Bone Tumors Practice Questions

Q: An eight-year-old boy presents with back pain and mild fever. His plain X-ray of the dorsolumbar spine reveals a solitary collapsed dorsal vertebra with preserved disc spaces. There was no associated soft tissue shadow. What is the most likely diagnosis?

Histiocytosis. ### Explanation The clinical presentation of a solitary collapsed vertebra with preserved disc spaces in a child is a classic description of **Vertebra Plana** (Calvé’s disease). **1. Why Histiocytosis is Correct:** Langerhans Cell Histiocytosis (LCH), specifically Eosinophilic Granuloma, is the most common cause of **Vertebra Plana** in children. The pathology involves a localized histiocytic infiltration that leads to rapid bone destruction and symmetrical collapse of the vertebral body. Key diagnostic features present in this case include: * **Preserved disc spaces:** Unlike infections, LCH does not cross the disc. * **Solitary lesion:** Often affects a single vertebral body. * **Age:** Most common in children aged 5–10 years. **2. Why Other Options are Incorrect:** * **Tuberculosis (Pott’s Spine):** This is the most common cause of spinal collapse in India, but it typically **destroys the disc space** (paradiscal type) and is almost always associated with a **pre/paravertebral soft tissue shadow** (cold abscess). * **Ewing’s Sarcoma:** While it can cause vertebral collapse, it usually presents with a significant soft tissue mass and more systemic constitutional symptoms. * **Metastasis:** Rare in an 8-year-old. Neuroblastoma is the most common pediatric metastatic bone tumor, but it usually involves multiple levels and shows pedicle destruction. **3. NEET-PG High-Yield Pearls:** * **Vertebra Plana (Coin-on-edge appearance):** Pathognomonic for LCH in children. * **Differential for Vertebra Plana:** Remember the mnemonic **"CHEST"** (C-Calvé’s/LCH, H-Hemangioma, E-Ewing’s, S-Staph infection, T-Tuberculosis/Tumor). * **Radiological Hallmark:** The vertebral body is flattened into a thin disc, but the height of the adjacent intervertebral discs remains normal. * **Prognosis:** Excellent; the vertebral height often partially reconstitutes over time with conservative management.

Q: The X-ray of a knee in an adolescent boy is shown. What is the probable diagnosis?

Chondromyxoid fibroma. ***Chondromyxoid fibroma*** - Presents as an **eccentric metaphyseal lytic lesion** at the **proximal tibia** with **sclerotic margins** and **no calcification**, classic for this rare benign tumor in adolescents. - Typically affects the **metaphysis** of long bones, particularly around the knee, and shows a **well-defined cortical margin** without aggressive features. *Osteosarcoma* - Would demonstrate **aggressive periosteal reaction** with **Codman's triangle** or **sunburst pattern**, not seen in this case. - Commonly shows **osteoid matrix calcification** and **cortical destruction** with soft tissue extension, contrasting with the well-demarcated lesion shown. *Bone cyst with fracture* - Typically presents as a **central metaphyseal lesion** rather than eccentric, often with the **fallen fragment sign** after pathological fracture. - Shows **fluid-fluid levels** on MRI and lacks the **sclerotic rim** characteristic of chondromyxoid fibroma. *Osteitis fibrosa cystica* - Represents **brown tumors** associated with **hyperparathyroidism**, typically affecting multiple bones simultaneously. - Would present with elevated **serum calcium** and **parathyroid hormone levels**, along with **generalized bone demineralization** rather than an isolated lesion.

Q: What is the typical time period between the occurrence of osteosarcoma following radiation therapy?

10 years. **Explanation:** **Radiation-induced Osteosarcoma (RIS)** is a well-recognized late complication of radiotherapy. The correct answer is **10 years** because post-radiation sarcomas are characterized by a long latency period. 1. **Why 10 years is correct:** For a bone tumor to be classified as radiation-induced, it must meet the **Cahan’s Criteria**. One of the primary requirements is a significant latent period between irradiation and the development of the sarcoma. While the minimum threshold is often cited as 3–5 years, the **average (median) latency period is approximately 10 years**. This time is required for the accumulation of radiation-induced genetic mutations and malignant transformation of the bone cells. 2. **Why other options are incorrect:** * **1 Year (A):** This is too short. A tumor appearing within a year is likely a recurrence of the primary malignancy or a metastasis, rather than a new radiation-induced primary. * **3 & 5 Years (B & C):** While 3–5 years is considered the minimum "threshold" for diagnosis, it does not represent the "typical" or peak time of occurrence. NEET-PG questions usually seek the median or most common presentation period, which is a decade. **High-Yield Clinical Pearls for NEET-PG:** * **Cahan’s Criteria for RIS:** 1) Tumor must arise in the field of radiation; 2) Histology must be different from the primary tumor; 3) A long latent period (usually >5 years) must have elapsed. * **Most Common Type:** Osteosarcoma is the most common histological subtype of radiation-induced bone sarcoma. * **Prognosis:** Radiation-induced osteosarcomas generally have a **worse prognosis** than primary (de novo) osteosarcomas due to their central location and the difficulty of surgical resection in previously irradiated, fibrotic tissue. * **Common Sites:** Often seen following treatment for breast cancer (ribs/scapula) or retinoblastoma.

Q: What is the most common tumor of the vertebral spine in adults?

Secondary deposits. **Explanation:** The most common tumor of the vertebral spine in adults is **Secondary deposits (Metastatic disease)**. The spine is the most frequent site for skeletal metastasis due to its high content of red marrow and the presence of **Batson’s plexus** (a valveless venous network that allows retrograde spread of tumor cells from the pelvis, abdomen, and thorax). **Analysis of Options:** * **A. Secondary deposits (Correct):** Metastases outnumber primary bone tumors by a ratio of roughly 40:1. In adults, the most common primary sources are cancers of the **Prostate, Breast, Lung, and Kidney**. * **B. Multiple myeloma:** This is the most common **primary malignant** bone tumor in adults. While it frequently involves the spine, it is statistically less common than metastatic disease from non-marrow primaries. * **C. Lymphoma:** While it can involve the vertebrae (often presenting as an "Ivory vertebra"), it is significantly less common than metastases or myeloma. * **D. Hemangioma:** This is the most common **benign** tumor of the vertebral column. It is often an incidental finding on imaging, characterized by a "corduroy cloth" or "honeycomb" appearance. **NEET-PG High-Yield Pearls:** * **Most common site of spinal metastasis:** Thoracic spine (followed by lumbar). * **Earliest sign on X-ray:** Loss of the **pedicle** (the "Winking Owl" sign), as the pedicle lacks a cortex and is easily destroyed. * **Investigation of choice:** **MRI** is the most sensitive for early detection; **PET-CT** is used for staging. * **Osteoblastic vs. Osteolytic:** Prostate cancer typically causes osteoblastic (sclerotic) lesions, while Lung and Breast cancers often cause osteolytic lesions.

Q: Which of the following conditions is characterized by a "moth-eaten" bone appearance?

Multiple myeloma. **Explanation:** The **"moth-eaten"** pattern of bone destruction refers to a type of aggressive osteolysis characterized by multiple small, scattered, and poorly defined lucent areas. This pattern indicates a rapidly progressing lesion where the bone does not have sufficient time to mount a sclerotic defensive response. **Why Multiple Myeloma is correct:** Multiple Myeloma is a plasma cell dyscrasia that causes diffuse bone marrow infiltration. The malignant plasma cells secrete osteoclast-activating factors (like RANKL), leading to rapid bone resorption. Radiographically, this manifests as classic **"punched-out"** lesions or a diffuse **"moth-eaten"** appearance, particularly in the skull, spine, and pelvis. **Analysis of Incorrect Options:** * **A. Osteoid Osteoma:** Characterized by a small radiolucent **nidus** (less than 2 cm) surrounded by a dense zone of reactive sclerosis. It typically presents with nocturnal pain relieved by NSAIDs. * **C. Eosinophilic Granuloma:** Part of Langerhans Cell Histiocytosis (LCH). While it can cause bone destruction, it is classically associated with a **"punched-out"** appearance in the skull (without sclerosis) or a **"beveled edge"** appearance. * **D. Chondromyxoid Fibroma:** A rare benign cartilaginous tumor that typically presents as an eccentric, **soap-bubble**, or lobulated lucent lesion with a well-defined sclerotic rim, usually in the metaphysis. **NEET-PG High-Yield Pearls:** * **Moth-eaten/Permeative patterns** are seen in: Multiple Myeloma, Ewing’s Sarcoma, Osteosarcoma, and Metastatic neuroblastoma. * **Geographic destruction** (well-defined) suggests benign/slow-growing lesions (e.g., GCT). * **Multiple Myeloma** is the most common primary bone malignancy in adults. * **Key Lab Finding:** Bence-Jones proteins in urine and a "reversed" A:G ratio. Note that a **Bone Scan** is often negative in Multiple Myeloma because there is no osteoblastic activity.

Q: An X-ray of the proximal femur in a patient presenting with hip pain shows a specific deformity. What is this deformity?

Shepherd crook deformity. ***Shepherd crook deformity*** - Classic **coxa vara** deformity of the proximal femur seen in **fibrous dysplasia**, where the femoral neck bends downward resembling a shepherd's crook. - Results from **mechanical stress** on weakened bone filled with fibrous tissue, causing progressive **varus angulation** of the femoral neck. *Blade of grass deformity* - Characteristic radiological appearance of the **tibia** in **Paget's disease**, showing widened cortex and trabecular pattern. - Involves **long bones** like tibia and fibula, not typically the proximal femur as described in this case. *Chicken wire appearance* - Pathognomonic feature of **vertebral hemangiomas** showing coarse vertical trabeculae on lateral radiographs. - Specifically affects **vertebral bodies**, not the proximal femur or hip region. *Corduroy appearance* - Another radiological sign of **vertebral hemangiomas** seen on **frontal radiographs** showing vertical striations. - Limited to **spinal vertebrae** and does not involve the femoral neck or hip joint area.

Q: Which of the following is NOT a common site of primary bone metastasis?

Brain. **Explanation:** The correct answer is **Brain**. Primary bone metastasis refers to cancers that frequently spread to the skeletal system. The brain is not a common primary source for bone metastasis; in fact, primary brain tumors (like Gliomas) rarely metastasize outside the central nervous system because they lack a lymphatic drainage system and patients often succumb to the local effects of the tumor before systemic spread occurs. **Analysis of Options:** * **Breast (Option A):** This is the most common primary site for bone metastasis in **females**. These lesions are typically **mixed** (osteolytic and osteoblastic). * **Prostate (Option B):** This is the most common primary site in **males**. It is classically associated with **osteoblastic** (sclerotic) lesions due to the secretion of prostate-specific acid phosphatase. * **Kidney (Option D):** Renal Cell Carcinoma (RCC) frequently spreads to the bone, typically causing highly vascular, **purely osteolytic** lesions. **NEET-PG High-Yield Pearls:** * **Mnemonic for Bone Metastasis:** "**B**e **P**olite **L**ove **K**ids **T**erribly" (**B**reast, **P**rostate, **L**ung, **K**idney, **T**hyroid). * **Most common site of bone metastasis:** The **spine** (specifically the thoracic spine) via the **Batson venous plexus**. * **Lesion Types:** * **Osteoblastic:** Prostate (most common), Carcinoid, Small cell lung cancer. * **Osteolytic:** Kidney, Thyroid, Lung (NSCLC). * **Mixed:** Breast. * **Investigation of Choice:** **99mTc-MDP Bone Scan** is the most sensitive screening tool (except for Multiple Myeloma and purely lytic lesions where X-rays or MRI are preferred).

Q: All of the following statements regarding Ewing's sarcoma are true EXCEPT?

Flexner-Wintersteiner rosettes are seen.. ### Explanation **Ewing’s Sarcoma** is a highly malignant, small round blue cell tumor typically affecting children and adolescents. #### Why Option D is the Correct Answer (The "Except" Statement) **Flexner-Wintersteiner rosettes** are characteristic of **Retinoblastoma** (and occasionally Pineoblastoma). In Ewing’s sarcoma, the classic histological finding is **Homer-Wright rosettes**, where tumor cells are arranged around a central fibrillar area. Both are "small round blue cell tumors," but the type of rosette is a critical distinguishing factor for exams. #### Analysis of Incorrect Options (True Statements) * **A. Common location is the diaphysis:** Unlike Osteosarcoma (metaphysis), Ewing’s sarcoma is the most common primary bone tumor to arise in the **diaphysis** (shaft) of long bones (femur, tibia) and flat bones (pelvis). * **B. Symptoms resemble osteomyelitis:** Patients often present with systemic symptoms like fever, elevated ESR, leukocytosis, and a painful, warm swelling. This mimics an infection, making osteomyelitis the primary differential diagnosis. * **C. Translocation t(11;22):** This is the pathognomonic genetic hallmark, found in >90% of cases. It results in the **EWS-FLI1** fusion gene. #### NEET-PG High-Yield Pearls * **Radiology:** Classic **"onion-skin"** periosteal reaction (due to layers of new bone formation). * **Origin:** Derived from primitive neuroectodermal cells (mesenchymal stem cells). * **PAS Staining:** Tumor cells are **PAS positive** because they contain glycogen (unlike Lymphoma). * **Marker:** **CD99** (MIC2) is a highly sensitive membrane marker for Ewing’s sarcoma. * **Treatment:** It is highly radiosensitive; however, the standard of care is a combination of chemotherapy and surgery (VAC regimen: Vincristine, Adriamycin, Cyclophosphamide).

Q: What is the most probable diagnosis based on the X-ray findings in a 20-year-old female presenting with knee swelling?

Osteosarcoma. ***Osteosarcoma*** - Most common **primary bone malignancy** in young adults (10-25 years), typically affecting the **metaphysis** of long bones around the knee (distal femur, proximal tibia). - Classic X-ray features include **mixed lytic-sclerotic lesions**, **Codman's triangle** (periosteal elevation), and **sunburst pattern** of new bone formation. *Osteoclastoma* - Also known as **giant cell tumor**, typically occurs in patients aged **20-40 years** but has a predilection for the **epiphysis** rather than metaphysis. - X-ray shows **purely lytic lesions** with well-defined margins and **soap bubble appearance**, lacking the aggressive mixed pattern seen in osteosarcoma. *Osteochondroma* - Most common **benign bone tumor**, usually presents as an **asymptomatic bony projection** rather than swelling. - X-ray shows a **pedunculated or sessile bony outgrowth** with **cartilaginous cap**, not the destructive mixed lytic-sclerotic pattern typical of malignant tumors. *None of the above* - Given the patient's age (**20 years**), location (**knee**), and typical X-ray findings described, osteosarcoma fits the classic presentation. - The **demographic profile** and **radiological characteristics** strongly support a specific diagnosis rather than an atypical presentation.

Question 1

An eight-year-old boy presents with back pain and mild fever. His plain X-ray of the dorsolumbar spine reveals a solitary collapsed dorsal vertebra with preserved disc spaces. There was no associated soft tissue shadow. What is the most likely diagnosis?

Accepted Answer

Histiocytosis

Answer

Ewing's sarcoma

Answer

Tuberculosis

Answer

Metastasis

Question 2

An 11-year-old boy presents with pain in his right leg. A radiograph shows a "sunburst" appearance with bone destruction, soft tissue mass, new bone formation, and sclerosis limited to the metaphysis of the lower femur. Select the type of bone lesion with which it is most likely to be associated.

Accepted Answer

Osteosarcoma

Answer

Osteoma

Answer

Osteoid osteoma

Answer

Osteoblastoma

Question 3

The X-ray of a knee in an adolescent boy is shown. What is the probable diagnosis?

Accepted Answer

Chondromyxoid fibroma

Answer

Osteosarcoma

Answer

Bone cyst with fracture

Answer

Osteitis fibrosa cystica

Question 4

What is the typical time period between the occurrence of osteosarcoma following radiation therapy?

Accepted Answer

10 years

Answer

1 year

Answer

3 years

Answer

5 years

Question 5

What is the most common tumor of the vertebral spine in adults?

Accepted Answer

Secondary deposits

Answer

Multiple myeloma

Answer

Lymphoma

Answer

Hemangioma

Question 6

Which of the following conditions is characterized by a "moth-eaten" bone appearance?

Accepted Answer

Multiple myeloma

Answer

Osteoid osteoma

Answer

Eosinophilic granuloma

Answer

Chondromyxoid fibroma

Question 7

An X-ray of the proximal femur in a patient presenting with hip pain shows a specific deformity. What is this deformity?

Accepted Answer

Shepherd crook deformity

Answer

Blade of grass deformity

Answer

Chicken wire appearance

Answer

Corduroy appearance

Question 8

Which of the following is NOT a common site of primary bone metastasis?

Accepted Answer

Brain

Answer

Breast

Answer

Prostate

Answer

Kidney

Question 9

All of the following statements regarding Ewing's sarcoma are true EXCEPT?

Accepted Answer

Flexner-Wintersteiner rosettes are seen.

Answer

Common location is the diaphysis of long bones.

Answer

Symptoms resemble osteomyelitis.

Answer

Translocation t(11;22) is classical.

Question 10

What is the most probable diagnosis based on the X-ray findings in a 20-year-old female presenting with knee swelling?

Accepted Answer

Osteosarcoma

Answer

Osteoclastoma

Answer

Osteochondroma

Answer

None of the above

Bone Tumors — MCQs

Bone Tumors — MCQs

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