Bone Tumors Practice Questions

Q: Spot the diagnosis based on the given X-ray of hand.

Enchondroma. ***Enchondroma*** - The X-ray image shows a **lucent, well-defined lesion** within the shaft of the 5th metacarpal bone, accompanied by some **cortical thinning** but largely preserved cortex. This appearance, particularly in the small bones of the hand, is classic for an enchondroma. - Enchondromas are benign cartilaginous tumors, often found incidentally, and their radiographic features include a **radiolucent geographic lesion** with occasional internal calcifications, though not clearly visible here. *Osteoid osteoma* - An osteoid osteoma typically presents as a small **lucid nidus less than 1.5 cm** surrounded by a prominent rim of **sclerotic bone**. - While it can occur in the hand, the lesion in the image is larger and lacks the characteristic central nidus with reactive sclerosis. *Simple bone cysts* - Simple bone cysts (also known as unicameral bone cysts) are typically **lucent, centrally located lesions** often found in the **metaphysis of long bones**. - They tend to be large and usually lack internal calcifications or the characteristic lobulated appearance seen in this lesion. *Chloroma* - A chloroma (also known as granulocytic sarcoma) is a solid tumor of **myeloid blasts**, typically associated with leukemia. - On X-ray, they usually present as **lytic bone lesions** that can cause bone destruction and soft tissue involvement, which is not consistent with the well-defined, lytic but contained lesion shown.

Q: A 20-year-old college girl presents with pain in the upper part of tibia especially after dance classes. The pain has increased to a level that she cannot practice for forthcoming college festival. X-ray of the lower leg shows:

Osteoblastoma. ***Osteoblastoma*** - On X-ray, osteoblastomas commonly appear as a **lytic lesion** with a **sclerotic rim**, often larger than 2 cm, which can be seen in the provided image. The pain in the **tibia** that worsens with activity and affects a young individual is also consistent with the presentation of osteoblastoma. - This benign bone tumor is known to cause significant localized pain and can be found in the **metaphysis or diaphysis** of long bones like the tibia. *Osteosarcoma* - Osteosarcoma is a **highly aggressive malignant bone tumor** that typically presents with a **"sunburst" or "Codman's triangle"** appearance and areas of amorphous calcification (osteoid matrix) on X-ray, which are not clearly evidenced here. - While it can occur in young adults and cause pain, the radiographic findings are more indicative of a benign lytic lesion. *Chondrosarcoma* - Chondrosarcoma is a **malignant cartilaginous tumor** often characterized by **"rings and arcs"** or **popcorn-like calcifications** within a lytic lesion on X-ray, typical of cartilage matrix. - While it can cause pain, its radiographic features are distinct from those observed. *Pigmented villonodular synovitis* - This is a **benign proliferative disorder of the synovium** affecting joints or bursae, not primarily the bone itself. - It would typically demonstrate **erosions** and **soft tissue masses** within a joint on imaging, not a lytic bone lesion as shown.

Q: Comment on the diagnosis of the presentation shown below:

Unicameral bone cyst. ***Unicameral bone cyst*** - This X-ray shows a **well-defined, lytic lesion** in the proximal humerus, consistent with a unicameral bone cyst, often presenting in the **metaphysis** of long bones in children and adolescents. - The lesion has a **thin, sclerotic rim** and shows **no significant periosteal reaction** or soft tissue mass, which are classic features. *Aneurysmal bone cyst* - While also a lytic lesion, an aneurysmal bone cyst typically appears more **expansile** and **multiloculated**, often with a **"soap bubble" appearance**. - It usually has a **thicker, more irregular rim** and can present with faster growth or more aggressive features than a unicameral bone cyst. *Osteoblastoma* - Osteoblastomas are typically **osteoblastic (bone-forming)** tumors, which would appear more **sclerotic** or mixed lytic-sclerotic on X-ray, rather than a purely lytic lesion like the one shown. - They commonly affect the **spine or long bones**, but their radiographic appearance of predominant bone formation is not seen here. *Osteoclastoma* - Osteoclastomas, also known as **giant cell tumors of bone**, are usually found in the **epiphysis** of long bones in mature skeletons, which is a different location than observed. - They are typically **aggressive lytic lesions** with poorly defined margins and can extend to the articular surface, which is not characteristic of the well-demarcated lesion in the image.

Q: All are correct about the condition shown in X-ray except:

Needle biopsy. **Needle biopsy** - **Needle biopsy** is generally **contraindicated** in cases of suspected or confirmed osteosarcoma due to the risk of **tumor seeding** along the biopsy tract or increasing the risk of metastasis. - Diagnosis is typically established via **open biopsy** to obtain a larger and more representative tumor sample for histopathological analysis. *Elevated ESR* - An **elevated Erythrocyte Sedimentation Rate (ESR)** is a common finding in many inflammatory conditions and malignancies, including osteosarcoma. - It reflects the body's generalized inflammatory response to the tumor. *Increased uptake in bone scan* - **Increased uptake** in a **bone scan** (using technetium-99m) is characteristic of osteosarcoma due to the tumor's high **osteoblastic activity** and increased bone turnover. - This increased metabolic activity leads to increased radionuclide accumulation in the affected area. *Appears 2 weeks postinjury* - A fracture or minor injury can sometimes be the initial event that brings an underlying osteosarcoma to clinical attention, as the tumor can **weaken the bone** making it more susceptible to fracture. - However, the image shows a lytic lesion, which is typical of osteosarcoma, and not necessarily a fracture appearing 2 weeks post-injury; the tumor itself may have been developing for a longer period.

Q: Identify the lesion in the X-ray shown below:

Aneurysmal bone cyst. ***Aneurysmal bone cyst*** - The image shows a **lytic, expansile lesion** in the distal radius with a **"soap bubble" appearance**, characteristic of an aneurysmal bone cyst. - These are typically **benign, blood-filled lesions** that cause bone remodeling and expansion. *Giant cell tumour* - While also a **lytic lesion**, giant cell tumors are usually more aggressive and often show **cortical destruction** and less distinct margins without the typical septations seen here. - They tend to occur in the **epiphysis** of long bones after epiphyseal closure. *Osteoma* - An osteoma is a **benign, dense, sclerotic bone growth**, appearing as a very bright, compact lesion on X-ray, which is clearly not depicted in the image. - These are typically **asymptomatic** and found incidentally. *Osteosarcoma* - This is a **highly malignant primary bone tumor** that typically presents with a **blastic or mixed lytic-blastic appearance**, often with a **"sunburst" pattern** or **Codman's triangle**, characteristics not seen in this image. - It usually causes significant **cortical destruction** and a more aggressive soft tissue mass.

Q: The most likely diagnosis for the lesion shown in the image is:

Giant cell tumour. ***Giant cell tumour*** - The image shows an **epiphyseal lytic lesion** in the distal femur that extends to the subchondral bone, which is characteristic of a giant cell tumour. - Giant cell tumours are usually **benign but locally aggressive**, often presenting in patients aged 20-40 years and typically involve the **epiphysis** of long bones, most commonly around the knee. *Unicameral bone cyst* - These are typically **metaphyseal lesions**, often seen in children and adolescents, and are usually **lucent** with a thin sclerotic rim. - They often present with a **"fallen fragment sign"** if there's a pathological fracture, which is not visible here. *Aneurysmal bone cyst* - An aneurysmal bone cyst is usually a **multiloculated, expansile, lytic lesion** that can be metaphyseal or diaphyseal, most commonly found in patients under 20 years old. - While it can be destructive, it typically has a **fluid-fluid level** on MRI due to blood products, which is not appreciable on this plain radiograph, and its common location differs. *Osteoid osteoma* - An osteoid osteoma is a small, benign tumour characterized by a **small radiolucent nidus** (typically less than 1.5 cm) surrounded by a large area of **sclerosis**. - It usually presents with **pain that improves with NSAIDs**, and its radiographic appearance is distinctly different from the large lytic lesion shown.

Q: The following hallmarks characterise Diaphyseal aclasis except

Chondrosarcoma may occur in less than 1% cases. ***Chondrosarcoma may occur in less than 1% cases*** - This statement is incorrect as the risk of malignant transformation to **chondrosarcoma** in Diaphyseal aclasis (hereditary multiple exostoses) is commonly reported to be significantly higher, ranging from **5-25%**. - Therefore, stating it occurs in "less than 1% cases" is factually inaccurate, making this the correct answer as to what does *not* characterize the condition. *Pseudoarthrosis is common* - **Pseudoarthrosis** (false joint formation) can occur as a complication of **bony deformities** and the presence of osteochondromas, particularly in regions where they interfere with bone growth or cause fractures. - The abnormal growth of osteochondromas can predispose to fractures, which may heal poorly and result in pseudoarthrosis. *It is inherited as an autosomal dominant dysplasia* - Diaphyseal aclasis, also known as **hereditary multiple exostoses (HME)**, is indeed an **autosomal dominant** skeletal dysplasia. - It is caused by mutations in the **EXT1 or EXT2 genes**, which are involved in heparan sulfate proteoglycan synthesis, leading to abnormal bone growth. *Genu valgum can be found* - **Genu valgum** (knock-knees) is a common **skeletal deformity** observed in individuals with Diaphyseal aclasis. - The multiple osteochondromas can disturb the normal growth and alignment of long bones, frequently affecting the distal femur and proximal tibia leading to this angular deformity.

Q: The most common site for osteosarcoma is:

Distal femur. ***Distal femur*** - The **distal femur** is the most frequent site of involvement for **osteosarcoma**, accounting for approximately 40% of all cases [1]. - This region, along with the proximal tibia and proximal humerus, constitutes the most common locations for this primary malignant bone tumor [1]. *Proximal humerus* - While the **proximal humerus** is a common site for osteosarcoma, it is less frequent than the distal femur [1]. - It ranks third in incidence after the distal femur and proximal tibia [1]. *Proximal femur* - The **proximal femur** can be affected by osteosarcoma, but it is a relatively less common site compared to the distal femur. - Osteosarcomas tend to occur around the **growth plates** of long bones [1]. *Distal humerus* - The **distal humerus** is an uncommon site for the development of osteosarcoma. - It is much less frequently involved than the other major long bone metaphyses. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1200-1202.

Q: The image shows a wrist deformity and an X-ray of a bone lesion near the distal radius. Based on the clinical and radiological features, what is the most likely diagnosis?

Giant Cell Tumor (GCT). ***Giant Cell Tumor (GCT)*** * The image shows a **lytic (lucid) lesion** located in the **epiphysis/metaphysis of the distal radius**, which is a classic presentation site for GCT. * GCTs are typically seen in individuals aged 20-40, often present with **pain, swelling, and reduced range of motion**, and can show a **soap bubble appearance** on X-ray even with cortical erosion as seen in the image. *Ewing's Sarcoma* * Ewing's Sarcoma commonly affects the **diaphysis of long bones** and may present with an **onion skin periosteal reaction**, none of which are clearly depicted. * It primarily affects children and young adults (5-20 years old), which does not align with the assumed adult presentation given the fused epiphysis. *Osteochondroma* * Osteochondromas are **bony prominences covered by cartilage** and grow **outward from the bone surface**, often away from the joint, unlike the intraosseous lytic lesion seen. * They typically appear as **pedunculated or sessile exostoses** and are benign growth plate abnormalities, not lytic lesions of the marrow cavity. *Osteoid Osteoma* * Osteoid osteomas are characterized by a **small lucent nidus** (usually <1.5 cm) surrounded by a significant margin of **sclerotic bone**, which is not seen here. * They classically cause **nocturnal pain** relieved by NSAIDs and are typically smaller than the lesion depicted, which appears expansile.

Q: A 14 year old male presents with mushroom like tumor in the distal femur for past 2 years. Which of the following features suggest malignant transformation?

Cartilage thickness $>2 \mathrm{~cm}$. ***Cartilage thickness >2 cm*** - A **cartilage cap thickness greater than 2 cm** in an osteochondroma in an adult (or >3 cm in children) is a strong indicator of **malignant transformation** into a secondary peripheral **chondrosarcoma**. [2], [3] - **Key imaging finding:** Cartilage cap measured on MRI or CT scan - Other features suggesting malignant transformation include continued growth after skeletal maturity, new or increasing pain, cortical destruction, and new soft tissue mass. [2], [3] *Presence of cartilage cap* - All osteochondromas have a cartilage cap by definition - this is a normal feature, not a sign of malignancy. [1] - The **thickness** of the cap, not its presence, is what matters. *Location in metaphysis* - Osteochondromas typically arise from the metaphysis near the growth plate - this is a normal location. [3] - Location alone does not indicate malignant transformation. *Size less than 1 cm* - Small size suggests a benign, stable lesion. - Malignant transformation is suggested by **increasing size** and growth after skeletal maturity, not small size. [2] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1202. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 672-673. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1202-1204.

Question 1

Spot the diagnosis based on the given X-ray of hand.

Accepted Answer

Enchondroma

Answer

Osteoid osteoma

Answer

Simple bone cysts

Answer

Chloroma

Question 2

A 20-year-old college girl presents with pain in the upper part of tibia especially after dance classes. The pain has increased to a level that she cannot practice for forthcoming college festival. X-ray of the lower leg shows:

Accepted Answer

Osteoblastoma

Answer

Osteosarcoma

Answer

Chondrosarcoma

Answer

Pigmented villonodular synovitis

Question 3

Comment on the diagnosis of the presentation shown below:

Accepted Answer

Unicameral bone cyst

Answer

Aneurysmal bone cyst

Answer

Osteoblastoma

Answer

Osteoclastoma

Question 4

All are correct about the condition shown in X-ray except:

Accepted Answer

Needle biopsy

Answer

Elevated ESR

Answer

Increased uptake in bone scan

Answer

Appears 2 weeks postinjury

Question 5

Identify the lesion in the X-ray shown below:

Accepted Answer

Aneurysmal bone cyst

Answer

Giant cell tumour

Answer

Osteoma

Answer

Osteosarcoma

Question 6

The most likely diagnosis for the lesion shown in the image is:

Accepted Answer

Giant cell tumour

Answer

Unicameral bone cyst

Answer

Aneurysmal bone cyst

Answer

Osteoid osteoma

Question 7

The following hallmarks characterise Diaphyseal aclasis except

Accepted Answer

Chondrosarcoma may occur in less than 1% cases

Answer

Pseudoarthrosis is common

Answer

It is inherited as an autosomal dominant dysplasia

Answer

Genu valgum can be found

Question 8

The most common site for osteosarcoma is:

Accepted Answer

Distal femur

Answer

Proximal humerus

Answer

Proximal femur

Answer

Distal humerus

Question 9

The image shows a wrist deformity and an X-ray of a bone lesion near the distal radius. Based on the clinical and radiological features, what is the most likely diagnosis?

Accepted Answer

Giant Cell Tumor (GCT)

Answer

Ewings Sarcoma

Answer

Osteochondroma

Answer

Osteoid Osteoma

Question 10

A 14 year old male presents with mushroom like tumor in the distal femur for past 2 years. Which of the following features suggest malignant transformation?

Accepted Answer

Cartilage thickness $>2 \mathrm{~cm}$

Answer

Presence of cartilage cap

Answer

Location in metaphysis

Answer

Size less than 1 cm

Bone Tumors — MCQs

Bone Tumors — MCQs

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