Musculoskeletal Radiology — MCQs

An 18-year-old male patient presented with pain and swelling in the lower jaw. Intraoral examination revealed localized gingival bleeding in the right posterior region. On palpation, pulsations can be appreciated. Radiographs also showed lesions on the frontal bone. Which condition is present in this patient?

Q257

Based on the provided MRI images of the knee (A and B), which show a well-defined fluid collection anterior to the patella, what is the most likely diagnosis?

Q258

Based on the provided X-ray image, identify the most likely diagnosis.

Q259

Honda or H sign on STIR MRI is characteristic of which condition?

Q260

Based on the provided X-ray image, identify the type of thyroid malignancy.

Musculoskeletal Radiology Indian Medical PG Practice Questions and MCQs

Question 251: Bone density is best studied by which imaging modality?

A. CT scan
B. DEXA scan (Correct Answer)
C. MRI scan
D. Bone scan

Explanation: **Explanation:** **1. Why DEXA Scan is the Correct Answer:** Dual-Energy X-ray Absorptiometry (DEXA) is the **gold standard** for measuring Bone Mineral Density (BMD). It utilizes two X-ray beams with different energy levels to differentiate between bone and soft tissue. Its clinical superiority stems from its high precision, low radiation dose (1/10th of a chest X-ray), and its ability to provide standardized **T-scores** and **Z-scores**, which are essential for diagnosing Osteoporosis and Osteopenia according to WHO criteria. **2. Why Other Options are Incorrect:** * **CT Scan:** While Quantitative CT (QCT) can measure bone density in 3D, a standard CT scan is not the primary tool due to significantly higher radiation exposure and cost. QCT is usually reserved for research or specific complex cases. * **MRI Scan:** MRI is excellent for visualizing soft tissues, bone marrow edema, and occult fractures, but it cannot accurately quantify mineral density because cortical bone yields a low signal (appears black). * **Bone Scan (Scintigraphy):** This functional imaging modality uses Technetium-99m MDP to detect **osteoblastic activity** (bone turnover). It is used to identify metastases, infections, or stress fractures, not to measure density. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sites for DEXA:** The most common sites measured are the **Lumbar spine (L1-L4)** and the **Proximal Femur (Neck of femur)**. * **T-score:** Compares patient BMD to a young healthy adult (30-year-old). * Normal: > -1.0 * Osteopenia: -1.0 to -2.5 * Osteoporosis: ≤ -2.5 * Severe Osteoporosis: ≤ -2.5 + fragility fracture. * **Z-score:** Compares patient BMD to an age-matched and sex-matched peer. A Z-score < -2.0 suggests secondary causes of bone loss.

Question 252: Trolly tract sign is seen in which of the following conditions?

A. Achondroplasia
B. Psoriatic arthritis
C. Osteopetrosis
D. Ankylosing spondylitis (Correct Answer)

Explanation: **Explanation:** **Ankylosing Spondylitis (AS)** is the correct answer. The **Trolley Track sign** is a classic radiographic feature of advanced AS. It is caused by the ossification of the **supraspinous and interspinous ligaments**, which creates a central vertical radiodense line, combined with the ossification of the **apophyseal (facet) joint capsules**, which create two lateral vertical lines. Together, these three parallel lines resemble trolley tracks on a frontal (AP) X-ray of the spine. **Analysis of Incorrect Options:** * **Achondroplasia:** Characterized by "bullet-shaped" vertebrae, posterior scalloping, and a progressive narrowing of the interpedicular distance in the lumbar spine. * **Psoriatic Arthritis:** Typically shows "pencil-in-cup" deformities in the hands and asymmetrical sacroiliitis, but not the trolley track sign. * **Osteopetrosis:** Known for "Erlenmeyer flask" deformities and the "bone-within-a-bone" appearance (endobone) due to defective osteoclast activity. **High-Yield Clinical Pearls for NEET-PG:** * **Bamboo Spine:** Formed by marginal **syndesmophytes** (ossification of the outer fibers of the annulus fibrosus). * **Dagger Sign:** A single central radiodense line on AP X-ray due to ossification of the supraspinous and interspinous ligaments. * **Shiny Corner Sign (Romanus Lesion):** Early sign of AS representing small erosions at the corners of vertebral bodies. * **Andersson Lesion:** Non-infectious spondylodiscitis seen in AS. * **HLA-B27:** Strongly associated with AS (approx. 90% of cases).

Question 253: Expansile pulsating secondary metastasis is a feature of which of the following?

A. Basal cell carcinoma
B. Renal cell carcinoma (Correct Answer)
C. Osteogenic sarcoma
D. Carcinoma of the prostate

Explanation: **Explanation:** The correct answer is **Renal cell carcinoma (RCC)**. **1. Why Renal Cell Carcinoma is correct:** Expansile, osteolytic, and **pulsating** skeletal metastases are characteristic of highly vascular tumors. RCC is the most common cause of such lesions. The "pulsatile" nature occurs because these metastases are extremely hypervascular; the high blood flow within the lesion transmits the arterial pulse, which can sometimes be felt on clinical palpation or heard as a bruit. On imaging, these appear as "blow-out" lytic lesions. **2. Why the other options are incorrect:** * **Basal Cell Carcinoma (BCC):** BCC is a locally invasive skin cancer that rarely metastasizes to distant organs or bones. * **Osteogenic Sarcoma (Osteosarcoma):** This is a primary bone tumor, not a secondary metastasis. While it is vascular, it typically presents with bone formation (osteoid) and a "sunburst" periosteal reaction rather than expansile pulsatile secondary deposits. * **Carcinoma of the Prostate:** This is the classic cause of **osteoblastic (sclerotic)** metastases. These lesions are dense and radio-opaque, not expansile or pulsatile. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Pulsatile Bone Metastases:** **"R-T-C"** (Renal cell carcinoma, Thyroid carcinoma—specifically follicular variety, and Choriocarcinoma). * **Most common source of bone metastasis in males:** Prostate cancer. * **Most common source of bone metastasis in females:** Breast cancer. * **Most common site for bone metastasis:** Spine (Vertebral column). * **Imaging of choice:** While Bone Scan (Technetium-99m MDP) is used for screening, it may show a **"cold lesion"** in pure lytic tumors like RCC or Multiple Myeloma. MRI is more sensitive for detecting early marrow involvement.

Question 254: What is the characteristic radiographic finding described as a "molten wax appearance"?

A. Achondroplasia
B. Pseudogout
C. Melorheostosis (Correct Answer)
D. Osteopetrosis

Explanation: **Explanation:** **Melorheostosis** is a rare, non-hereditary sclerosing bone dysplasia. The characteristic radiographic finding is **"flowing hyperostosis"** along the cortex of tubular bones, which resembles **molten wax dripping down the side of a candle**. This occurs due to linear thickening of the bony cortex, typically following a sclerotome distribution (the area of bone innervated by a single spinal sensory nerve). **Analysis of Options:** * **A. Achondroplasia:** Characterized by rhizomelic shortening of limbs, "trident hand," and spinal findings like narrowing of the interpedicular distance and "bullet-shaped" vertebrae. * **B. Pseudogout (CPPD):** Radiographically presents as **chondrocalcinosis** (linear calcification of articular cartilage or fibrocartilage), most commonly seen in the knees, wrists (triangular fibrocartilage), and symphysis pubis. * **D. Osteopetrosis:** Known as "Marble Bone Disease," it shows diffuse, symmetric osteosclerosis. Key signs include the **"bone-within-a-bone"** appearance and **"sandwich vertebrae"** (dense endplates). **High-Yield Clinical Pearls for NEET-PG:** * **Melorheostosis** often presents with pain, joint stiffness, or limb deformity. It is frequently associated with overlying skin changes like scleroderma-like thickening. * **Hot Spot on Bone Scan:** Despite being a benign condition, melorheostosis shows increased uptake on Technetium-99m MDP bone scans due to active bone remodeling. * **Distribution:** It is usually **monomelic** (affecting one limb) and asymmetric, distinguishing it from the symmetric involvement seen in Osteopetrosis.

Question 255: A 76-year-old man presents with a lytic lesion in the vertebrae. X-ray of the skull showed multiple punched-out lesions. What is the most likely diagnosis?

A. Metastasis
B. Multiple myeloma (Correct Answer)
C. Osteomalacia
D. Hyperparathyroidism

Explanation: ### Explanation **Correct Answer: B. Multiple Myeloma** Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the neoplastic proliferation of a single clone of plasma cells. The hallmark radiological finding in the skull is multiple, well-defined, "punched-out" lytic lesions. These lesions occur because plasma cells produce osteoclast-activating factors (like RANKL), leading to bone resorption without any associated osteoblastic activity (reactive new bone formation). This lack of osteoblastic response is why MM lesions appear purely lytic and are typically **cold on a Technetium-99m bone scan**. **Analysis of Incorrect Options:** * **A. Metastasis:** While metastases are the most common cause of lytic lesions in the elderly, they usually present with "moth-eaten" or ill-defined borders and often trigger some osteoblastic reaction (sclerotic borders). In the skull, metastases are less likely to present as classic "punched-out" holes compared to MM. * **C. Osteomalacia:** This is characterized by inadequate mineralization of the bone osteoid. Radiological features include generalized osteopenia and **Looser’s zones** (pseudofractures), not focal lytic lesions. * **D. Hyperparathyroidism:** This typically presents with "salt and pepper" skull (granular decalcification) rather than discrete punched-out lesions. Other features include subperiosteal bone resorption (classically in the phalanges) and Brown tumors. **NEET-PG High-Yield Pearls:** * **Raindrop Skull:** Another term for the multiple punched-out lesions seen in MM. * **Bone Scan Paradox:** MM is a classic cause of a **false-negative bone scan**; MRI or low-dose CT (Skeletal Survey) is the preferred imaging modality. * **Vertebral Involvement:** MM often involves the vertebral body but characteristically **spares the pedicles** (unlike metastasis, which often involves the pedicles—the "winking owl" sign). * **Bence-Jones Proteins:** These are light chains found in urine, but they are not detected by standard dipsticks (requires sulfosalicylic acid test).

Question 256: An 18-year-old male patient presented with pain and swelling in the lower jaw. Intraoral examination revealed localized gingival bleeding in the right posterior region. On palpation, pulsations can be appreciated. Radiographs also showed lesions on the frontal bone. Which condition is present in this patient?

A. Vascular malformation (Correct Answer)
B. Cherubism
C. Eosinophilic granuloma
D. Brown tumor

Explanation: **Explanation:** The clinical presentation of an 18-year-old with a jaw swelling associated with **gingival bleeding** and **palpable pulsations** is a classic hallmark of a **Vascular Malformation** (specifically Arteriovenous Malformations or Hemangiomas). The presence of pulsations indicates a high-flow vascular lesion. In the jaw, these lesions can cause tooth mobility and spontaneous bleeding from the gingival sulcus. The involvement of the frontal bone suggests a multi-focal or syndromic presentation (e.g., Gorham-Stout disease or multiple cavernous hemangiomas). **Why other options are incorrect:** * **Cherubism:** Typically presents in early childhood (2–7 years) as bilateral, symmetrical painless jaw swellings. Radiographically, it shows multilocular radiolucencies ("soap-bubble" appearance). It does not present with pulsations or gingival bleeding. * **Eosinophilic Granuloma (Langerhans Cell Histiocytosis):** While it can affect the jaw and frontal bone (punched-out lesions), it typically presents with "floating-in-air" teeth due to alveolar bone loss. It is an inflammatory/neoplastic process, not a vascular one, so pulsations are absent. * **Brown Tumor:** Associated with Hyperparathyroidism. While it can cause jaw lesions, it is characterized by biochemical changes (elevated Calcium and PTH) and lacks the vascular pulsations and spontaneous gingival bleeding seen here. **High-Yield Clinical Pearls for NEET-PG:** * **Pulsatile Jaw Lesion:** Always suspect Central Hemangioma or AVM. * **Aspiration:** Mandatory before any surgical intervention in suspected vascular lesions to avoid life-threatening hemorrhage ("The Great Mimicker"). * **Radiology:** May show a "sunburst" periosteal reaction or "honeycomb" radiolucency. * **Frontal Bone Involvement:** In the context of vascular lesions, consider **Gorham-Stout Disease** (Vanishing Bone Disease), characterized by progressive osteolysis and vascular proliferation.

Question 257: Based on the provided MRI images of the knee (A and B), which show a well-defined fluid collection anterior to the patella, what is the most likely diagnosis?

A. Rheumatoid arthritis
B. Housemaid's knee (Correct Answer)
C. Gout
D. Subdermal abscess

Explanation: ***Housemaid's knee*** - The MRI shows fluid accumulation specifically in the **prepatellar bursa**, which is located anterior to the patella. This finding is the hallmark of prepatellar bursitis. - This condition is colloquially termed **"Housemaid's knee"** as it commonly results from chronic irritation and inflammation of the bursa due to repetitive kneeling. *Subdermal abscess* - A **subdermal abscess** would appear as a collection of pus in the subcutaneous tissue, often with irregular borders and significant surrounding **inflammatory changes (cellulitis)**, which are not the primary findings here. - The fluid collection is well-defined and confined to the anatomical location of the **prepatellar bursa**, not a disorganized subcutaneous collection. *Gout* - Gout typically presents as an acute **intra-articular** inflammation with a large joint effusion. Chronic gout can show characteristic **"rat-bite" erosions** on imaging, which are not visible here. - While gout can cause bursitis, the diagnosis is confirmed by identifying **negatively birefringent urate crystals** in aspirated fluid, and the imaging is less specific than for simple bursitis. *Rheumatoid arthritis* - Rheumatoid arthritis is a systemic disease causing **synovitis** and **pannus formation**, leading to joint destruction and bone erosions, none of which are seen in the image. - While bursitis can be associated with rheumatoid arthritis, it is typically part of a widespread **polyarthritis**, not an isolated finding as shown.

Question 258: Based on the provided X-ray image, identify the most likely diagnosis.

A. Osteosarcoma (Correct Answer)
B. Chondrosarcoma
C. Gout
D. Ewing sarcoma

Explanation: ***Osteosarcoma*** - The X-ray demonstrates a classic **"sunburst"** or **"sun-ray"** appearance, which is a periosteal reaction caused by tumor spicules radiating outwards. This is a hallmark sign of osteosarcoma. - This malignant tumor typically arises in the **metaphysis** of long bones, such as the distal femur, proximal tibia, and proximal humerus, and is often associated with a soft tissue mass and aggressive bone destruction. *Ewing sarcoma* - Radiographically, Ewing sarcoma more commonly presents with a lamellated or **"onion-skin"** periosteal reaction or a destructive, **"moth-eaten"** appearance. - It is a **small round blue cell tumor** that typically affects the **diaphysis** of long bones in children and young adults. *Chondrosarcoma* - This is a malignant tumor of cartilage-producing cells, characterized by **"popcorn"** or **"ring-and-arc"** calcifications on X-ray, which are not seen in this image. - Chondrosarcoma typically affects older adults (over 40) and commonly involves the bones of the pelvis and trunk. *Gout* - Gout is a form of inflammatory arthritis, not a tumor. Its classic radiographic finding is **"punched-out"** erosions with sclerotic margins and overhanging edges, often called **"rat-bite"** erosions. - It does not cause a sunburst periosteal reaction and commonly affects the first metatarsophalangeal joint.

Question 259: Honda or H sign on STIR MRI is characteristic of which condition?

A. Multiple myeloma
B. Sacral insufficiency fracture (Correct Answer)
C. Acute osteomyelitis
D. Bone marrow edema

Explanation: ***Sacral insufficiency fracture*** - The **Honda sign** (also known as the H sign or butterfly sign) is a characteristic finding on **STIR MRI** of the sacrum, particularly suggestive of a **sacral insufficiency fracture** caused by chronic microtrauma in osteoporotic bone. - It represents bilateral vertical fracture lines through the sacral alae connected by a horizontal fracture line through the body of S3 (or S2/S4), showing **medullary edema**/fracture line hyperintensity on STIR sequences. ***Multiple myeloma*** - Myeloma typically presents on MRI as multiple **focal lesions** (plasmacytomas) or diffuse marrow infiltration, often showing low signal intensity on T1 and variable T2/STIR signals. - While sacral involvement is possible, the classic H sign or Honda sign is not a typical presentation; rather, it often shows **lytic lesions** on plain films/CT. ***Acute osteomyelitis*** - Acute osteomyelitis of the sacrum would show localized **marrow edema** with corresponding T1 hypointensity and contrast-enhancing soft tissue/periosteal reaction. - It is usually unilateral and focal, lacking the characteristic H pattern of stress or insufficiency fractures. ***Bone marrow edema*** - Bone marrow edema is a generalized finding on STIR, indicating pathology such as trauma, infection, tumor infiltration, or avascular necrosis (AVN). - While the H sign is a type of bone marrow edema pattern, the sign itself is specific to a **sacral insufficiency fracture**, not a general edema observation.

Question 260: Based on the provided X-ray image, identify the type of thyroid malignancy.

A. Papillary carcinoma
B. Hurthle cell carcinoma
C. Follicular carcinoma (Correct Answer)
D. Thyroid lymphoma

Explanation: ***Follicular carcinoma*** - This is the **correct answer** based on the X-ray showing bone metastases. - Follicular carcinoma characteristically spreads via **hematogenous (bloodstream) route** to distant sites, particularly **bones and lungs**. - Bone metastases from thyroid cancer are **most commonly** due to follicular carcinoma, presenting as **lytic lesions** on X-ray. - Follicular carcinoma accounts for 10-15% of thyroid cancers but is responsible for the majority of thyroid cancer bone metastases. *Incorrect: Papillary carcinoma* - Although papillary carcinoma is the **most common thyroid malignancy** (80% of cases), it predominantly spreads via **lymphatic route** to regional lymph nodes. - Distant hematogenous metastases to bone are **uncommon** in papillary carcinoma. - When papillary carcinoma does metastasize distantly, lungs are more commonly affected than bones. *Incorrect: Hurthle cell carcinoma* - This is an **aggressive variant of follicular carcinoma** (Hürthle cell or oncocytic variant). - While it can spread hematogenously, it is significantly **rarer** than conventional follicular carcinoma. - It represents only 3-5% of differentiated thyroid cancers. *Incorrect: Thyroid lymphoma* - Primary thyroid lymphoma is a **rare malignancy** typically presenting as a rapidly enlarging neck mass. - Usually occurs in elderly patients with a history of **Hashimoto's thyroiditis**. - Distant bone metastases are **not characteristic** of primary thyroid lymphoma.

Practice by Chapter

Radiographic Anatomy of Bones and Joints

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Imaging of Fractures and Dislocations

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Arthritides: Inflammatory and Degenerative

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Metabolic Bone Diseases

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Bone and Soft Tissue Tumors

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Congenital Skeletal Anomalies

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Spine Imaging

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Skeletal Infections

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Sports Medicine Imaging

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Imaging of Prostheses and Implants

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Musculoskeletal Ultrasound

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MSK Interventional Procedures

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