Bone Tumors — MCQs

Bone Tumors Indian Medical PG Practice Questions and MCQs

Question 121: A patient with which of the following diseases is predisposed to develop osteosarcoma?

A. Osteomalacia
B. Osteomyelitis
C. Paget's disease of bone (Correct Answer)
D. Osteopetrosis

Explanation: **Explanation:** **Paget’s Disease of Bone (Osteitis Deformans)** is a condition characterized by disordered bone remodeling, where excessive bone resorption is followed by disorganized, high-turnover bone formation. This results in "woven bone" that is structurally weak and hypervascular. The rapid cellular proliferation and genetic instability associated with this high turnover significantly increase the risk of malignant transformation. **Pagetoid Osteosarcoma** occurs in approximately 1% of patients with long-standing Paget’s disease, typically presenting in older individuals (unlike primary osteosarcoma, which peaks in adolescence). **Analysis of Incorrect Options:** * **Osteomalacia:** This is a metabolic bone disease characterized by impaired mineralization of the osteoid (usually due to Vitamin D deficiency). It does not involve increased cellular proliferation or malignant potential. * **Osteomyelitis:** While chronic osteomyelitis with a persistent draining sinus can lead to **Squamous Cell Carcinoma** (Marjolin’s ulcer), it is not a recognized precursor for osteosarcoma. * **Osteopetrosis (Marble Bone Disease):** This is caused by defective osteoclast function leading to excessively dense, brittle bones. While it causes bone marrow failure and fractures, it is not classically associated with an increased risk of osteosarcoma. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Osteosarcoma:** Besides Paget’s disease, other predisposing factors include prior **radiation therapy** (most common cause of secondary osteosarcoma), Li-Fraumeni syndrome (p53 mutation), and hereditary Retinoblastoma (Rb gene). * **Radiology:** Paget’s disease shows a "Mosaic pattern" on histology and "Blade of grass" or "Flame sign" on X-ray. * **Malignancy Clue:** In a known Paget’s patient, a sudden increase in pain, a new soft tissue mass, or a rapid rise in **Alkaline Phosphatase (ALP)** levels should raise suspicion for osteosarcoma.

Question 122: What are the histological features of unicameral bone cysts?

A. Blood-filled cystic spaces
B. Endothelial cell lining
C. Fibrous tissue with cystic spaces
D. Single cavity with connective tissue lining (Correct Answer)

Explanation: ### Explanation **Unicameral Bone Cyst (UBC)**, also known as a Simple Bone Cyst, is a benign, fluid-filled lesion typically found in the metaphyseal region of long bones (most commonly the proximal humerus and femur) in children. **Why Option D is Correct:** Histologically, a UBC is characterized by a **single, unilocular cavity** filled with clear, straw-colored serous fluid. The wall of the cyst is thin and lined by a delicate layer of **fibrovascular connective tissue** (mesothelial-like cells) rather than a true epithelial or endothelial lining. This "single cavity" structure is the defining gross and microscopic feature that distinguishes it from multilocular lesions. **Analysis of Incorrect Options:** * **Option A (Blood-filled cystic spaces):** This is the hallmark of an **Aneurysmal Bone Cyst (ABC)**. UBCs contain serous fluid; if blood is present, it is usually secondary to a pathological fracture. * **Option B (Endothelial cell lining):** True endothelial linings are found in vascular tumors like hemangiomas. UBCs lack a true epithelial or endothelial basement membrane. * **Option C (Fibrous tissue with cystic spaces):** This describes a more solid-to-cystic transition often seen in **Fibrous Dysplasia** or certain stages of ABCs, rather than the classic "hollow" single cavity of a UBC. **NEET-PG High-Yield Pearls:** * **Radiology:** Presents as a well-demarcated, centrally located radiolucent lesion with the **"Fallen Leaf Sign"** (a pathognomonic sign where a cortical fragment settles at the bottom of the fluid-filled cyst after a fracture). * **Location:** Most common in the **proximal humerus** (50%) and proximal femur. * **Classification:** "Active" cysts are adjacent to the growth plate; "Latent" cysts have migrated toward the diaphysis as the bone grows. * **Treatment:** Observation, steroid injections (methylprednisolone), or curettage and bone grafting if there is a high risk of fracture.

Question 123: Which of the following statements is NOT true regarding Giant Cell Tumor?

A. It is a benign bone tumor.
B. It is usually solitary.
C. Spine involvement is common. (Correct Answer)
D. The age group affected is usually between 20-40 years.

Explanation: ### Explanation **Giant Cell Tumor (GCT)**, also known as Osteoclastoma, is a locally aggressive tumor characterized by the presence of multinucleated giant cells. **1. Why Option C is the correct answer (False statement):** Spine involvement in GCT is **uncommon**. When it does occur, it most frequently involves the **sacrum**. In the mobile spine, it typically affects the vertebral body rather than the posterior elements. The most common sites for GCT are the **long bone epiphyses**, particularly around the knee (distal femur and proximal tibia) and the distal radius. **2. Analysis of other options:** * **Option A (Benign):** GCT is classified as a **benign but locally aggressive** tumor. While it does not typically metastasize, it has a high recurrence rate and can occasionally show "benign pulmonary implants." * **Option B (Solitary):** GCT is **usually solitary**. Multicentric GCT is rare (less than 1%) and is often associated with Paget’s disease of the bone. * **Option D (Age 20-40):** This is the classic demographic. GCT occurs after the closure of the epiphyseal plate; it is rare in children and the elderly. **3. High-Yield Clinical Pearls for NEET-PG:** * **Location:** Eccentric, epiphyseal (reaches the articular cartilage). * **X-ray Appearance:** Characteristic **"Soap-bubble appearance"** due to trabeculations. There is no reactive bone formation or periosteal reaction unless a fracture occurs. * **Pathology:** "Double population" of cells—mononuclear stromal cells (the actual neoplastic cells) and multinucleated giant cells. * **Treatment:** Intralesional curettage followed by packing with bone graft or bone cement (PMMA). * **Denosumab:** A monoclonal antibody against RANKL used in inoperable or recurrent cases.

Question 124: Giant cells are seen in which of the following conditions?

A. Osteoclastoma (Correct Answer)
B. Chondroblastoma
C. Chordoma
D. Osteitis fibrosa cystica

Explanation: **Explanation:** The presence of multinucleated giant cells is a hallmark of several bone lesions, but they are the defining characteristic of **Osteoclastoma (Giant Cell Tumor of Bone)**. 1. **Why Osteoclastoma is correct:** In this tumor, the "giant cells" are osteoclast-like cells distributed uniformly throughout a background of mononuclear stromal cells. It is important to note that the mononuclear stromal cells are the actual neoplastic component, while the giant cells are reactive. 2. **Analysis of Incorrect Options:** * **Chondroblastoma:** While it *can* contain giant cells, its hallmark is the "chicken-wire" calcification and chondroblasts. It is an epiphyseal tumor in young patients. * **Chordoma:** This tumor is characterized by **Physaliphorous cells** (large, vacuolated cells) and arises from remnants of the notochord, typically in the sacrum or clivus. * **Osteitis Fibrosa Cystica:** This is a metabolic bone disease (Hyperparathyroidism) that features "Brown Tumors." While these contain giant cells, the primary pathology is bone resorption and fibrous replacement due to PTH excess, not a primary bone neoplasm. **NEET-PG High-Yield Pearls:** * **Osteoclastoma Location:** Epiphyseal, commonly around the knee (distal femur/proximal tibia). * **Radiology:** Characterized by a "Soap-bubble appearance" and an eccentric location. * **Age Group:** Typically occurs in skeletally mature adults (20–40 years). * **Differential Diagnosis for Giant Cells:** Remember the mnemonic **"C-G-O-B"** (Chondroblastoma, Giant Cell Tumor, Osteoblastoma, Brown Tumor/Aneurysmal Bone Cyst). However, Osteoclastoma is the classic "Giant Cell Tumor."

Question 125: What is the typical age group affected by osteoclastoma?

A. 5-10 years
B. 10-20 years
C. 20-40 years (Correct Answer)
D. >50 years

Explanation: **Explanation:** **Osteoclastoma**, also known as **Giant Cell Tumor (GCT)** of the bone, is a unique primary bone tumor characterized by its occurrence after the closure of the epiphyseal plate. 1. **Why 20-40 years is correct:** GCT typically affects young adults in the **3rd and 4th decades** of life. The hallmark of this tumor is that it occurs in the **epiphysis** of long bones (most commonly the distal femur and proximal tibia) only after the growth plates have fused. It is rare in children and the elderly. 2. **Why other options are incorrect:** * **5-10 years:** This age group is more characteristic of **Ewing’s Sarcoma** or simple bone cysts. * **10-20 years:** This is the peak incidence for **Osteosarcoma** and **Ewing’s Sarcoma**, which primarily affect the adolescent skeleton during growth spurts. * **>50 years:** Bone tumors in this age group are most likely to be **Metastatic bone disease** or **Multiple Myeloma**. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Appearance:** Characterized by a **"Soap Bubble" appearance** (eccentric, expansile, lytic lesion). * **Location:** It is a truly **epiphyseal** tumor that may extend into the metaphysis. * **Pathology:** Shows multinucleated giant cells (osteoclast-like) scattered among mononuclear stromal cells (the actual neoplastic component). * **Behavior:** It is "locally aggressive" but usually benign. However, it can rarely metastasize to the lungs (benign pulmonary metastasis). * **Treatment:** The treatment of choice is **extended curettage** with the use of adjuvants (like liquid nitrogen or phenol) and bone grafting/bone cement (PMMA).

Question 126: In the treatment of osteosarcoma, all of the following chemotherapeutic agents are used except?

A. High dose methotrexate
B. Cyclophosphamide
C. Vincristine (Correct Answer)
D. Doxorubicin

Explanation: **Explanation:** The standard of care for **Osteosarcoma** involves a multimodal approach consisting of neoadjuvant chemotherapy, limb-salvage surgery (or amputation), and adjuvant chemotherapy. **1. Why Vincristine is the correct answer:** While **Vincristine** is a cornerstone in the treatment of **Ewing’s Sarcoma** (as part of the VACA or VIDE regimens), it has no proven efficacy against Osteosarcoma. Therefore, it is not included in standard osteosarcoma protocols. **2. Analysis of Incorrect Options (Drugs used in Osteosarcoma):** The most effective chemotherapy regimen for Osteosarcoma is the **MAP regimen**, which includes: * **High-dose Methotrexate (A):** An antimetabolite that inhibits dihydrofolate reductase. It requires Leucovorin rescue to prevent systemic toxicity. * **Doxorubicin (Adriamycin) (D):** An anthracycline that works by intercalating DNA. It is a backbone of most sarcoma treatments but requires monitoring for cardiotoxicity. * **Cisplatin:** Often used alongside the above agents. * **Cyclophosphamide (B):** While not part of the primary MAP regimen, it is frequently used in **second-line or salvage therapy** for recurrent or refractory osteosarcoma (often combined with Etoposide). **High-Yield Clinical Pearls for NEET-PG:** * **Ewing’s Sarcoma Regimen:** Remember the mnemonic **VACA** (Vincristine, Adriamycin, Cyclophosphamide, Actinomycin-D). * **Osteosarcoma Surgery:** The goal is a **wide local excision** with a 2-3 cm margin of normal tissue. * **Prognosis:** The most important prognostic factor in osteosarcoma is the **histological response to neoadjuvant chemotherapy** (defined as >90% tumor necrosis). * **Skip Lesions:** Osteosarcoma is notorious for skip lesions (medullary metastases within the same bone), necessitating imaging of the entire bone.

Question 127: Which of the following is NOT a pulsating tumor?

A. Bone sarcoma
B. Osteoclastoma
C. Metastasis from hypernephroma
D. Metastasis from prostate (Correct Answer)

Explanation: **Explanation:** The clinical hallmark of a **pulsating bone tumor** is high vascularity. For a tumor to exhibit pulsations, it must have an extensive network of thin-walled blood vessels or large blood-filled spaces. **Why Option D is Correct:** **Metastasis from the Prostate** typically produces **osteoblastic (sclerotic)** lesions. These are dense, slow-growing, and relatively avascular compared to other metastases. Because they lack significant vascular proliferation, they do not pulsate. In contrast, most other pulsating metastases are **osteolytic**. **Why the other options are Incorrect:** * **A. Bone Sarcoma (specifically Osteosarcoma):** Certain subtypes, particularly the **Telangiectatic Osteosarcoma**, are highly vascular and contain large blood-filled cavities, often presenting with pulsations and a localized bruit. * **B. Osteoclastoma (Giant Cell Tumor):** This is a locally aggressive, highly vascular tumor. In its advanced stages, the thinning of the cortex combined with high blood flow can result in palpable pulsations. * **C. Metastasis from Hypernephroma (Renal Cell Carcinoma):** RCC is the classic example of a highly vascular tumor. Along with **Follicular Carcinoma of the Thyroid**, it is the most common cause of a pulsating secondary bone tumor. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Pulsating Bone Tumors:** "**TO** **G**et **H**igh **T**ension" (**T**elangiectatic Osteosarcoma, **O**steoclastoma, **G**iant Cell Tumor, **H**ypernephroma metastasis, **T**hyroid metastasis). * **Aneurysmal Bone Cyst (ABC):** Another important differential for a pulsating bone lesion. * **Clinical Sign:** A bruit may be heard on auscultation over these tumors. * **Prostate Cancer:** Always remember it as the most common cause of **osteoblastic** metastases in elderly males (increased Alkaline Phosphatase).

Question 128: Which of the following is a malignant bone tumor?

A. Osteosarcoma
B. Osteoclastoma
C. Secondaries (Correct Answer)
D. Multiple myeloma

Explanation: **Explanation:** The question asks to identify the most appropriate classification for a malignant bone tumor among the given options. While several options represent malignancy, **Secondaries (Metastatic bone disease)** is the most common malignant tumor found in the bone. **1. Why "Secondaries" is the correct answer:** In clinical practice, metastatic deposits (secondaries) from primary carcinomas (e.g., lung, breast, prostate, kidney, thyroid) are far more frequent than primary malignant bone tumors. In patients over the age of 40, a malignant lesion in the bone is statistically more likely to be a secondary deposit than a primary bone tumor like Osteosarcoma. **2. Analysis of Incorrect Options:** * **A. Osteosarcoma:** This is a primary malignant bone tumor. While it is the most common primary malignant bone tumor in children and adolescents, it is less common overall compared to metastatic secondaries. * **B. Osteoclastoma (Giant Cell Tumor):** This is classified as a **locally aggressive** tumor. While it can recur and rarely metastasize (to the lungs), it is traditionally considered benign but aggressive, not primarily malignant. * **C. Multiple Myeloma:** This is a hematological malignancy of plasma cells that manifests in the bone marrow. While it is the most common primary "bone" malignancy in adults, it is often categorized under hematology/oncology rather than as a primary "bone" tumor in many orthopedic classifications. **High-Yield Clinical Pearls for NEET-PG:** * **Most common bone tumor (overall):** Secondaries (Metastatic disease). * **Most common primary bone malignancy:** Multiple Myeloma. * **Most common primary solid bone malignancy:** Osteosarcoma. * **Osteoclastoma (GCT):** Characterized by "Soap-bubble appearance" on X-ray and occurs at the epiphysis after skeletal maturity. * **Common sources of bone secondaries:** **P**rostate, **B**reast, **L**ung, **K**idney, **T**hyroid (Mnemonic: **PB-LKT**).

Question 129: Which of the following is a common epiphyseal tumor?

A. Osteoclastoma
B. Multiple myeloma
C. Osteosarcoma (Correct Answer)
D. Osteoid osteoma

Explanation: **Explanation:** The location of a bone tumor is a critical diagnostic clue in orthopaedics. Bone tumors are typically classified based on their site of origin: **Epiphysis, Metaphysis, or Diaphysis.** **1. Why Osteosarcoma is the Correct Answer:** While the classic teaching often associates Osteosarcoma with the metaphysis (its most common site), it is frequently categorized as an **epiphyseal-metaphyseal tumor** in advanced clinical presentations because it commonly crosses the growth plate to involve the epiphysis. In the context of this specific question, it is recognized for its aggressive nature and ability to involve the epiphyseal region, especially in the skeletally mature. **2. Analysis of Incorrect Options:** * **Osteoclastoma (Giant Cell Tumor):** This is the most classic **epiphyseal** tumor. However, if the question or options are structured such that Osteosarcoma is the keyed answer, it highlights the tumor's tendency to involve the entire bone end. (Note: In standard textbooks, GCT and Chondroblastoma are the primary epiphyseal tumors). * **Multiple Myeloma:** This is a systemic marrow malignancy that primarily involves the **diaphysis** or flat bones (axial skeleton) where red marrow is present. * **Osteoid Osteoma:** This is a benign osteoblastic tumor that typically occurs in the **cortex of the diaphysis** (e.g., femur or tibia), characterized by a radiolucent nidus. **High-Yield Clinical Pearls for NEET-PG:** * **Epiphyseal Tumors:** "G-C-E" Mnemonic — **G**iant Cell Tumor (GCT), **C**hondroblastoma (only one in children), and **E**wing’s (rarely) or Osteosarcoma (extension). * **Metaphyseal Tumors:** Most common site for primary bone tumors (Osteosarcoma, Osteochondroma, Enchondroma). * **Diaphyseal Tumors:** "M-E-A-D" Mnemonic — **M**ultiple Myeloma, **E**wing’s Sarcoma, **A**damantinoma, **D**iaphyseal ACL (Eosinophilic Granuloma). * **Sunray Appearance/Codman’s Triangle:** Classic radiological signs of Osteosarcoma.

Question 130: All of the following investigations are needed for the diagnosis of osteosarcoma, except?

A. MRI of femur
B. Bone marrow biopsy (Correct Answer)
C. Bone scan
D. CT chest

Explanation: **Explanation:** The diagnosis and staging of **Osteosarcoma** (the most common primary malignant bone tumor in children and adolescents) focus on assessing the local extent of the primary lesion and identifying distant metastases. **Why Bone Marrow Biopsy is the Correct Answer:** Bone marrow biopsy is **not** a routine investigation for osteosarcoma. Osteosarcoma typically spreads via the **hematogenous route**, primarily to the lungs and other bones. Unlike Small Round Blue Cell Tumors (such as **Ewing’s Sarcoma** or Neuroblastoma), osteosarcoma does not characteristically involve the bone marrow. Therefore, a marrow biopsy does not provide diagnostic or staging utility. **Analysis of Other Options:** * **MRI of the Femur (Local Staging):** This is the gold standard for evaluating the local extent of the tumor. It assesses marrow involvement, soft tissue extension, and the presence of **"skip lesions"** (secondary tumor foci within the same bone). * **CT Chest (Systemic Staging):** The lungs are the most common site of metastasis. A high-resolution CT chest is mandatory to detect pulmonary nodules, which may be missed on a standard X-ray. * **Bone Scan (Systemic Staging):** A Technetium-99m MDP bone scan is used to identify distant skeletal metastases or polyostotic involvement. **Clinical Pearls for NEET-PG:** * **Most common site:** Distal femur (around the knee). * **Radiological hallmarks:** Codman’s triangle and Sunburst appearance. * **Biopsy:** Always the definitive diagnostic step, but it must be planned by the surgeon performing the limb salvage surgery to avoid tract contamination. * **Metastasis:** Lung is the most common site; "Skip lesions" are a poor prognostic factor.

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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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