Bone Tumors — MCQs

A 15-year-old boy presented with painful swelling over the left shoulder. Radiograph of the shoulder showed an osteolytic area with stippled calcification over the proximal humeral epiphysis. Biopsy of the lesion revealed an immature fibrous matrix with scattered giant cells. What is the most likely diagnosis?

Bone Tumors Indian Medical PG Practice Questions and MCQs

Question 101: All of the following are true about Ewing's sarcoma except:

A. Low grade tumors have a good prognosis. (Correct Answer)
B. Pain is the most common symptom.
C. Onion peel appearance on imaging.
D. Associated with t(11;22) translocation.

Explanation: **Explanation:** Ewing’s sarcoma is a highly aggressive, small round blue cell tumor. The correct answer is **Option A** because the statement is factually incorrect: **Ewing’s sarcoma is always considered a high-grade malignancy.** There is no "low-grade" variant of this tumor. All cases are treated with an intensive multimodal approach (chemotherapy, surgery, and/or radiotherapy) because of its high potential for early metastasis. **Analysis of other options:** * **Option B (Pain):** Pain is indeed the most common presenting symptom, often accompanied by local swelling. It may mimic osteomyelitis due to associated systemic features like fever and elevated ESR. * **Option C (Onion peel appearance):** This is the classic radiological hallmark. It represents a **lamellated periosteal reaction** caused by the tumor pushing the periosteum away from the bone in successive layers. * **Option D (t(11;22) translocation):** This is the characteristic genetic marker found in approximately 85-90% of cases. It results in the fusion of the *EWS* gene on chromosome 22 to the *FLI1* gene on chromosome 11. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Derived from neuroectodermal cells (PAS positive due to cytoplasmic glycogen). * **Location:** Most commonly affects the **diaphysis** (shaft) of long bones (Femur > Tibia > Humerus). * **Age Group:** Typically occurs in the first and second decades of life (5–20 years). * **Histo-pathology:** Characterized by **Homer-Wright rosettes**. * **Prognosis:** The most important prognostic factor is the presence of metastasis at the time of diagnosis (Lung is the most common site of metastasis).

Question 102: A 15-year-old school-going student complains of moderate occasional pain and swelling over the right knee joint. An X-ray shows a lesion in the right distal femoral epiphysis. What is the likely diagnosis?

A. Enchondroma
B. Osteochondroma
C. Osteoclastoma
D. Chondroblastoma (Correct Answer)

Explanation: **Explanation:** The diagnosis of bone tumors in NEET-PG often hinges on three key factors: **Age, Location, and Radiographic appearance.** **Why Chondroblastoma is correct:** Chondroblastoma is a rare, benign bone tumor that characteristically occurs in the **epiphysis** of long bones. It typically affects adolescents (10–20 years), matching the patient’s age (15 years). The distal femur is the most common site. On X-ray, it appears as a well-defined lytic lesion with a thin sclerotic rim, sometimes showing "fluffy" calcifications (Codman’s triangle is rare here, but "chicken-wire" calcification is a classic histological finding). **Why other options are incorrect:** * **Enchondroma:** These are most commonly found in the **small bones of the hands and feet** (metaphysis/diaphysis). While they are cartilaginous, they do not typically present in the epiphysis of the femur in a teenager. * **Osteochondroma:** This is the most common benign bone tumor. It presents as a bony outgrowth (exostosis) away from the joint, usually at the **metaphysis**, not as an intra-epiphyseal lesion. * **Osteoclastoma (Giant Cell Tumor):** While GCT is also epiphyseal (or rather, subchondral/metaphyseal-epiphyseal), it typically occurs in **skeletally mature** individuals (20–40 years) after the growth plate has closed. A 15-year-old is more likely to have a Chondroblastoma. **High-Yield Clinical Pearls for NEET-PG:** * **Epiphyseal Tumors:** Remember the mnemonic **"CEO"** (Chondroblastoma, Enchondroma—rarely, Osteoclastoma). * **Chondroblastoma Histology:** Look for "Chicken-wire calcification" and "Cobblestone appearance." * **GCT (Osteoclastoma):** Look for "Soap-bubble appearance" on X-ray and "Double bubble sign." * **Osteoid Osteoma:** Pain relieved by Aspirin/NSAIDs; shows a central "nidus."

Question 103: What condition is characterized by the presence of a nidus?

A. Osteoid osteoma (Correct Answer)
B. Osteosarcoma
C. Ewing's sarcoma
D. Chondroblastoma

Explanation: **Explanation:** **Osteoid Osteoma** is the correct answer because the **nidus** is its pathognomonic radiological and histological feature. A nidus is a small, well-demarcated core of osteoid tissue (usually <1.5–2 cm) surrounded by a zone of reactive sclerotic bone. It produces high levels of prostaglandins, which explains the classic clinical presentation of severe nocturnal pain that is characteristically relieved by Aspirin or NSAIDs. **Why the other options are incorrect:** * **Osteosarcoma:** Characterized by the production of malignant osteoid by spindle cells. Key radiological features include the "Sunburst appearance" and "Codman’s triangle." * **Ewing's Sarcoma:** A small round blue cell tumor characterized by an "Onion-skin" periosteal reaction and the t(11;22) translocation. * **Chondroblastoma:** An epiphyseal tumor in young patients. Its hallmark histological feature is the "Chicken-wire" pattern of calcification, not a nidus. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Most common in the femur and tibia (cortex of long bones). * **Imaging:** CT scan is the investigation of choice to visualize the nidus. On MRI, the extensive perifocal edema can sometimes lead to a misdiagnosis of a more aggressive lesion. * **Treatment:** Medical management with NSAIDs is the first line; if refractory, **Radiofrequency Ablation (RFA)** is the gold standard treatment. * **Note:** If the nidus is >2 cm, the diagnosis shifts to **Osteoblastoma**, which typically involves the posterior elements of the spine and is not relieved by aspirin.

Question 104: An X-ray of the tibia shows a bony growth. Biopsy confirms the tumor to be benign. Which is the commonest true benign bone tumor?

A. Bony cyst
B. Chondroma
C. Chordoma
D. Osteoid osteoma (Correct Answer)

Explanation: **Explanation:** **Osteoid Osteoma** is considered the most common **true benign bone tumor**. In orthopaedic oncology, a "true" tumor refers to a neoplastic proliferation of cells, as opposed to developmental anomalies or reactive lesions. Osteoid osteoma is a small, bone-forming tumor characterized by a central "nidus" (less than 2 cm) surrounded by reactive sclerosis. It classically presents with nocturnal pain that is dramatically relieved by Aspirin or NSAIDs due to high prostaglandin levels within the nidus. **Analysis of Incorrect Options:** * **Bony Cyst (e.g., Simple Bone Cyst):** These are classified as **tumor-like lesions** or developmental abnormalities rather than true neoplasms. * **Chondroma (Enchondroma):** While common, especially in the small bones of the hands and feet, it is less frequent than Osteoid Osteoma in general population surveys. * **Chordoma:** This is a **malignant** (though slow-growing) tumor arising from remnants of the primitive notochord. It is most commonly found in the sacrum and clivus. **NEET-PG High-Yield Pearls:** * **Most common benign bone lesion:** Osteochondroma (Note: Many textbooks classify this as a developmental growth plate anomaly rather than a "true" neoplasm). * **Most common true benign bone tumor:** Osteoid Osteoma. * **Radiological Hallmark:** A radiolucent **nidus** surrounded by dense perifocal bone sclerosis. * **Treatment of Choice:** Radiofrequency ablation (RFA) is now the gold standard, replacing surgical excision.

Question 105: In which part of the bone is a giant cell tumor typically seen?

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

Explanation: ### Explanation **Giant Cell Tumor (GCT)**, also known as **Osteoclastoma**, is a benign but locally aggressive tumor. The hallmark of GCT is its specific anatomical location: it is a **subarticular tumor** that typically arises in the **Epiphysis** after the closure of the growth plate. #### Why Epiphysis is Correct: GCT originates in the epiphysis and often extends into the adjacent metaphysis. It is characterized by the proliferation of mononuclear stromal cells and numerous multinucleated giant cells. On X-ray, it typically presents as an eccentric, "soap-bubble" appearance that extends right up to the subchondral bone (articular surface). #### Why Other Options are Incorrect: * **Metaphysis:** This is the most common site for most primary bone tumors, such as **Osteosarcoma** and **Osteochondroma**. While GCT can involve the metaphysis, its point of origin is the epiphysis. * **Diaphysis:** This is the shaft of the bone. Common tumors here include **Ewing’s Sarcoma**, Osteoid Osteoma, and Adamantinoma. * **Growth Plate:** This is a cartilaginous zone in children. GCT typically occurs in young adults (20–40 years) **after** the growth plate has fused. #### NEET-PG High-Yield Pearls: * **Age Group:** 20–40 years (Skeletal maturity is a prerequisite). * **Common Sites:** Lower end of Radius (most common), Lower end of Femur, and Upper end of Tibia. * **Radiology:** Eccentric, lytic lesion with a **"Soap-bubble appearance."** * **Pathology:** "Double-contour" nuclei in stromal cells; giant cells contain 50–100 nuclei. * **Treatment:** Extensive curettage followed by packing with bone graft or bone cement (Phenol/Liquid Nitrogen used as adjuvants). * **Grading:** Campanacci Staging is used for GCT.

Question 106: A 20-year-old patient presents with a sclerotic lesion at the diaphysis. What is the most likely diagnosis?

A. Osteosarcoma
B. Ewing's sarcoma
C. Osteoid osteoma (Correct Answer)
D. Osteochondroma

Explanation: ### Explanation **Correct Answer: C. Osteoid Osteoma** The diagnosis of **Osteoid Osteoma** is based on the patient's age and the characteristic radiological appearance. It typically affects adolescents and young adults (10–25 years). Radiologically, it presents as a small radiolucent **nidus** (less than 2 cm) surrounded by a significant zone of reactive **perifocal sclerosis**. While it can occur in the metaphysis, it is one of the classic tumors found in the **diaphysis** of long bones (especially the femur and tibia). **Why other options are incorrect:** * **Osteosarcoma:** Typically occurs in the **metaphysis** (the site of maximum growth). While it can show sclerosis, it usually presents with a "sunburst" periosteal reaction and Codman’s triangle, rather than a localized sclerotic diaphyseal lesion. * **Ewing’s Sarcoma:** Although it is a **diaphyseal** tumor in young patients, it is characterized by an aggressive "onion-skin" periosteal reaction and a large soft tissue component, rather than a purely sclerotic lesion. * **Osteochondroma:** This is a benign outgrowth (exostosis) usually found at the **metaphysis**. It grows away from the joint and is characterized by a cartilage cap, not a sclerotic diaphyseal lesion. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Symptom:** Severe nocturnal pain that is characteristically **relieved by NSAIDs/Aspirin** (due to high prostaglandin levels in the nidus). * **Common Sites:** Proximal femur (most common), followed by the tibia and spine (posterior elements). * **Radiology:** If the nidus is >2 cm, the diagnosis shifts to **Osteoblastoma**. * **Treatment:** Medical management with NSAIDs; if refractory, Radiofrequency Ablation (RFA) is the gold standard.

Question 107: Mazabraud syndrome is characterized by which of the following?

A. Fibrous dysplasia with intramuscular myxomas (Correct Answer)
B. Fibrous dysplasia with skeletal changes and cutaneous pigmentation
C. Fibrous dysplasia with craniofacial, rib, and skin deformities
D. Fibrous dysplasia with precocious puberty and hyperparathyroidism

Explanation: **Mazabraud syndrome** is a rare genetic disorder characterized by the association of **Fibrous Dysplasia (FD)** and **Intramuscular Myxomas**. ### **Explanation of the Correct Answer** The hallmark of Mazabraud syndrome is the coexistence of polyostotic fibrous dysplasia (where normal bone is replaced by fibrous tissue and haphazardly arranged trabeculae) and multiple soft tissue myxomas. These myxomas are benign mesenchymal tumors typically found in the skeletal muscles adjacent to the affected bones. Both conditions are caused by post-zygotic mutations in the **GNAS1 gene**, which leads to overactivity of the G-protein signaling pathway. ### **Analysis of Incorrect Options** * **Option B:** This describes **McCune-Albright Syndrome**, which consists of a triad of Polyostotic Fibrous Dysplasia, Café-au-lait spots (Coast of Maine appearance), and hyperfunctioning endocrinopathies. * **Option C:** This describes general clinical features of **Polyostotic Fibrous Dysplasia** without the specific syndromic association of soft tissue tumors. * **Option D:** This is a variation of **McCune-Albright Syndrome**. While precocious puberty is common, the associated endocrinopathy is more frequently hyperthyroidism or GH excess rather than hyperparathyroidism. ### **High-Yield Clinical Pearls for NEET-PG** * **Genetic Mutation:** Both Mazabraud and McCune-Albright syndromes involve the **GNAS1 gene** mutation. * **Radiology:** Fibrous dysplasia shows a characteristic **"Ground Glass Appearance"** on X-ray. * **Histology:** Look for **"Chinese Letter Patterns"** (irregular bony trabeculae without osteoblastic rimming). * **Malignant Transformation:** Patients with Mazabraud syndrome have a slightly higher risk of the fibrous dysplasia transforming into **Osteosarcoma** compared to isolated FD.

Question 108: What is the most common malignant bone tumor?

A. Osteogenic sarcoma
B. Metastatic tumors (Secondaries) (Correct Answer)
C. Osteoma
D. Enchondroma

Explanation: **Explanation:** The correct answer is **Metastatic tumors (Secondaries)**. In clinical practice, metastatic bone disease is significantly more common than any primary bone malignancy. While Osteosarcoma is the most common *primary* malignant bone tumor, it is far outnumbered by secondary deposits from primary cancers elsewhere in the body (most commonly from the prostate, breast, lung, kidney, and thyroid). **Analysis of Options:** * **A. Osteogenic sarcoma:** This is the most common **primary** malignant bone tumor in children and adolescents. However, when considering all bone malignancies (primary + secondary), it ranks lower than metastatic disease. * **C. Osteoma:** This is a **benign** bone tumor, most commonly found in the skull and facial bones (often associated with Gardner’s syndrome). * **D. Enchondroma:** This is the most common **benign** tumor of the small bones of the hands and feet. It is not a malignant condition. **High-Yield Clinical Pearls for NEET-PG:** * **Most common bone tumor overall:** Metastatic tumors. * **Most common primary malignant bone tumor:** Osteosarcoma (if Multiple Myeloma is excluded) or Multiple Myeloma (if considered a bone tumor). * **Most common site for bone metastasis:** The spine (specifically the thoracic spine). * **Commonest source of bone metastasis:** In males, it is Prostate cancer; in females, it is Breast cancer. * **Radiological appearance:** Most metastases are osteolytic (e.g., Kidney, Thyroid), but Prostate cancer typically produces osteoblastic (sclerotic) lesions.

Question 109: What is the most common site of eosinophilic granuloma?

A. Radius
B. Femur
C. Skull (Correct Answer)
D. Lumbar vertebrae

Explanation: **Explanation:** **Eosinophilic Granuloma (EG)** is the most common and benign form of **Langerhans Cell Histiocytosis (LCH)**. It typically presents as a solitary, osteolytic lesion in children and young adults (peak age 5–10 years). **Why Skull is the Correct Answer:** The **skull** is statistically the most frequent site of involvement for eosinophilic granuloma (accounting for approximately 50% of cases). Within the skull, the calvarium (frontal and parietal bones) is most commonly affected. Radiographically, it presents as a characteristic **"punched-out" lesion** with beveled edges (due to unequal destruction of the inner and outer tables of the skull). **Analysis of Incorrect Options:** * **Radius:** Long bones of the upper limb are relatively uncommon sites for EG compared to the axial skeleton. * **Femur:** While the femur is the most common **long bone** affected by EG, it ranks second overall behind the skull. In long bones, the lesion is typically located in the diaphysis or metaphysis. * **Lumbar Vertebrae:** The spine is a known site, but it is less common than the skull. When EG affects the spine, it often leads to symmetrical collapse of the vertebral body, a classic sign known as **Vertebra Plana (Calvé disease)**. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad (Hand-Schüller-Christian disease):** Exophthalmos, Diabetes Insipidus, and Bone lesions (Skull). * **Radiology:** "Punched-out" appearance in the skull and "Vertebra Plana" in the spine. * **Pathology:** Presence of **Birbeck granules** (tennis-racket shaped) on electron microscopy and **CD1a/S100** positivity on immunohistochemistry. * **Treatment:** Often self-limiting; symptomatic lesions may require curettage or low-dose steroids.

Question 110: A 15-year-old boy presented with painful swelling over the left shoulder. Radiograph of the shoulder showed an osteolytic area with stippled calcification over the proximal humeral epiphysis. Biopsy of the lesion revealed an immature fibrous matrix with scattered giant cells. What is the most likely diagnosis?

A. Giant cell tumor
B. Chondroblastoma (Correct Answer)
C. Osteosarcoma
D. Chondromyxoid fibroma

Explanation: **Explanation:** The diagnosis is **Chondroblastoma** based on the classic triad of age, location, and radiographic appearance. 1. **Why Chondroblastoma is correct:** * **Age:** It typically occurs in the second decade of life (10–20 years). * **Location:** It is one of the few tumors that is characteristically **epiphyseal** in origin. The proximal humerus is the second most common site after the distal femur. * **Radiology:** It appears as a well-defined osteolytic lesion with **stippled calcification** (fleck-like), representing the "chicken-wire" calcification seen histologically. * **Pathology:** Biopsy showing an immature matrix with scattered giant cells and "cobblestone" chondroblasts is pathognomonic. 2. **Why other options are incorrect:** * **Giant Cell Tumor (GCT):** While also epiphyseal, GCT typically occurs in skeletally mature individuals (**20–40 years**) after the growth plate has closed. It lacks stippled calcification. * **Osteosarcoma:** Usually involves the **metaphysis** and presents with aggressive features like Sunray spicule appearance or Codman’s triangle, rather than a well-defined epiphyseal lytic lesion. * **Chondromyxoid Fibroma:** This is a rare tumor that typically involves the **metaphysis** (eccentrically located) and lacks the specific epiphyseal predilection of chondroblastoma. **NEET-PG High-Yield Pearls:** * **Epiphyseal Tumors Mnemonic:** "**C**lear **G**iant **C**hondroblastoma" (**C**lear cell chondrosarcoma, **G**iant cell tumor, **C**hondroblastoma). * **Codman’s Tumor:** Another name for Chondroblastoma. * **Histology Hallmark:** "Chicken-wire" calcification (calcification surrounding individual chondroblasts). * **Treatment:** Curettage and bone grafting.

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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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Bone Tumors — MCQs

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