Bone Tumors Practice Questions

Q: What is the characteristic location of Ewing's sarcoma?

Diaphysis. **Explanation:** **Ewing’s Sarcoma** is a highly malignant primary bone tumor typically seen in children and adolescents (5–15 years). The characteristic location is the **Diaphysis** (shaft) of long bones, most commonly the femur, tibia, and humerus. **Why Diaphysis is correct:** Ewing’s sarcoma originates from the marrow cavity (neuroectodermal origin). Unlike many other bone tumors that arise from the growth plate regions, Ewing’s has a predilection for the mid-shaft. The tumor cells permeate the Haversian canals, reaching the subperiosteal space and triggering a characteristic "onion-skin" periosteal reaction. **Why other options are incorrect:** * **Epiphysis:** This is a rare site for tumors. The classic "epiphyseal" tumors are Giant Cell Tumor (GCT) in adults and Chondroblastoma in children. * **Metaphysis:** This is the most common site for most primary bone tumors (e.g., Osteosarcoma, Osteochondroma, and Aneurysmal Bone Cyst) due to high metabolic activity and cell turnover. Ewing’s is a notable exception to this rule. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Classic "Onion-peel" appearance (concentric layers of new bone formation). * **Histology:** Small, round, blue cell tumor with PAS-positive (diastase sensitive) cytoplasm due to glycogen. * **Genetics:** Associated with **t(11;22)** translocation, leading to the **EWS-FLI1** fusion gene. * **Clinical Presentation:** Often mimics osteomyelitis (fever, raised ESR, local swelling, and pain). * **Markers:** CD99 (MIC-2) positive.

Q: Osteosarcoma originates from which type of cells?

Osteoblasts. **Explanation:** **1. Why Osteoblasts are correct:** Osteosarcoma is a primary malignant bone tumor characterized by the direct production of **osteoid** (immature bone) or bone by malignant cells. These malignant cells are mesenchymal in origin and differentiate into **osteoblasts**. Since osteoblasts are the cells responsible for bone formation, their neoplastic transformation leads to the uncontrolled production of mineralized and non-mineralized bone matrix, which is the hallmark histological feature of Osteosarcoma. **2. Why other options are incorrect:** * **Osteocytes:** These are mature bone cells trapped within the lacunae of the bone matrix. They are metabolically less active and do not typically undergo malignant transformation into Osteosarcoma. * **Chondrocytes:** These are cartilage-forming cells. Malignant transformation of these cells leads to **Chondrosarcoma**, not Osteosarcoma. * **Osteoclasts:** These are multinucleated giant cells responsible for bone resorption (derived from the monocyte-macrophage lineage). While "Giant Cell Tumors" (GCT) contain osteoclast-like cells, they are not the cell of origin for Osteosarcoma. **3. NEET-PG High-Yield Pearls:** * **Age Distribution:** Bimodal (10–20 years and >60 years associated with Paget’s disease). * **Location:** Most common site is the **metaphysis** of long bones (Distal femur > Proximal tibia). * **Radiology:** Classic findings include the **Sunburst appearance** (periosteal reaction) and **Codman’s triangle**. * **Genetic Association:** Strongly linked to mutations in the **RB1** (Retinoblastoma) and **TP53** (Li-Fraumeni syndrome) genes. * **Metastasis:** Spreads primarily via the bloodstream, most commonly to the **lungs** (skip lesions may also occur).

Q: What is the most common primary malignant bone tumor?

Multiple myeloma. **Explanation:** The correct answer is **Multiple Myeloma**. In the context of bone tumors, it is essential to distinguish between "primary malignant bone tumors" (which include hematological malignancies arising in the bone marrow) and "primary malignant non-hematopoietic bone tumors." 1. **Why Multiple Myeloma is correct:** Multiple myeloma is a plasma cell dyscrasia that arises within the bone marrow. Epidemiologically, it is the **most common primary malignancy of bone** overall. In NEET-PG, if the question does not specify "non-hematopoietic" or "matrix-forming," Multiple Myeloma remains the top choice. It typically affects adults over 50 years of age and presents with "punched-out" lytic lesions. 2. **Why the other options are incorrect:** * **Osteosarcoma:** This is the most common primary **non-hematopoietic** (or bone-forming) malignant bone tumor. It is the most common primary malignancy in children and adolescents, but second to Multiple Myeloma in the general population. * **Osteochondroma:** This is the most common **benign** bone tumor. It is a developmental outgrowth (exostosis) rather than a malignancy. * **Osteoclastoma (Giant Cell Tumor):** This is a "locally aggressive" tumor, usually considered benign but with potential for recurrence and rare metastasis. It is not the most common malignancy. **NEET-PG High-Yield Pearls:** * **Most common bone tumor overall:** Metastatic bone disease (Secondary). * **Most common primary bone malignancy:** Multiple Myeloma. * **Most common primary bone malignancy (excluding hematological):** Osteosarcoma. * **Most common benign bone tumor:** Osteochondroma. * **Age Factor:** If the patient is >40 years, think Metastasis or Multiple Myeloma; if <20 years, think Osteosarcoma or Ewing’s Sarcoma.

Q: What is the most common type of patellar bursitis?

Prepatellar bursitis. **Explanation:** **Prepatellar bursitis** is the most common type of patellar bursitis. It involves inflammation of the bursa located superficial to the patella, between the skin and the bone. This condition is classically known as **"Housemaid’s Knee"** because it is caused by repetitive friction or direct pressure from frequent kneeling. Due to its superficial location, it is highly susceptible to both chronic microtrauma and acute infection (septic bursitis). **Analysis of Incorrect Options:** * **Suprapatellar bursitis:** This involves the bursa located between the quadriceps tendon and the femur. It is actually an extension of the knee joint cavity; therefore, "bursitis" here usually manifests as a generalized knee joint effusion rather than an isolated bursal pathology. * **Infrapatellar bursitis:** This affects the bursae around the patellar ligament. **Deep infrapatellar bursitis** (between the ligament and tibia) and **superficial infrapatellar bursitis** (**"Clergyman’s Knee"**) occur less frequently than prepatellar involvement. * **Pes anserine bursitis:** Located on the medial aspect of the proximal tibia (at the insertion of Sartorius, Gracilis, and Semitendinosus), this causes medial knee pain but is anatomically distinct from the patellar bursae. **NEET-PG High-Yield Pearls:** * **Housemaid’s Knee:** Prepatellar bursitis (due to kneeling on all fours). * **Clergyman’s Knee:** Superficial infrapatellar bursitis (due to more upright kneeling/praying). * **Student’s Elbow:** Olecranon bursitis (the upper limb equivalent of prepatellar bursitis). * **Clinical Sign:** In prepatellar bursitis, the swelling is localized and superficial to the patella, and knee joint range of motion is usually preserved (unlike intra-articular effusions).

Q: The differential diagnosis of a lesion, histologically resembling a giant cell tumor in the small bones of the hands or feet, includes all of the following except:

Fibrosarcoma. **Explanation:** The core of this question lies in identifying lesions that contain **Giant Cells** on histology, which can mimic a Giant Cell Tumor (GCT). **Why Fibrosarcoma is the Correct Answer:** Fibrosarcoma is a malignant tumor of mesenchymal origin characterized by a "herringbone" pattern of spindle-shaped fibroblasts. Crucially, it **does not typically contain multinucleated giant cells** as a primary histological feature. Therefore, it is not a standard differential diagnosis for a GCT-like lesion. **Analysis of Incorrect Options (Differential Diagnoses of GCT):** * **Aneurysmal Bone Cyst (ABC):** These are common in small bones and histologically show blood-filled spaces separated by fibrous septa containing numerous multinucleated giant cells. * **Osteosarcoma:** Specifically, the **Telangiectatic variant** of osteosarcoma contains large blood-filled spaces and numerous giant cells, making it a dangerous mimic of GCT. * **Hyperparathyroidism (Brown Tumor):** This is the most classic "mimicker" of GCT. Histologically, Brown tumors are virtually indistinguishable from GCTs as they contain abundant giant cells. Clinical correlation with serum calcium and PTH levels is essential. **NEET-PG High-Yield Pearls:** 1. **GCT (Osteoclastoma):** Occurs in the **epiphysis** after skeletal maturity (20-40 years). It shows a "Soap Bubble" appearance on X-ray. 2. **Giant Cell Rich Lesions:** Remember the mnemonic **"G-A-B-O"**: **G**iant Cell Tumor, **A**neurysmal Bone Cyst, **B**rown Tumor (Hyperparathyroidism), and **O**steoblastoma/Osteosarcoma (Telangiectatic). 3. **Location:** While GCT is common in the distal femur/proximal tibia, when a "GCT-like" lesion appears in the **small bones of hands/feet**, always rule out an ABC or a Brown Tumor first.

Q: Which of the following is considered a precancerous lesion of bone?

All of the above. **Explanation:** A **precancerous (premalignant) lesion** of the bone is a benign condition or a chronic inflammatory state that carries a significantly higher risk of transforming into a malignancy, most commonly Osteosarcoma or Squamous Cell Carcinoma. * **Paget Disease (Osteitis Deformans):** In elderly patients, Paget disease is a well-known precursor to **Pagetoid Osteosarcoma**. The rapid bone turnover and hypervascularity increase the risk of malignant transformation (seen in ~1% of cases). * **Chronic Osteomyelitis:** Long-standing infection with a persistent discharging sinus can lead to malignant transformation of the skin/tract epithelium into **Squamous Cell Carcinoma** (Marjolin’s ulcer). Rarely, it can also lead to Osteosarcoma or Fibrosarcoma. * **Benign Giant Cell Tumor (GCT):** While primarily benign, GCT is "locally aggressive." It can undergo malignant transformation (Secondary Malignant GCT), especially following radiotherapy, or rarely, it can metastasize to the lungs even in its benign histological form. **High-Yield Clinical Pearls for NEET-PG:** * **Most common malignancy in Paget disease:** Osteosarcoma. * **Marjolin’s Ulcer:** A squamous cell carcinoma arising in a chronic burn scar or a chronic osteomyelitis sinus tract. * **Other Precancerous Lesions:** Enchondroma (especially in Ollier disease/Maffucci syndrome), Osteochondroma (especially in Multiple Exostoses), and Fibrous Dysplasia (McCune-Albright syndrome). * **Radiation:** Previous exposure to therapeutic radiation is a major risk factor for secondary bone sarcomas.

Q: What is the radiological hallmark of Osteosarcoma?

Sun ray appearance. ### Explanation **Correct Option: B. Sun ray appearance** Osteosarcoma is a highly aggressive malignant bone tumor characterized by rapid growth. As the tumor expands, it lifts the periosteum away from the bone cortex. The malignant cells stimulate the formation of new bone along the stretched perforating fibers (Sharpey’s fibers) perpendicular to the bone surface. This creates a radiating, spiculated pattern of calcification known as the **"Sun ray" or "Sunburst" appearance**. **Analysis of Incorrect Options:** * **A. Soap bubble appearance:** This is the hallmark of **Giant Cell Tumor (Osteoclastoma)**, typically seen in the epiphysis of long bones. It can also be seen in Adamantinoma. * **C. Osteoid formation by neoplastic cells:** While this is the **pathological/histological hallmark** of Osteosarcoma, the question specifically asks for the **radiological** hallmark. * **D. Cotton wool appearance:** This is characteristic of **Paget’s disease of the bone** (specifically in the skull), representing thickened, disorganized sclerotic patches. **NEET-PG High-Yield Pearls:** 1. **Codman’s Triangle:** Another classic radiological sign of Osteosarcoma, formed when the tumor elevates the periosteum, creating a triangular area of new subperiosteal bone at the tumor margin. 2. **Location:** Most common site is the **metaphysis** of long bones, particularly around the knee (distal femur/proximal tibia). 3. **Age Group:** It shows a bimodal distribution, primarily affecting adolescents (10–20 years) and elderly patients with pre-existing Paget’s disease. 4. **Metastasis:** The most common site of distant spread is the **lungs** (via hematogenous route).

Question 1

What is the characteristic location of Ewing's sarcoma?

Accepted Answer

Diaphysis

Answer

Epiphysis

Answer

Metaphysis

Answer

Any of the above

Question 2

Osteosarcoma originates from which type of cells?

Accepted Answer

Osteoblasts

Answer

Osteocytes

Answer

Chondrocytes

Answer

Osteoclasts

Question 3

What is the most common primary malignant bone tumor?

Accepted Answer

Multiple myeloma

Answer

Osteosarcoma

Answer

Osteochondroma

Answer

Osteoclastoma

Question 4

What is the most common type of patellar bursitis?

Accepted Answer

Prepatellar bursitis

Answer

Suprapatellar bursitis

Answer

Infrapatellar bursitis

Answer

Pes anserine bursitis

Question 5

The differential diagnosis of a lesion, histologically resembling a giant cell tumor in the small bones of the hands or feet, includes all of the following except:

Accepted Answer

Fibrosarcoma

Answer

Aneurysmal bone cyst

Answer

Osteosarcoma

Answer

Hyperparathyroidism

Question 6

A 15-year-old boy reports with a rapidly growing swelling of the mandible with intermittent pain. Radiographs reveal formation of new subperiosteal bone producing an 'onion skin' appearance. The patient also has lip paresthesia and an elevated white blood cell count. Which of the following statements is true for Ewing's sarcoma?

Accepted Answer

An episode of trauma often precedes the development of Ewing's sarcoma.

Answer

Trauma is the main etiology in the development of Ewing's sarcoma.

Answer

A relationship between trauma and Ewing's sarcoma has never been reported.

Answer

Trauma can be considered as an etiology for Ewing's sarcoma provided there is secondary infection.

Question 7

Which of the following is considered a precancerous lesion of bone?

Accepted Answer

All of the above

Answer

Paget disease

Answer

Chronic osteomyelitis

Answer

Benign giant cell tumor

Question 8

Which of the following is not associated with multiple myeloma?

Accepted Answer

Carpopedal spasm

Answer

Bone pain

Answer

Metastatic calcification

Answer

Punched out lesion in the skull

Question 9

Which of the following bone tumors arise from the diaphysis?

Accepted Answer

Osteoid osteoma

Answer

Chondrosarcoma

Answer

Ewing's tumor

Answer

Osteoclastoma

Question 10

What is the radiological hallmark of Osteosarcoma?

Accepted Answer

Sun ray appearance

Answer

Soap bubble appearance

Answer

Osteoid formation by neoplastic cells

Answer

Cotton wool appearance

Bone Tumors — MCQs

Bone Tumors — MCQs

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