group (20–40 years) and is classically located in the **epiphysis** ("ends of bones"). **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Hallmark:** Look for the **"Sunray" or "Sunburst" appearance** and **Codman’s triangle** (periosteal elevation) on X-ray. * **Associated Conditions:** Increased risk in patients with Retinoblastoma (RB1 mutation) and Li-Fraumeni syndrome (TP53 mutation). * **Metastasis:** The most common site of distant spread is the **lungs** (via hematogenous route). * **Serum Marker:** Elevated **Alkaline Phosphatase (ALP)** levels often correlate with disease activity and prognosis.

Q: A 10-year-old boy presents with a fracture of the humerus. X-ray reveals a symmetric radiolytic lesion at the upper end of the right humerus, with a similar lesion present on the left humerus. What is the likely pathology?

Unicameral bone cyst. ### **Explanation** The correct answer is **Unicameral Bone Cyst (UBC)**, also known as a Simple Bone Cyst. **Why it is correct:** A Unicameral Bone Cyst is a benign, fluid-filled cavity typically found in the **metaphysis of long bones** (most commonly the proximal humerus and proximal femur) in children. * **Symmetry:** While UBCs are usually solitary, they can occasionally present symmetrically or multifocally in rare variants or systemic conditions. * **Radiology:** They appear as centrally located, symmetric, well-demarcated radiolucent (lytic) lesions. * **Pathological Fracture:** These are often asymptomatic until a "pathological fracture" occurs. A classic radiological sign post-fracture is the **"Fallen Leaf Sign,"** where a cortical fragment settles at the bottom of the fluid-filled cyst. **Why the other options are incorrect:** * **Osteosarcoma:** This is a highly malignant tumor characterized by an aggressive "moth-eaten" bone destruction, periosteal reactions (**Sunburst appearance/Codman’s triangle**), and soft tissue involvement. It is rarely symmetric. * **Osteoclastoma (Giant Cell Tumor):** This occurs in a slightly older age group (20–40 years) and is typically **epiphyseal** in location. On X-ray, it shows an eccentric, "Soap-bubble" appearance. * **Aneurysmal Bone Cyst (ABC):** Unlike the symmetric/central UBC, an ABC is typically **eccentric**, expansile, and contains blood-filled spaces. It often shows "fluid-fluid levels" on MRI. **NEET-PG High-Yield Pearls:** * **Most common site for UBC:** Proximal Humerus > Proximal Femur. * **Fallen Leaf Sign:** Pathognomonic for UBC after a fracture. * **Treatment:** Observation or aspiration/injection of corticosteroids (Methylprednisolone). Surgery is reserved for large, weight-bearing lesions. * **Active vs. Latent:** A cyst is "active" if it is adjacent to the growth plate and "latent" if bone growth has moved the plate away from the cyst.

Q: Septic arthritis most commonly affects which joint in infants?

Hip joint. **Explanation:** In infants and children, the **hip joint** is the most common site for septic arthritis. The primary anatomical reason for this is the **intra-articular location of the metaphysis**. In the proximal femur, the growth plate (epiphysis) is located within the joint capsule. Because the metaphyseal blood vessels (transphyseal vessels) are patent in infants under one year of age, a hematogenous infection (osteomyelitis) in the metaphysis can easily breach the thin cortex and spread directly into the joint space, leading to septic arthritis. **Analysis of Options:** * **Hip Joint (Correct):** Due to the high vascularity of the proximal femur and the intracapsular metaphysis, it remains the most frequent site. It is a surgical emergency because increased intra-articular pressure can tamponade blood flow to the femoral head, leading to avascular necrosis (AVN). * **Neck:** This is not a joint commonly associated with septic arthritis; infections here usually manifest as discitis or vertebral osteomyelitis. * **Elbow and Shoulder Joints:** While these joints also have intracapsular metaphyses and can be affected, they occur much less frequently than the hip and knee in the pediatric population. **NEET-PG High-Yield Pearls:** * **Most common organism:** *Staphylococcus aureus* (overall). In neonates, consider Group B Streptococcus and Gram-negative bacilli. * **Kocher’s Criteria:** Used to differentiate septic arthritis from transient synovitis (1. Non-weight bearing, 2. ESR >40 mm/hr, 3. Fever >38.5°C, 4. WBC >12,000/mm³). * **Position of Ease:** The hip is typically held in **flexion, abduction, and external rotation** (maximum joint volume) to minimize pain. * **Diagnosis:** Ultrasound is the initial investigation of choice to detect joint effusion; **joint aspiration** is the gold standard for diagnosis.

Q: A solitary bone cyst is most common in which anatomical location?

Upper end of humerus. **Explanation:** A **Solitary Bone Cyst (SBC)**, also known as a Unicameral Bone Cyst, is a benign, fluid-filled cavity most commonly found in the pediatric population (typically 5–15 years). **Why the Upper End of Humerus is Correct:** The most common site for SBC is the **proximal humerus (upper end)**, followed closely by the **proximal femur**. These cysts typically originate near the epiphyseal plate (metaphysis) and "migrate" toward the diaphysis as the bone grows. They are often asymptomatic until discovered incidentally or when they present as a **pathological fracture** following minor trauma. **Analysis of Incorrect Options:** * **Lower end of humerus:** This is an uncommon site for primary bone tumors or cysts; most humeral lesions favor the proximal end. * **Upper end of fibula:** This is a classic site for **Osteochondromas** or **Giant Cell Tumors (GCT)** in adults, but not for SBC. * **Lower end of femur:** While the distal femur is the most common site for many bone tumors (like Osteosarcoma and GCT) due to rapid growth, it is less common for SBC compared to the proximal humerus. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Sign:** The **"Fallen Leaf Sign"** is pathognomonic for SBC, representing a fractured cortical fragment that has settled at the bottom of the fluid-filled cyst. * **Location:** Always metaphyseal and centrally located (unlike Aneurysmal Bone Cysts, which are often eccentric). * **Treatment:** Observation, steroid injections (methylprednisolone), or curettage and bone grafting if the risk of fracture is high. * **Age Group:** Primarily affects children and adolescents (80% occur in the first two decades of life).

Q: Needle aspiration of a central bone lesion is useful?

To rule out a vascular lesion. **Explanation:** In the management of central bone lesions (especially in the jaw or long bones), **needle aspiration** is a mandatory preliminary step before performing an incisional biopsy or curettage. **1. Why Option A is correct:** The primary clinical objective of aspiration is to **rule out a vascular lesion**, such as a central hemangioma or an arteriovenous malformation (AVM). If a surgeon inadvertently performs an incisional biopsy on a high-flow vascular lesion, it can lead to **uncontrollable, life-threatening hemorrhage**. Obtaining a "positive aspirate" (blood) alerts the clinician to perform further imaging like angiography rather than proceeding to surgery. **2. Why other options are incorrect:** * **Option B:** The thickness of the buccal plate is assessed via clinical palpation or radiographic imaging (CBCT/CT), not by needle aspiration. * **Option C:** While a traumatic bone cyst may yield a straw-colored fluid or be empty (air), aspiration is not the definitive diagnostic tool; surgical exploration revealing an empty cavity is the gold standard. * **Option D:** Feeling root surfaces is a function of periodontal probing or surgical visualization, not aspiration. **Clinical Pearls for NEET-PG:** * **Aspiration Findings:** * *Straw-colored fluid:* Suggestive of a dentigerous cyst or radicular cyst. * *Creamy/Cheesy material:* Suggestive of Odontogenic Keratocyst (OKC). * *Bright red blood:* Suggestive of Hemangioma or Aneurysmal Bone Cyst (ABC). * **Rule of Thumb:** Always "aspirate before you operate" on any radiolucent lesion to avoid "death on the operating table" from exsanguination.

Q: What is the treatment for an idiopathic bone cavity?

Opening and inducing bleeding by scraping. ### Explanation **Idiopathic Bone Cavity**, also known as a **Simple Bone Cyst (SBC)** or Unicameral Bone Cyst, is a fluid-filled pseudocyst (lacking an epithelial lining) typically found in the metaphyseal region of long bones in children. **1. Why Option A is Correct:** The primary goal of treatment is to initiate a healing response. The "cavity" is essentially a stagnant area where bone remodeling has ceased. By **opening the cyst and scraping the walls (curettage)**, the surgeon disrupts the inactive lining and **induces bleeding**. This hemorrhage introduces osteoprogenitor cells and growth factors into the cavity, which eventually leads to the formation of new bone and the obliteration of the cyst. **2. Why the Other Options are Incorrect:** * **B. Marsupialization:** This technique is used for cysts in soft tissues or the jaw (like odontogenic cysts) to relieve pressure, but it is not a standard orthopedic procedure for long bone cysts. * **C. Enucleation:** This implies removing a distinct sac or lining. Since an idiopathic bone cavity lacks a true epithelial lining (it is a "pseudocyst"), there is no "sac" to enucleate. * **D. No treatment is required:** While some small, asymptomatic cysts may be observed, most require intervention if they are large or at risk of **pathological fracture**, which is the most common presentation. **3. NEET-PG Clinical Pearls:** * **Classic Sign:** The **"Fallen Leaf Sign"** on X-ray (a fracture fragment settling at the bottom of the fluid-filled cyst). * **Common Site:** Proximal humerus (most common), followed by the proximal femur. * **Pathology:** It is a "true" cyst in appearance but a "pseudocyst" histologically because it lacks an epithelial lining. * **Alternative Treatments:** Aspiration and injection of **Methylprednisolone** or bone marrow aspirate are also high-yield management options.

Q: Shepherd's crook deformity is characteristically seen in which of the following conditions?

Fibrous dysplasia. **Explanation:** **Fibrous Dysplasia** is the correct answer. This condition is a developmental anomaly where normal bone is replaced by fibrous tissue and immature, woven bone (often described as "Chinese-letter" patterns on histology). The **Shepherd’s crook deformity** occurs due to repeated microfractures in the weakened, dysplastic bone of the proximal femur. Over time, the progressive bowing leads to a coxa vara deformity, resembling the curved staff used by a shepherd. This is most commonly seen in the polyostotic form of the disease and may be associated with McCune-Albright syndrome. **Analysis of Incorrect Options:** * **Non-ossifying fibroma (NOF):** This is a common, asymptomatic, benign bone lesion in children, usually found in the metaphysis of long bones. It typically regresses spontaneously and does not cause gross bony deformities like Shepherd’s crook. * **Adamantinoma:** A rare, low-grade malignant tumor most commonly found in the mid-shaft of the tibia. While it can cause anterior bowing (soap-bubble appearance), it is not associated with the specific proximal femoral deformity described. * **Fibrous cortical defect:** This is essentially a smaller version of NOF (less than 3 cm). It is a cortical "niche" that is usually an incidental finding and does not weaken the bone enough to cause major structural bowing. **Clinical Pearls for NEET-PG:** * **Radiological Sign:** "Ground-glass" appearance of the bone matrix. * **McCune-Albright Syndrome:** Triad of Polyostotic fibrous dysplasia, Café-au-lait spots (Coast of Maine borders), and precocious puberty. * **Mazabraud Syndrome:** Fibrous dysplasia associated with soft tissue intramuscular myxomas. * **Treatment:** Bisphosphonates can help with bone pain; surgery (medullary nailing) is required for significant deformities or fractures.

Q: Which one of the following statements is true about osteoclastoma?

The most common location is subarticular.. **Explanation:** **Osteoclastoma**, also known as **Giant Cell Tumor (GCT)**, is a locally aggressive primary bone tumor typically occurring in young adults (20–40 years) after epiphyseal closure. 1. **Why Option B is Correct:** The hallmark of GCT is its **eccentric, epiphyseal** location. Once the growth plate closes, the tumor extends to the end of the bone, reaching the **subarticular** (subchondral) surface. This is a classic radiological and pathological feature used to differentiate it from other bone tumors. 2. **Why Other Options are Incorrect:** * **Option A:** GCT is primarily an **epiphyseal** tumor. While it may involve the metaphysis as it grows, its origin and characteristic location are the epiphysis. In contrast, most primary bone tumors like Osteosarcoma arise in the metaphysis. * **Option C:** The treatment of choice is **surgical**, typically **extended curettage** with the use of adjuvants (like liquid nitrogen or phenol) and bone grafting/bone cement (PMMA). Radiation therapy is reserved only for inoperable cases (e.g., certain spinal tumors) due to the risk of malignant transformation. * **Option D:** **Sun-ray spiculation** (periosteal reaction) is a feature of **Osteosarcoma**. GCT typically shows a **"Soap-bubble appearance"** on X-ray due to fine bony trabeculations and lacks a significant periosteal reaction. **High-Yield Clinical Pearls for NEET-PG:** * **Commonest Site:** Around the knee (Distal femur > Proximal tibia). * **Pathology:** Characterized by multinucleated giant cells (osteoclast-like) scattered among mononuclear stromal cells. Note: The **stromal cells** are the actual neoplastic component. * **Campanacci Staging:** Used to grade the severity of GCT based on radiology. * **Denosumab:** A monoclonal antibody against RANKL used in the medical management of giant cell tumors.

Q: Which of the following tumors is the most chemoresistant?

Malignant fibrous histiocytoma. ### Explanation The correct answer is **Malignant Fibrous Histiocytoma (MFH)**, now more commonly classified as **Undifferentiated Pleomorphic Sarcoma (UPS)**. #### 1. Why Malignant Fibrous Histiocytoma is Correct MFH/UPS is a high-grade soft tissue and bone sarcoma characterized by extreme cellular pleomorphism and a lack of a specific line of differentiation. Among the options provided, it is notorious for its **poor response to chemotherapy**. While multi-agent chemotherapy (like Doxorubicin and Ifosfamide) is often used as an adjuvant to surgery, the survival benefit is significantly lower compared to other sarcomas. Its primary treatment remains wide surgical excision, as it is considered relatively **chemoresistant and radioresistant**. #### 2. Why the Other Options are Incorrect * **Osteosarcoma:** This is a **chemosensitive** tumor. The introduction of neoadjuvant chemotherapy (MAP protocol: Methotrexate, Adriamycin, Platinum) revolutionized its prognosis, increasing the 5-year survival rate from 20% to nearly 70%. * **Embryonal Rhabdomyosarcoma:** This is highly **chemosensitive**. Chemotherapy is a cornerstone of management (VAC regimen: Vincristine, Actinomycin-D, Cyclophosphamide), often leading to significant tumor shrinkage. * **Synovial Sarcoma:** While aggressive, it is considered **moderately chemosensitive**, particularly to Ifosfamide-based regimens, unlike the relative resistance seen in MFH. #### 3. NEET-PG High-Yield Pearls * **Most Radiosensitive Bone Tumor:** Ewing’s Sarcoma. * **Most Chemosensitive Bone Tumor:** Ewing’s Sarcoma (followed by Osteosarcoma). * **Tumor with "Storiform" Pattern on Histology:** Malignant Fibrous Histiocytoma. * **Sunray Appearance/Codman’s Triangle:** Classic radiological signs of Osteosarcoma. * **Ground Glass Appearance:** Fibrous Dysplasia.

Q: Peak incidence of osteosarcoma occurs at which decade of life?

2nd decade. **Explanation:** **Osteosarcoma** is the most common primary malignant bone tumor in children and adolescents. The peak incidence occurs in the **2nd decade of life (10–20 years)**. **Why the 2nd decade is correct:** This peak coincides with the **adolescent growth spurt**. Osteosarcoma typically arises in the metaphyseal region of long bones (most commonly the distal femur, followed by the proximal tibia and proximal humerus), where there is maximum osteoblastic activity and rapid bone turnover. The high rate of cell division during this period increases the likelihood of oncogenic mutations. **Analysis of Incorrect Options:** * **3rd decade:** While cases occur, the incidence drops significantly after skeletal maturity is reached. * **5th and 6th decades:** These represent the **secondary peak** of osteosarcoma. When osteosarcoma occurs in older adults, it is usually not "primary" but secondary to pre-existing conditions such as **Paget’s disease of bone**, post-radiation therapy, or bone infarcts. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Characteristic features include the **Sunray/Sunburst appearance** (due to spiculated periosteal reaction) and **Codman’s triangle** (elevation of the periosteum). * **Site:** Most common site is the **distal femur** (around the knee). * **Metastasis:** It spreads primarily via the hematogenous route, most commonly to the **lungs** (skip lesions may also be present in the same bone). * **Biomarker:** Serum **Alkaline Phosphatase (ALP)** levels are often elevated and serve as a marker for prognosis and treatment response. * **Treatment:** The standard of care is **Neoadjuvant chemotherapy** followed by limb-salvage surgery and postoperative chemotherapy.

Question 1

What is the most common bone cancer among young men?

Accepted Answer

Osteosarcoma

Answer

Chondrosarcoma

Answer

Ewing sarcoma

Answer

Giant cell tumor

Question 2

A 10-year-old boy presents with a fracture of the humerus. X-ray reveals a symmetric radiolytic lesion at the upper end of the right humerus, with a similar lesion present on the left humerus. What is the likely pathology?

Accepted Answer

Unicameral bone cyst

Answer

Osteosarcoma

Answer

Osteoclastoma

Answer

Aneurysmal bone cyst

Question 3

Septic arthritis most commonly affects which joint in infants?

Accepted Answer

Hip joint

Answer

Neck

Answer

Elbow joint

Answer

Shoulder joint

Question 4

A solitary bone cyst is most common in which anatomical location?

Accepted Answer

Upper end of humerus

Answer

Lower end of humerus

Answer

Upper end of fibula

Answer

Lower end of femur

Question 5

Needle aspiration of a central bone lesion is useful?

Accepted Answer

To rule out a vascular lesion

Answer

To determine the thickness of the buccal plate

Answer

To diagnose a traumatic bone cyst

Answer

To feel root surfaces

Question 6

What is the treatment for an idiopathic bone cavity?

Accepted Answer

Opening and inducing bleeding by scraping

Answer

Marsupialization

Answer

Enucleation

Answer

No treatment is required

Question 7

Shepherd's crook deformity is characteristically seen in which of the following conditions?

Accepted Answer

Fibrous dysplasia

Answer

Non-ossifying fibroma

Answer

Adamantinoma

Answer

Fibrous cortical defect

Question 8

Which one of the following statements is true about osteoclastoma?

Accepted Answer

The most common location is subarticular.

Answer

It most commonly arises from the metaphysis.

Answer

The treatment of choice is radiation therapy.

Answer

Sun-ray spiculation is seen on X-ray.

Question 9

Which of the following tumors is the most chemoresistant?

Accepted Answer

Malignant fibrous histiocytoma

Answer

Synovial sarcoma

Answer

Osteosarcoma

Answer

Embryonal rhabdomyosarcoma

Question 10

Peak incidence of osteosarcoma occurs at which decade of life?

Accepted Answer

2nd decade

Answer

3rd decade

Answer

5th decade

Answer

6th decade

Bone Tumors — MCQs

Bone Tumors — MCQs

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