Musculoskeletal Radiology Practice Questions

Q: An X-ray of the skull showing multiple lesions is suggestive of what diagnosis?

Multiple myeloma. ***Multiple myeloma*** - Multiple myeloma classically presents with **multiple, well-demarcated lytic lesions** on a skull X-ray, often described as a **"pepper-pot"** or **"punched-out"** appearance. - These lesions represent areas of bone destruction caused by the proliferation of malignant plasma cells. *Paget disease* - Paget disease typically causes areas of both **bone lysis** and **sclerosis**, leading to a thickened, coarsened trabecular pattern on X-ray, often described as a **"cotton wool"** appearance in the skull. - It usually involves diffuse areas rather than discrete lytic lesions. *Eosinophilic granuloma (Langerhans cell histiocytosis)* - Eosinophilic granuloma can cause **lytic lesions** in the skull, but these are often solitary or multifocal and can have a **beveled edge** appearance. - While possible, it's less common to see the widespread, numerous **"punched-out"** lesions characteristic of multiple myeloma. *Osteomyelitis* - Osteomyelitis of the skull typically presents with **lytic lesions** and surrounding **sclerosis**, often with a more irregular or ill-defined appearance due to inflammation and infection. - It is often associated with clinical signs of infection like fever and localized tenderness, which are not mentioned.

Q: In which condition are Looser's zones typically observed?

Osteomalacia (soft bones). ***Osteomalacia (soft bones)*** - **Looser's zones**, also known as **pseudofractures** or **Milkman's lines**, are a classic radiological sign of osteomalacia. - They represent areas of unmineralized osteoid, which are typically symmetrical, perpendicular to the bone cortex, and penetrate part of the bone. *Osteogenesis imperfecta (brittle bone disease)* - This is a genetic disorder characterized by **fragile bones** due to a defect in **collagen production**. - While patients have frequent fractures, the hallmark radiological findings are not Looser's zones but rather generalized **osteopenia** and **multiple fractures** at various stages of healing. *Osteopetrosis (marble bone disease)* - Osteopetrosis is characterized by **abnormally dense bones** due to defective osteoclast function, leading to a failure of bone resorption. - This condition results in bones that are thick and brittle, often with a **"bone-within-a-bone" appearance** or **Erlenmeyer flask deformities**, not Looser's zones. *Hypoparathyroidism (low parathyroid hormone levels)* - This condition is characterized by **low blood calcium levels** and **high blood phosphate levels** due to insufficient parathyroid hormone. - While it affects bone metabolism, it does not typically manifest with Looser's zones; instead, findings may include **increased bone density** in some cases or normal bone density, along with features related to hypocalcemia such as **basal ganglia calcifications**.

Q: All of the following are radiological signs of scurvy, except which of the following?

Osteoblastoma appearance. ***Osteoblastoma appearance*** - **Osteoblastoma** is a benign bone tumor, NOT a radiological sign of scurvy - Characterized by **bone pain** and appears as a **well-defined lucent lesion with a nidus** on imaging - Completely unrelated to the skeletal changes seen in **vitamin C deficiency** *Trümmerfeld zone* - Refers to the **radiolucent zone of rarefaction** beneath the dense provisional zone of calcification in scurvy - Represents a region of **poorly mineralized, destroyed trabecular bone** - Characteristic sign indicating weakened bone structure due to **vitamin C deficiency** *Frenkel's line (Frankel's white line)* - A **dense, white metaphyseal line** representing abnormally calcified cartilage at the provisional zone of calcification - Results from **impaired osteoid formation** with subsequent abnormal calcification - Classic radiological finding in scurvy due to **defective collagen synthesis** *Pelkan spur (corner sign)* - **Lateral metaphyseal spurs** that appear due to periosteal elevation and subperiosteal hemorrhage - Caused by **fragile capillaries** and **defective collagen synthesis** from vitamin C deficiency - Results in characteristic **corner fractures** with spur-like projections

Q: Flowing candle wax appearance is seen in:

Melorheostosis. ***Melorheostosis*** - This rare sclerosing bone dysplasia is characterized by **unilateral, linear periosteal bone formation** that appears to "flow" down one side of the affected bone, resembling **flowing candle wax**. - The thickened cortical bone follows a **dermatomal distribution**, which is a key diagnostic feature. *Caffey's Disease* - Also known as **infantile cortical hyperostosis**, it causes widespread **bone inflammation and periosteal new bone formation** in infants, most commonly affecting the mandible, clavicles, and long bones. - It does not exhibit the characteristic "flowing candle wax" appearance but rather a more generalized, diffuse cortical thickening. *Parosteal Osteosarcoma* - This is a **low-grade malignant bone tumor** that originates on the outer surface of the bone, with a characteristic dense, lobulated appearance. - While it involves new bone formation, it typically presents as an **exophytic mass** attached to the cortex, not a "flowing candle wax" pattern. *Myositis Ossificans* - This condition involves **heterotopic bone formation within muscle tissue**, usually following trauma. - It presents as a **mass with a distinct calcified rim** and a radiolucent center, evolving into mature bone within soft tissue, rather than a periosteal flowing pattern.

Q: Which of the following is NOT a radiological feature of osteoarthritis?

Subchondral bone is translucent. ***Subchondral bone is translucent*** - This is incorrect because **subchondral bone** in osteoarthritis becomes **sclerotic** and appears **more dense or opaque** radiographically, not translucent, due to increased bone formation as a response to cartilage loss. - **Translucency** would suggest reduced bone density, which is not characteristic of osteoarthritic changes in the subchondral bone. *Osteophytes* - **Osteophytes** (bone spurs) are a hallmark radiological feature of osteoarthritis, representing new bone formation at the joint margins. - They develop as the body attempts to increase the joint's surface area and distribute load more effectively. *Narrowing of joint space* - **Narrowing of the joint space** is a key radiological finding in osteoarthritis, indicating the progressive loss of **articular cartilage**. - This loss reduces the cushioning between bones, leading to direct bone-on-bone contact. *Cystic lesions close to articular surface.* - **Subchondral cysts** (geodes) are common in osteoarthritis, forming as a result of synovial fluid forced into the bone through microscopic cracks in the damaged articular cartilage. - These are typically visible as **radiolucent cystic lesions** adjacent to the joint surface.

Q: Onion peel appearance is seen with:

Small round blue cell tumor. ***Small round blue cell tumor*** - **Onion peel appearance**, or **lamellated periosteal reaction**, is characteristic of a rapidly growing lesion that causes the periosteum to lay down new layers of bone. - This pattern is classically seen in **Ewing sarcoma**, which is a type of small round blue cell tumor. *Giant cell tumor of bone* - Typically presents as a **lytic lesion** with a **soap bubble appearance** on imaging, often found in the epiphysis or metaphysis of long bones. - Does not usually cause an onion peel periosteal reaction. *Cartilaginous tumor* - Imaging features often include a **calcified matrix** with a **ring-and-arc pattern** or lobular configuration, consistent with cartilage production. - Examples like enchondroma or chondrosarcoma do not exhibit an onion peel appearance. *Bone-forming tumor* - While some bone-forming tumors like osteosarcoma can show a periosteal reaction, it's typically a **sunburst pattern** or **Codman triangle**, indicating rapid periosteal elevation. - The classic onion peel appearance specifically points to conditions like Ewing sarcoma, rather than bone-forming tumors generally.

Q: In which condition is the cleavage plane sign typically observed?

Parosteal osteosarcoma. ***Parosteal osteosarcoma*** - The **cleavage plane sign** refers to the presence of a fat-filled or fibrous plane separating the tumor from the underlying cortex, which is characteristic of **parosteal osteosarcoma**. - This sign indicates the **juxtacortical (parosteal) growth pattern** of the tumor, which begins on the bone surface and typically grows outwards. *Ewing's sarcoma* - **Ewing's sarcoma** is a highly aggressive malignant bone tumor that originates in the bone marrow, often presenting with an **"onion-skin" periosteal reaction** due to its intramedullary growth. - It does not typically exhibit a clear cleavage plane between the tumor and the cortex as it grows from within the bone. *Chondrosarcoma* - **Chondrosarcoma** is a malignant tumor of cartilage, often showing **popcorn-like calcifications** and endosteal scalloping, indicating its cartilaginous matrix and intramedullary growth. - While it can be juxtacortical, it does not typically present with a distinct fat or fibrous cleavage plane from the underlying bone like parosteal osteosarcoma. *Metastasis* - **Bone metastases** are secondary cancers that have spread to the bone, often presenting as **lytic or blastic lesions** depending on the primary tumor type. - These lesions typically originate within the bone marrow and invade the bone structure, rather than growing from the surface with a distinct cleavage plane.

Q: In which of the following conditions is the appearance of H-shaped vertebrae not typically observed?

Osteoporosis. ***Osteoporosis*** - While osteoporosis can cause vertebral compression fractures, these generally result in a **wedge-shaped** or **biconcave (fish vertebrae)** appearance, not the distinct **H-shaped vertebrae**. - The characteristic changes in vertebral body morphology due to osteoporosis are primarily related to general **bone demineralization** and fragility, without the specific **central endplate depression** seen in H-shaped vertebrae. *Gaucher's disease* - **Gaucher's disease** is a lysosomal storage disorder that leads to **bone marrow infiltration** by Gaucher cells, causing **ischemia and infarction** of the central vertebral body. - This results in collapse of the central portion with relative preservation of the periphery, leading to the characteristic **H-shaped vertebrae** (also called **Lincoln log vertebrae**) on lateral radiographs. *Osteogenesis Imperfecta* - **Osteogenesis imperfecta** is a genetic disorder characterized by **brittle bones** due to defective type I collagen production, making vertebrae prone to multiple compression fractures. - The typical vertebral deformities include **biconcave (fish) vertebrae** and **platyspondyly** (flattened vertebrae) due to diffuse **osteopenia** and generalized vertebral body collapse, rather than the **central endplate depression** characteristic of H-shaped vertebrae. *Renal Osteodystrophy* - **Renal osteodystrophy** encompasses various bone abnormalities in chronic kidney disease, including **osteomalacia** and **secondary hyperparathyroidism**. - These conditions can lead to weakening and sclerosis of the vertebral endplates. While more commonly associated with **"rugger jersey" spine** (alternating bands of sclerosis), severe cases with central endplate depression can produce **H-shaped vertebrae**, particularly in the presence of associated bone softening.

Q: What is the definitive radiological sign of scurvy observed in an X-ray?

White line in metaphysis. ***White line in metaphysis*** - The **white line of Fraenkel** is a definitive radiological sign of scurvy, representing a dense line of calcified cartilage at the metaphysis due to impaired osteoid formation. - This line indicates normal calcification of cartilage but **defective ossification** by osteoblasts, a hallmark of **vitamin C deficiency**. *Ringed epiphysis* - This sign, also known as the **Wimberger's sign**, refers to a dense ring around the epiphysis, due to calcified cartilage without subsequent bone formation. - While characteristic of scurvy, it is **not considered the most definitive** or specific sign compared to the metaphyseal white line. *Ground glass appearance* - This refers to a generalized **rarefaction of bone** seen in scurvy due to reduced trabecular bone structure. - While present, it is a **non-specific sign** that can be observed in other conditions causing osteopenia. *Thin cortices* - **Cortical thinning** can be observed in scurvy due to compromised periosteal bone formation, contributing to overall skeletal fragility. - However, this is a **general finding in many metabolic bone diseases** and not specific enough to definitively diagnose scurvy.

Q: A 3D CT scan of this patient is shown. What is your conclusion?

Fracture of condyle. ***Fracture of condyle*** - A 3D CT scan revealing an abnormally shaped and displaced condyle strongly indicates a **condylar fracture**. - This type of imaging is highly effective in visualizing bony discontinuities and spatial relationships, which are crucial for diagnosing **condylar fractures**. *Odontomas* - Odontomas are **benign odontogenic tumors** composed of various dental tissues (enamel, dentin, cementum, pulp) and typically appear as radiopaque masses resembling teeth. - They occur within the jaws, unassociated with the morphology of the **condyle**. *Ankylosis of temporomandibular joint* - **TMJ ankylosis** involves a fusion of the mandibular condyle to the temporal bone, often resulting in severe limitation of jaw movement. - While it affects the condyle, it presents as a complete or partial bony fusion, not as a fractured and displaced fragment. *Juvenile rheumatoid arthritis* - **Juvenile rheumatoid arthritis (JRA)** can affect the TMJ, causing destructive changes, flattening of the condyle, erosion, and sometimes growth disturbances. - However, JRA typically presents with degenerative changes rather than an acute, distinct fracture line and displacement seen here.

Question 1

An X-ray of the skull showing multiple lesions is suggestive of what diagnosis?

Accepted Answer

Multiple myeloma

Answer

Osteomyelitis

Answer

Paget disease

Answer

Eosinophilic granuloma (Langerhans cell histiocytosis)

Question 2

In which condition are Looser's zones typically observed?

Accepted Answer

Osteomalacia (soft bones)

Answer

Osteogenesis imperfecta (brittle bone disease)

Answer

Osteopetrosis (marble bone disease)

Answer

Hypoparathyroidism (low parathyroid hormone levels)

Question 3

All of the following are radiological signs of scurvy, except which of the following?

Accepted Answer

Osteoblastoma appearance

Answer

Trummerfeld zone

Answer

Frenkel's line

Answer

Pelican spur

Question 4

Flowing candle wax appearance is seen in:

Accepted Answer

Melorheostosis

Answer

Caffey's Disease

Answer

Parosteal Osteosarcoma

Answer

Myositis Ossificans

Question 5

Which of the following is NOT a radiological feature of osteoarthritis?

Accepted Answer

Subchondral bone is translucent

Answer

Osteophytes

Answer

Cystic lesions close to articular surface.

Answer

Narrowing of joint space

Question 6

Onion peel appearance is seen with:

Accepted Answer

Small round blue cell tumor

Answer

Giant cell tumor of bone

Answer

Cartilaginous tumor

Answer

Bone-forming tumor

Question 7

In which condition is the cleavage plane sign typically observed?

Accepted Answer

Parosteal osteosarcoma

Answer

Ewing's sarcoma

Answer

Chondrosarcoma

Answer

Metastasis

Question 8

In which of the following conditions is the appearance of H-shaped vertebrae not typically observed?

Accepted Answer

Osteoporosis

Answer

Gaucher's disease

Answer

Osteogenesis Imperfecta

Answer

Renal Osteodystrophy

Question 9

What is the definitive radiological sign of scurvy observed in an X-ray?

Accepted Answer

White line in metaphysis

Answer

Ringed epiphysis

Answer

Ground glass appearance

Answer

Thin cortices

Question 10

A 3D CT scan of this patient is shown. What is your conclusion?

Accepted Answer

Fracture of condyle

Answer

Ankylosis of temporomandibular joint

Answer

Odontomas

Answer

Juvenile rheumatoid arthritis

Musculoskeletal Radiology — MCQs

Musculoskeletal Radiology — MCQs

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