Bone Tumors — MCQs

Bone Tumors Indian Medical PG Practice Questions and MCQs

Question 51: Hyperglycemia is associated with which of the following conditions?

A. Multiple Myeloma
B. Ewing's sarcoma
C. Osteosarcoma (Correct Answer)
D. Chondrosarcoma

Explanation: **Explanation:** **1. Why Osteosarcoma is the Correct Answer:** The association between **Osteosarcoma** and **Hyperglycemia** (or impaired glucose tolerance) is a classic, high-yield observation in orthopedic oncology. Studies have shown that a significant percentage of patients with Osteosarcoma exhibit abnormal glucose tolerance tests and **insulin resistance**. While the exact pathophysiology remains a subject of research, it is hypothesized that the tumor cells may produce substances that interfere with insulin sensitivity or that the metabolic demands of this highly aggressive malignancy alter systemic glucose homeostasis. **2. Analysis of Incorrect Options:** * **Multiple Myeloma:** This is associated with **Hypercalcemia**, renal failure, and anemia (CRAB criteria), but not specifically with hyperglycemia. * **Ewing’s Sarcoma:** This is a small round blue cell tumor characterized by the t(11;22) translocation. While it causes systemic symptoms like fever and elevated ESR (mimicking osteomyelitis), it has no known link to glucose metabolism. * **Chondrosarcoma:** This is a malignant cartilage-forming tumor typically seen in older adults. It is not associated with systemic metabolic derangements like hyperglycemia. **3. NEET-PG High-Yield Clinical Pearls:** * **Osteosarcoma:** Most common primary malignant bone tumor in children/adolescents. Look for **Sunray appearance** and **Codman’s triangle** on X-ray. It most commonly involves the **metaphysis** of the distal femur or proximal tibia. * **Metabolic Associations:** Apart from hyperglycemia, Osteosarcoma is also associated with markedly elevated levels of **Alkaline Phosphatase (ALP)** and **LDH**, which serve as prognostic markers. * **Genetic Link:** Strongly associated with mutations in the **RB1 gene** (Retinoblastoma) and **TP53 gene** (Li-Fraumeni syndrome).

Question 52: What is the most common site of metastases of osteosarcoma?

A. Liver
B. Spleen
C. Lymph nodes
D. Lung (Correct Answer)

Explanation: **Explanation:** **1. Why Lung is the Correct Answer:** Osteosarcoma is a highly malignant primary bone tumor characterized by the production of osteoid. Its primary mode of spread is **hematogenous** (via the bloodstream). Because the venous drainage from the limbs (where most osteosarcomas occur) passes directly into the systemic circulation and reaches the pulmonary capillary bed first, the **lungs** are the most common site of distant metastasis. Approximately 80% of patients who develop metastatic disease will have pulmonary involvement. These metastases often appear as "cannonball" lesions on imaging and can undergo ossification. **2. Why Other Options are Incorrect:** * **Liver and Spleen (A & B):** While osteosarcoma can spread to solid abdominal organs, this is rare and typically occurs only in the very late, terminal stages of disseminated disease. * **Lymph Nodes (C):** Unlike carcinomas, sarcomas (including osteosarcoma) rarely spread via the lymphatic system. Only about 3-5% of osteosarcoma cases show regional lymph node involvement. (Note: Exceptions among sarcomas that *do* spread to lymph nodes include Rhabdomyosarcoma, Clear cell sarcoma, and Epithelioid sarcoma). **3. Clinical Pearls for NEET-PG:** * **Skip Metastasis:** This refers to a second smaller lesion within the same bone or across a joint, occurring in the same limb. It indicates a poor prognosis. * **Investigation of Choice:** For the primary lesion, **MRI** is preferred to assess local extent. For detecting lung metastases, a **High-Resolution CT (HRCT) of the Chest** is the gold standard. * **Prognostic Factor:** The presence of lung metastasis at the time of diagnosis is the most significant negative prognostic factor. * **Sunray Appearance/Codman’s Triangle:** Classic radiological signs of osteosarcoma due to periosteal reaction.

Question 53: Which of the following is NOT true about diaphyseal aclasia?

A. It is multiple hereditary exostosis.
B. It is autosomal recessive. (Correct Answer)
C. It is associated with Madelung deformity.
D. The exostoses arise from the metaphysis.

Explanation: **Explanation:** **Diaphyseal Aclasia**, also known as **Multiple Hereditary Exostoses (MHE)**, is a genetic condition characterized by the growth of multiple osteochondromas. 1. **Why Option B is the correct answer (The False Statement):** Diaphyseal aclasia is an **Autosomal Dominant** condition, not recessive. It is primarily caused by mutations in the **EXT1** (Chromosome 8) or **EXT2** (Chromosome 11) genes, which are involved in the synthesis of heparan sulfate. 2. **Analysis of other options:** * **Option A:** It is synonymous with Multiple Hereditary Exostosis. The term "diaphyseal aclasia" refers to the failure of normal remodeling of the shaft (diaphysis) during growth. * **Option C:** It is frequently associated with **Madelung deformity** (shortening/bowing of the radius with dorsal subluxation of the distal ulna) and other growth disturbances like coxa valga and limb length discrepancy. * **Option D:** Although the name suggests "diaphyseal," the exostoses actually arise from the **metaphysis** near the growth plate. As the bone grows, they appear to migrate toward the diaphysis. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant (Most common skeletal dysplasia). * **Malignant Transformation:** There is a **1–5% risk** of transformation into **Chondrosarcoma** (suspect if there is sudden pain or a cartilage cap thickness >2 cm in adults). * **Direction of Growth:** The exostoses always grow **away from the joint** (the "fleeing from the knee" and "seeking the elbow" rule). * **Histology:** Characterized by a benign cartilaginous cap covering a bony stalk that is continuous with the marrow cavity of the host bone.

Question 54: Which of the following conditions is least likely to present as an acentric osteolytic lesion?

A. Aneurysmal bone cyst
B. Giant cell tumor
C. Fibrous cortical defect
D. Simple bone cyst (Correct Answer)

Explanation: **Explanation:** The key to solving this question lies in understanding the **location** of the lesion within the transverse plane of the bone. **1. Why Simple Bone Cyst (SBC) is the correct answer:** A Simple Bone Cyst (also known as a Unicameral Bone Cyst) is classically a **centrally located**, symmetric, radiolucent lesion. It typically occurs in the metaphyseal region of long bones (most commonly the proximal humerus and femur). As the bone grows, the cyst may appear to move toward the diaphysis, but it maintains its central orientation. A characteristic radiographic finding is the "Fallen Leaf sign" following a pathological fracture. **2. Analysis of Incorrect Options (Acentric Lesions):** * **Aneurysmal Bone Cyst (ABC):** These are characteristically **eccentric (acentric)**, expansile, "soap-bubble" lesions that often cause cortical thinning and "ballooning" of the bone. * **Giant Cell Tumor (GCT):** GCTs are typically **eccentric** and subarticular (extending to the subchondral plate). They occur in the epiphysis after the physis has closed. * **Fibrous Cortical Defect (FCD):** As the name suggests, these are small, cortical-based lesions. They are located **peripherally/eccentrically** within the metaphyseal cortex and are usually asymptomatic incidental findings in children. **High-Yield Clinical Pearls for NEET-PG:** * **Central Lesions:** Simple Bone Cyst, Enchondroma (usually central in small bones). * **Eccentric Lesions:** ABC, GCT, Osteosarcoma, Fibrous Dysplasia, Non-Ossifying Fibroma (NOF). * **Epiphyseal Lesions:** GCT (after plate closure), Chondroblastoma (before plate closure). * **Diaphyseal Lesions:** Ewing’s Sarcoma, Osteoid Osteoma, Adamantinoma. * **Soap-bubble appearance:** Classically seen in GCT and ABC.

Question 55: What is the commonest true benign tumor of bone?

A. Osteoblastoma
B. Chondroblastoma
C. Osteoid osteoma (Correct Answer)
D. Giant Cell Tumor (GCT)

Explanation: ### Explanation **Correct Answer: C. Osteoid osteoma** **Why it is correct:** Osteoid osteoma is considered the **most common true benign bone tumor**. While Osteochondroma is technically more frequent, it is pathologically classified as a developmental anomaly (physeal dysplasia) rather than a true neoplasm. Osteoid osteoma typically presents in the 2nd decade of life, most commonly in the femur or tibia. It is characterized by a small radiolucent **nidus** (less than 2 cm) surrounded by dense reactive sclerosis. **Why the other options are incorrect:** * **A. Osteoblastoma:** Often called a "giant osteoid osteoma" (nidus >2 cm), it is much rarer. It primarily affects the posterior elements of the spine and lacks the characteristic nocturnal pain relieved by NSAIDs. * **B. Chondroblastoma:** A rare benign cartilaginous tumor. Its distinguishing feature is its **epiphyseal** location in young patients (skeletally immature), but it is far less common than osteoid osteoma. * **C. Giant Cell Tumor (GCT):** While common, GCT is classified as a **locally aggressive** tumor rather than a simple "true benign" tumor. It occurs in the epiphysis of skeletally mature adults (20–40 years) and has a high recurrence rate. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** Severe nocturnal pain that is **dramatically relieved by Aspirin or NSAIDs** (due to high prostaglandin levels in the nidus). * **Radiology:** "Nidus" with surrounding sclerosis. On bone scan, it shows the **"Double density sign."** * **Most common site:** Proximal Femur. * **Treatment:** Medical management with NSAIDs is first-line; if refractory, **Radiofrequency Ablation (RFA)** is the gold standard.

Question 56: According to Sillence classification of osteogenesis imperfecta, which is the most common and mildest form?

A. Type 1 (Correct Answer)
B. Type 2
C. Type 3
D. Type 4

Explanation: **Explanation:** Osteogenesis Imperfecta (OI), or "Brittle Bone Disease," is a genetic disorder characterized by defects in **Type 1 Collagen** synthesis. The **Sillence Classification** categorizes OI into four primary types based on clinical severity and genetic transmission. * **Type 1 (Correct Answer):** This is the **most common** and **mildest** form. It is inherited in an Autosomal Dominant (AD) pattern. Patients have a near-normal stature and minimal bone deformity. A classic high-yield feature is the presence of **distinct blue sclera** throughout life. Fractures typically occur during childhood but decrease after puberty. **Analysis of Incorrect Options:** * **Type 2:** This is the **most severe and lethal** form (Perinatal lethal). It results in stillbirth or death in early infancy due to extreme bone fragility and respiratory failure. * **Type 3:** This is the **most severe non-lethal** form. It is characterized by "progressive deforming" bones, short stature, and significant scoliosis. Sclera may be blue at birth but often turns white with age. * **Type 4:** This is of intermediate severity. It is similar to Type 1 but is distinguished by having **normal (white) sclera**. **NEET-PG High-Yield Pearls:** * **Genetic Defect:** Mutations in **COL1A1** and **COL1A2** genes. * **Clinical Triad:** Fragile bones, Blue sclera, and Early-onset Otosclerosis (conductive hearing loss). * **Radiological Sign:** "Zebra stripe sign" (seen in patients treated with cyclic Bisphosphonates). * **Wormian Bones:** Often seen on skull X-rays of OI patients.

Question 57: Osteochondroma is a disease of which part of the bone?

A. Metaphysis (Correct Answer)
B. Diaphysis
C. Epiphysis
D. Periosteum

Explanation: **Explanation:** **Osteochondroma** (also known as Exostosis) is the most common benign bone tumor. It is fundamentally a developmental anomaly rather than a true neoplasm. **1. Why Metaphysis is Correct:** Osteochondromas arise from the **metaphysis** of long bones, most commonly around the knee (distal femur and proximal tibia). The pathogenesis involves the displacement of a fragment of the **epiphyseal growth plate** toward the metaphysis. As the bone grows, this displaced cartilage continues to proliferate and ossify, creating a bony outgrowth (stalk) covered by a cartilaginous cap. Because it originates from the growth plate and moves away with longitudinal growth, it is always found in the metaphyseal region. **2. Why Other Options are Incorrect:** * **Diaphysis:** While the tumor may appear to move toward the shaft as the bone grows, its origin is never the primary diaphysis. Common diaphyseal tumors include Ewing’s Sarcoma and Adamantinoma. * **Epiphysis:** Tumors here are rare. The classic epiphyseal tumor is the Giant Cell Tumor (GCT) or Chondroblastoma. * **Periosteum:** Although the tumor is covered by periosteum, it does not originate from it; it is a growth of the underlying bone and cartilage. **3. High-Yield Clinical Pearls for NEET-PG:** * **Radiological Sign:** The pathognomonic feature is **corticomedullary continuity** (the cortex and medulla of the tumor are continuous with the host bone). * **Direction of Growth:** The tumor always grows **away from the joint** (the "pointing away" sign). * **Malignant Transformation:** Occurs in <1% of solitary cases but is higher in **Hereditary Multiple Exostoses (HME)**. A cartilage cap thickness **>2 cm** in adults suggests transformation to Chondrosarcoma. * **Genetic Association:** Mutations in **EXT1 and EXT2** genes.

Question 58: Osteosclerotic lesions are seen in all EXCEPT?

A. Multiple myeloma
B. Fluorosis
C. Spina-ventosa (Correct Answer)
D. Carcinoma prostate

Explanation: **Explanation:** The core concept of this question lies in distinguishing between **osteosclerotic** (bone-forming/dense) and **osteolytic** (bone-destroying/lucent) lesions. **Spina Ventosa** (Option C) is the correct answer because it is a manifestation of **Tuberculous Dactylitis**. It typically presents as an **expansile, osteolytic lesion** of the short tubular bones (metacarpals and phalanges) in children. The term "ventosa" refers to the "inflated with air" appearance caused by subperiosteal bone resorption and medullary destruction, making it a lucent rather than a sclerotic lesion. **Why the other options are incorrect:** * **Multiple Myeloma (Option A):** While classically known for "punched-out" lytic lesions, a rare variant called **POEMS syndrome** (Polyneuropathy, Organomegaly, Endocrinology, M-protein, Skin changes) is specifically associated with **osteosclerotic** myeloma. (Note: In standard NEET-PG contexts, if "POEMS" isn't mentioned, Myeloma is lytic; however, compared to Spina Ventosa, it is a recognized cause of sclerosis in specific syndromes). * **Fluorosis (Option B):** Chronic fluoride toxicity stimulates osteoblastic activity, leading to generalized **diffuse osteosclerosis**, particularly in the axial skeleton. * **Carcinoma Prostate (Option D):** This is the classic cause of **osteoblastic (sclerotic) metastases** in elderly males. **NEET-PG High-Yield Pearls:** * **Mnemonic for Sclerotic Bone Metastases:** "**P**rostate, **B**reast (can be mixed), **C**arcinoid, **L**ymphoma, **M**edullary CA Thyroid" (**P**eads **B**oys **C**an **L**ove **M**ath). * **Spina Ventosa:** Most common in the proximal phalanx of the index and middle fingers. * **Ivory Vertebra:** A single radiopaque (sclerotic) vertebra; common causes include Hodgkin’s Lymphoma, Paget’s Disease, and Prostatic Metastasis.

Question 59: On a 3-phase 99mTc-MDP bone scan, which of the following bone lesions will show the least osteoblastic activity?

A. Paget's disease
B. Osteoid Osteoma
C. Fibrous Dysplasia
D. Fibrous cortical defect (Correct Answer)

Explanation: ### Explanation The correct answer is **Fibrous cortical defect (D)**. **Understanding the Concept:** A 99mTc-MDP bone scan measures **osteoblastic activity** (bone formation) and **vascularity**. The tracer uptake depends on the rate of bone turnover. * **Fibrous cortical defect (FCD)**, also known as a non-ossifying fibroma (when >2cm), is a benign, "leave-me-alone" lesion. It consists of inactive fibrous tissue replacing bone. Because it is a quiescent, non-neoplastic developmental defect with no active bone remodeling or significant vascularity, it typically appears **"cold" or shows minimal uptake** on a bone scan. **Analysis of Incorrect Options:** * **Paget's Disease (A):** Characterized by intense, disorganized bone remodeling (both osteoclastic and osteoblastic). It shows the highest intensity of uptake ("marked hot scan") among all bone pathologies. * **Osteoid Osteoma (B):** A classic "hot" lesion. The nidus produces high levels of prostaglandins, leading to intense focal uptake. It often shows the "double density sign" on bone scans. * **Fibrous Dysplasia (C):** Although it is a fibrous lesion, it involves active replacement of normal bone with immature "woven" bone. This high metabolic turnover results in significant tracer uptake (usually very "hot"). **NEET-PG High-Yield Pearls:** 1. **"Cold" Lesions on Bone Scan:** Multiple myeloma (classic), Fibrous cortical defect, Bone infarct (early stage), and Anaplastic tumors. 2. **"Hot" Lesions:** Paget’s disease, Osteoid osteoma, Osteosarcoma, and healing fractures. 3. **Fibrous Cortical Defect:** Most common in the distal femur/proximal tibia of children; usually an incidental finding on X-ray (eccentric, cortical-based, lucent lesion with a sclerotic rim).

Question 60: What is the most abundant type of collagen found in bone?

A. Type I (Correct Answer)
B. Type II
C. Type III
D. Type IV

Explanation: **Explanation:** The correct answer is **Type I Collagen**. **1. Why Type I is Correct:** Bone is a specialized connective tissue composed of an organic matrix (35%) and inorganic mineral (65%). Approximately 90% of the organic matrix consists of **Type I collagen**. It provides the structural framework and tensile strength necessary for bone to resist fracture. It is synthesized by osteoblasts and forms the characteristic triple helix structure that undergoes mineralization with hydroxyapatite crystals. **2. Why Other Options are Incorrect:** * **Type II:** This is the primary collagen found in **hyaline and elastic cartilage**, as well as the vitreous humor of the eye. It is not a significant component of mature bone. * **Type III:** Also known as "reticulin," this type is found in **distensible tissues** like blood vessels, skin, and granulation tissue. It is often the first collagen synthesized during wound healing before being replaced by Type I. * **Type IV:** This type is unique because it does not form fibrils; instead, it forms a meshwork that constitutes the **basal lamina** (basement membrane). **3. NEET-PG Clinical Pearls:** * **Mnemonic:** Remember "Type **One** is in B**one**." * **Osteogenesis Imperfecta:** This "brittle bone disease" is caused by genetic mutations in the synthesis of Type I collagen. * **Scurvy:** Vitamin C deficiency leads to defective hydroxylation of proline and lysine residues, resulting in unstable Type I collagen and impaired bone formation. * **Type II** is found in the **Physeal (Growth) Plate**, specifically in the proliferative and hypertrophic zones.

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Classification of Bone Tumors

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Benign Bone Tumors

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Malignant Primary Bone Tumors

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Metastatic Bone Disease

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Tumor-Like Lesions of Bone

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Soft Tissue Tumors

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Evaluation and Staging of Bone Tumors

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Biopsy Principles

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Limb Salvage Surgery

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Amputation for Bone Tumors

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Adjuvant Therapies

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Surveillance and Follow-up

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Bone Tumors — MCQs

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