Menu

Bone Tumors MCQs

Practice Set 35 of 52

This practice set contains high-yield board review questions covering key concepts in Bone Tumors. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 681

Topic: Bone Tumors

Which of the following is an expected radiographic finding for a low-grade conventional chondrosarcoma?

. Extensive Codman's triangle.
. Hair-on-end periosteal reaction.
. Well-circumscribed lytic lesion with punctate/ring-and-arc calcifications and endosteal scalloping.
. Sunburst periosteal reaction.
. Sclerotic lesion with a thick, benign-appearing periosteal reaction.

Correct Answer & Explanation

. Well-circumscribed lytic lesion with punctate/ring-and-arc calcifications and endosteal scalloping.

Explanation

Low-grade conventional chondrosarcomas commonly present radiographically as well-circumscribed lytic lesions with characteristic punctate or ring-and-arc calcifications (representing mineralized cartilaginous matrix) and varying degrees of endosteal scalloping, indicating internal bone erosion. Codman's triangle, hair-on-end, and sunburst periosteal reactions are typical of more aggressive lesions like osteosarcoma or Ewing sarcoma. A thick, benign-appearing periosteal reaction might suggest chronic osteomyelitis or a healing fracture, not a chondrosarcoma.

Question 682

Topic: Bone Tumors

What is the most common histological variant of chondrosarcoma?

. Clear cell chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Dedifferentiated chondrosarcoma.
. Conventional chondrosarcoma.
. Juxtacortical chondrosarcoma.

Correct Answer & Explanation

. Conventional chondrosarcoma.

Explanation

Conventional chondrosarcoma is by far the most common histological variant, accounting for approximately 85-90% of all chondrosarcomas. The other variants (clear cell, mesenchymal, dedifferentiated, juxtacortical/periosteal) are relatively rare.

Question 683

Topic: Bone Tumors

Which of the following statements about radiation therapy for chondrosarcoma is true?

. Conventional chondrosarcoma is highly radiosensitive and radiation is the primary treatment.
. Radiation therapy is contraindicated in all forms of chondrosarcoma.
. Mesenchymal chondrosarcoma and dedifferentiated chondrosarcoma may show some response to radiation due to their more aggressive, less differentiated components.
. Radiation therapy is effective for local control of Grade I lesions but not higher grades.
. Radiation therapy is used exclusively for palliation of pain in metastatic disease.

Correct Answer & Explanation

. Mesenchymal chondrosarcoma and dedifferentiated chondrosarcoma may show some response to radiation due to their more aggressive, less differentiated components.

Explanation

While conventional chondrosarcoma is generally considered radioresistant, mesenchymal chondrosarcoma and the high-grade components of dedifferentiated chondrosarcoma can show some responsiveness to radiation therapy due to their more undifferentiated nature and higher cellularity. Therefore, radiation may be considered as an adjuvant or for unresectable disease in these specific variants. Radiation is not the primary treatment for conventional chondrosarcoma and is not contraindicated in all forms. It can be used for local control in some unresectable cases, not just for Grade I, and its role is not limited to palliation in metastatic disease, although that is one application.

Question 684

Topic: Bone Tumors

What is the characteristic appearance of a dedifferentiated chondrosarcoma on imaging?

. A uniformly well-circumscribed lesion with punctate calcifications.
. A purely sclerotic lesion with benign periosteal reaction.
. A biphasic appearance with a chondroid component juxtaposed with a destructive, aggressive lytic soft tissue mass.
. A lesion primarily affecting the epiphysis with clear cell morphology.
. A broad-based sessile lesion arising from the cortical surface.

Correct Answer & Explanation

. A biphasic appearance with a chondroid component juxtaposed with a destructive, aggressive lytic soft tissue mass.

Explanation

Dedifferentiated chondrosarcoma typically presents with a biphasic imaging appearance, reflecting its histology. It shows features of a conventional chondrosarcoma (chondroid matrix, calcifications) adjacent to or within a more aggressive, destructive lytic lesion with cortical destruction and a significant soft tissue mass, representing the high-grade non-cartilaginous component. A uniformly well-circumscribed lesion or sclerotic lesion would suggest a low-grade or benign lesion. Epiphyseal clear cell morphology is for clear cell chondrosarcoma. A broad-based sessile lesion is characteristic of juxtacortical chondrosarcoma or osteochondroma.

Question 685

Topic: Bone Tumors

Which molecular alteration is commonly associated with peripheral chondrosarcomas arising from osteochondromas?

. IDH1/IDH2 mutations.
. TP53 mutations.
. EXT1/EXT2 mutations.
. H3F3A mutations.
. COL2A1 mutations.

Correct Answer & Explanation

. EXT1/EXT2 mutations.

Explanation

Peripheral chondrosarcomas, which arise from pre-existing osteochondromas (especially in Multiple Hereditary Exostoses), are strongly associated with inactivating mutations in the EXT1 and EXT2 genes. These genes are involved in heparan sulfate biosynthesis and are linked to the development of osteochondromas. While IDH1/IDH2 mutations are common in central chondrosarcomas and enchondromas, EXT1/EXT2 are specific to the osteochondroma pathway of malignant transformation.

Question 686

Topic: Bone Tumors

Which of the following describes the most common type of chondrosarcoma to affect the small bones of the hands and feet?

. Dedifferentiated chondrosarcoma.
. Mesenchymal chondrosarcoma.
. Periosteal chondrosarcoma.
. Secondary chondrosarcoma arising from a solitary osteochondroma.
. Secondary chondrosarcoma arising from enchondromatosis (e.g., Ollier's disease).

Correct Answer & Explanation

. Secondary chondrosarcoma arising from enchondromatosis (e.g., Ollier's disease).

Explanation

While conventional chondrosarcoma can occur in the small bones, malignant transformation of enchondromas, particularly in the context of enchondromatosis (Ollier's disease or Maffucci's syndrome), is the most common cause of chondrosarcoma in the small bones of the hands and feet. These typically present as low-grade chondrosarcomas. Other variants are less common in these locations.

Question 687

Topic: Bone Tumors

A 12-year-old is undergoing limb salvage surgery for a distal femoral osteosarcoma. The surgeon plans to use an expandable endoprosthesis. What is the main advantage of this type of implant in a growing child?

. Lower risk of infection compared to other implants.
. It allows for limb lengthening to compensate for growth discrepancies.
. Superior bone integration due to porous coating.
. It eliminates the need for future revision surgeries.
. Reduced cost compared to fixed-length prostheses.

Correct Answer & Explanation

. It allows for limb lengthening to compensate for growth discrepancies.

Explanation

Expandable endoprostheses (also known as growing prostheses or modular growing prostheses) are designed to lengthen over time, either surgically or non-invasively, to match the growth of the contralateral limb. This is their main advantage in skeletally immature patients, as it helps prevent significant limb length discrepancy. They do not inherently have a lower infection risk, superior bone integration (unless specifically designed with unique coatings), or eliminate the need for future revisions (they often have a limited lifespan). They are typically more expensive than fixed-length prostheses due to their complex mechanisms.

Question 688

Topic: Bone Tumors

Which osteosarcoma subtype is most likely to be purely lytic on radiographs, often mimicking an aneurysmal bone cyst, and typically has a very aggressive clinical course?

. Parosteal osteosarcoma
. Periosteal osteosarcoma
. High-grade surface osteosarcoma
. Telangiectatic osteosarcoma
. Low-grade central osteosarcoma

Correct Answer & Explanation

. Telangiectatic osteosarcoma

Explanation

Telangiectatic osteosarcoma is a rare but highly aggressive variant characterized by a predominantly lytic, hemorrhagic, and cystic appearance, often leading to misdiagnosis as an aneurysmal bone cyst. It shows minimal osteoid formation. Parosteal and periosteal osteosarcomas are surface tumors, with parosteal being low-grade and periosteal intermediate-grade, both with distinct features and generally better prognosis than conventional osteosarcoma. High-grade surface osteosarcoma is also aggressive but usually has some visible matrix. Low-grade central osteosarcoma is rare and has a better prognosis but is still an intramedullary lesion.

Question 689

Topic: Bone Tumors

Which of the following conditions is a known predisposing factor for the development of secondary osteosarcoma in adults?

. Fibrous dysplasia
. Multiple enchondromatosis (Ollier's disease)
. Osteomyelitis
. Paget's disease of bone
. Osteopetrosis

Correct Answer & Explanation

. Paget's disease of bone

Explanation

Paget's disease of bone is a well-established risk factor for the development of secondary osteosarcoma, especially in elderly patients. The risk is estimated to be less than 1% but is significantly higher than in the general population. Other conditions like post-radiation therapy, fibrous dysplasia, bone infarcts, and chronic osteomyelitis (rarely) can also predispose to secondary osteosarcoma, but Paget's disease is a classic association. Multiple enchondromatosis (Ollier's disease) and Maffucci syndrome are associated with chondrosarcoma. Fibrous dysplasia very rarely transforms into osteosarcoma. Osteomyelitis itself is not a direct predisposing factor for osteosarcoma.

Question 690

Topic: Bone Tumors

Which of the following conditions most commonly presents with osteosarcoma of the jaw, often in older adults?

. Li-Fraumeni syndrome
. Hereditary retinoblastoma
. Paget's disease of bone
. Multiple hereditary exostoses
. Fibrous dysplasia

Correct Answer & Explanation

. Paget's disease of bone

Explanation

Osteosarcomas of the jaw (mandible and maxilla) are distinct from appendicular osteosarcomas. They tend to occur in older adults and have different biological behaviors and prognoses. While Li-Fraumeni and hereditary retinoblastoma predispose to osteosarcoma, they are not specifically associated with a higher incidence in the jaw compared to the skeleton overall, and usually present at a younger age. Paget's disease of bone is a strong predisposing factor for secondary osteosarcoma in older adults, and the craniofacial skeleton (including the jaw) is a common site for Paget's disease. Therefore, Paget's disease is the most common predisposing factor for osteosarcoma of the jaw in older adults. MHE is linked to chondrosarcoma. Fibrous dysplasia can rarely undergo malignant transformation, but it's not the most common predisposing factor for jaw osteosarcoma in this age group.

Question 691

Topic: Bone Tumors

A 16-year-old male presents with a painful mass in his distal femur. Radiographs show a dense, lobulated lesion arising from the external cortical surface, with a characteristic 'string sign' separating it from the underlying cortex. What is the most likely diagnosis?

. Conventional osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Parosteal osteosarcoma
. Periosteal osteosarcoma

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

The description of a dense, lobulated lesion arising from the external cortical surface, with a 'string sign' (a radiolucent line between the tumor and the underlying cortex), is pathognomonic for parosteal osteosarcoma. This subtype is typically low-grade, grows slowly, and has a much better prognosis than conventional osteosarcoma. Conventional osteosarcoma is intramedullary and aggressive. Chondrosarcoma produces cartilaginous matrix. Ewing sarcoma shows an 'onion-skin' periosteal reaction and usually a purely lytic appearance. Periosteal osteosarcoma is also a surface osteosarcoma but originates from the periosteum, has an intermediate grade, is less ossified, and lacks the 'string sign'.

Question 692

Topic: Bone Tumors

Which component of the chemotherapy regimen for osteosarcoma is associated with hemorrhagic cystitis, and what prophylactic agent is used to prevent it?

. Methotrexate; Leucovorin
. Cisplatin; Amifostine
. Doxorubicin; Dexrazoxane
. Ifosfamide; Mesna
. Etoposide; Filgrastim

Correct Answer & Explanation

. Ifosfamide; Mesna

Explanation

Ifosfamide is an alkylating agent commonly used in osteosarcoma treatment, and its primary dose-limiting toxicity is hemorrhagic cystitis, caused by the metabolite acrolein. Mesna (2-mercaptoethane sulfonate sodium) is a uroprotectant that inactivates acrolein in the bladder, thereby preventing hemorrhagic cystitis. Leucovorin rescues from methotrexate toxicity. Amifostine reduces nephrotoxicity from cisplatin. Dexrazoxane protects against doxorubicin-induced cardiotoxicity. Filgrastim is a G-CSF used for myelosuppression, not specific to etoposide.

Question 693

Topic: Bone Tumors

What is the primary mechanism of action of Cisplatin in the treatment of osteosarcoma?

. Inhibition of dihydrofolate reductase
. Intercalation into DNA, leading to strand breaks
. Cross-linking DNA, forming adducts that inhibit DNA synthesis and repair
. Microtubule stabilization, inhibiting cell division
. Topoisomerase I inhibition

Correct Answer & Explanation

. Cross-linking DNA, forming adducts that inhibit DNA synthesis and repair

Explanation

Cisplatin is an alkylating-like agent (a platinum-based compound). Its primary mechanism of action involves binding to DNA and forming intra- and inter-strand cross-links and adducts. These DNA adducts interfere with DNA replication and transcription, ultimately leading to apoptosis. Methotrexate inhibits dihydrofolate reductase. Doxorubicin intercalates into DNA and inhibits topoisomerase II. Taxanes (like paclitaxel) stabilize microtubules. Topoisomerase I inhibitors include irinotecan and topotecan.

Question 694

Topic: Bone Tumors

A patient with osteosarcoma develops new onset hearing loss and tinnitus during chemotherapy. Which agent is the most likely culprit?

. Methotrexate
. Ifosfamide
. Doxorubicin
. Cisplatin
. Cyclophosphamide

Correct Answer & Explanation

. Cisplatin

Explanation

Cisplatin is well-known for its ototoxicity, causing sensorineural hearing loss (tinnitus and high-frequency hearing loss) which can be permanent and cumulative. It also causes nephrotoxicity and peripheral neuropathy. Methotrexate causes renal toxicity and mucositis. Ifosfamide causes hemorrhagic cystitis and neurotoxicity. Doxorubicin causes cardiotoxicity. Cyclophosphamide is associated with hemorrhagic cystitis (like ifosfamide) and myelosuppression.

Question 695

Topic: Bone Tumors

Which osteosarcoma variant is considered an intermediate-grade surface tumor, typically presenting in the diaphysis of long bones with a cartilaginous cap and less aggressive behavior than conventional osteosarcoma?

. Parosteal osteosarcoma
. Periosteal osteosarcoma
. High-grade surface osteosarcoma
. Intracortical osteosarcoma
. Telangiectatic osteosarcoma

Correct Answer & Explanation

. Periosteal osteosarcoma

Explanation

Periosteal osteosarcoma is an intermediate-grade surface osteosarcoma that typically arises from the periosteum, often found in the diaphysis of long bones (especially tibia and femur). It has a predominantly chondroblastic differentiation, presenting with a cartilaginous cap and spiculated periosteal reaction. Its prognosis is generally better than conventional osteosarcoma but worse than parosteal osteosarcoma. Parosteal is low-grade. High-grade surface osteosarcoma is aggressive. Intracortical osteosarcoma is rare. Telangiectatic is intramedullary and highly aggressive.

Question 696

Topic: Bone Tumors

What is the typical age range for the primary peak incidence of conventional osteosarcoma?

. Under 5 years old
. 5-10 years old
. 10-25 years old
. 30-50 years old
. Over 60 years old

Correct Answer & Explanation

. 10-25 years old

Explanation

Conventional osteosarcoma has a bimodal age distribution, with the primary and largest peak incidence occurring in adolescents and young adults, typically between 10 and 25 years of age. A second, smaller peak occurs in older adults, often associated with predisposing factors like Paget's disease or prior radiation therapy. It is uncommon in very young children or middle-aged adults without predisposing factors.

Question 697

Topic: Bone Tumors

After surgical resection of a high-grade osteosarcoma, what is the recommended frequency and duration for surveillance chest CT scans to detect pulmonary metastases?

. Annually for 5 years, then every 2 years.
. Every 6 months for 2 years, then annually for 3 years.
. Every 3 months for 2 years, then every 6 months for 3 years, then annually up to 10 years.
. Only if symptoms of pulmonary metastasis develop.
. Every 2 years for life.

Correct Answer & Explanation

. Every 3 months for 2 years, then every 6 months for 3 years, then annually up to 10 years.

Explanation

The most common site of recurrence for osteosarcoma is the lung, usually within the first 2-3 years post-treatment. A rigorous surveillance protocol is crucial. A common recommendation is chest CT scans every 3 months for the first 2 years, then every 6 months for the next 3 years, and then annually up to 10 years or longer, depending on the institution and risk factors. The goal is early detection of resectable metastases to improve survival. Waiting for symptoms would be too late for curative metastasectomy.

Question 698

Topic: Bone Tumors

What is the most effective imaging modality for detecting early pulmonary metastases in a patient undergoing surveillance for osteosarcoma?

. Plain chest X-ray
. CT scan of the chest
. MRI of the chest
. PET/CT scan
. Ultrasound of the chest

Correct Answer & Explanation

. CT scan of the chest

Explanation

A CT scan of the chest is the most effective and sensitive imaging modality for detecting early, small pulmonary metastases from osteosarcoma. Plain chest X-rays have poor sensitivity for small nodules. MRI and PET/CT can detect pulmonary nodules but are typically not used as the primary routine surveillance tool due to cost, accessibility, and artifact issues (MRI) or radiation dose (PET/CT for frequent use). Ultrasound has no role in detecting lung metastases.

Question 699

Topic: Bone Tumors

What is the primary concern for a growing child undergoing limb salvage with a conventional, fixed-length endoprosthesis after resection of a distal femoral osteosarcoma?

. Risk of prosthetic loosening.
. Long-term infection risk.
. Development of significant limb length discrepancy.
. Lack of sensory feedback in the reconstructed limb.
. Poor cosmetic outcome.

Correct Answer & Explanation

. Development of significant limb length discrepancy.

Explanation

In a skeletally immature patient, a conventional, fixed-length endoprosthesis does not grow, while the contralateral limb continues to grow. This will inevitably lead to a significant limb length discrepancy over time, requiring multiple revision surgeries for lengthening or contralateral limb shortening. This is a major concern. Loosening and infection are risks for any endoprosthesis, but limb length discrepancy is specific to the growing child with a fixed implant. Lack of sensory feedback is common to all prostheses, and cosmetic outcome is a factor, but not the primary concern related to 'fixed-length' in a 'growing child'.

Question 700

Topic: Bone Tumors

A patient with a distal femoral osteosarcoma, initially treated with limb salvage, develops a local recurrence in the residual bone proximal to the endoprosthesis. What is the most appropriate next step in management?

. Systemic chemotherapy alone, as local recurrence is a sign of widespread disease.
. Palliative radiation therapy to the recurrence site.
. Surgical wide resection of the recurrence, possibly requiring amputation.
. Observation with serial imaging to assess growth rate.
. Intra-arterial chemotherapy to the limb.

Correct Answer & Explanation

. Surgical wide resection of the recurrence, possibly requiring amputation.

Explanation

Local recurrence of osteosarcoma, particularly if resectable, warrants aggressive surgical management, often involving a wider resection that may necessitate amputation if limb salvage is no longer feasible with adequate margins. While systemic therapy may be part of the overall plan, surgical removal of the recurrence offers the best chance for local control and potentially improved survival. Local recurrence is not always indicative of widespread disease and may still be curable. Palliative radiation might be considered if surgery is not an option, and observation is inappropriate for an aggressive recurrence.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page