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10. Pathology and Oncology MCQs

Practice Set 35 of 351

This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 681

Topic: 10. Pathology and Oncology

A 13-year-old female with a high-grade osteosarcoma of the proximal tibia is undergoing limb salvage. The surgeon plans to perform a Van Nes rotationplasty. What is the primary functional advantage of this procedure compared to a conventional above-knee amputation with a prosthesis?

. Improved cosmetic appearance of the limb.
. Elimination of the need for a prosthetic device.
. Retention of the patient's own ankle joint for active prosthetic knee control.
. Lower risk of infection and mechanical complications.
. Faster rehabilitation and return to full activity.

Correct Answer & Explanation

. Retention of the patient's own ankle joint for active prosthetic knee control.

Explanation

Correct Answer: CExplanation:Van Nes rotationplasty is a specialized limb salvage procedure primarily used for distal femoral or proximal tibial tumors in children. The key functional advantage is the retention of the patient's own ankle joint, which, after being rotated 180 degrees and reattached, functions as a knee joint for a custom-fitted prosthesis. This allows the patient to use their native ankle dorsiflexion and plantarflexion muscles to actively control the prosthetic knee, providing superior proprioception, balance, and endurance compared to a conventional above-knee amputation with a passive or externally powered prosthetic knee. This leads to excellent functional outcomes, especially for active children.A. Improved cosmetic appearance of the limb:Incorrect. Rotationplasty has a unique cosmetic appearance that can be challenging for some patients, though functional outcomes are often prioritized.B. Elimination of the need for a prosthetic device:Incorrect. A prosthesis is still required for the lower leg and foot, but it is a more functional prosthesis.D. Lower risk of infection and mechanical complications:Rotationplasty has its own set of potential complications, including non-union, nerve issues, and skin problems, and does not inherently have a lower risk of infection or mechanical issues compared to other complex reconstructions.E. Faster rehabilitation and return to full activity:Rehabilitation is extensive and prolonged, similar to other complex limb salvage procedures.

Question 682

Topic: Bone Tumors

Which of the following conditions is most strongly associated with the development of secondary osteosarcoma in the craniofacial bones, particularly the jaw, in older adults?

. Fibrous dysplasia
. Hereditary retinoblastoma
. Multiple hereditary exostoses
. Paget's disease of bone
. Ollier's disease

Correct Answer & Explanation

. Paget's disease of bone

Explanation

Correct Answer: DExplanation:Paget's disease of boneis a well-recognized predisposing factor for the development of secondary osteosarcoma, especially in older adults. The craniofacial bones, including the maxilla and mandible (jaw), are common sites for Paget's disease. Therefore, osteosarcoma arising in the jaw in an older adult should raise suspicion for underlying Paget's disease. These secondary osteosarcomas generally carry a worse prognosis than conventional osteosarcomas.A. Fibrous dysplasia:While fibrous dysplasia can rarely undergo malignant transformation into osteosarcoma, it is not the most common predisposing factor for jaw osteosarcoma in older adults.B. Hereditary retinoblastoma:This condition is associated with germline RB1 mutations and a significantly increased risk of osteosarcoma, but typically in younger individuals and not specifically localized to the jaw.C. Multiple hereditary exostoses (HME):HME is a genetic disorder predisposing to the development of multiple osteochondromas, which can transform into chondrosarcoma, not osteosarcoma.E. Ollier's disease (multiple enchondromatosis):Similar to HME, Ollier's disease is associated with multiple enchondromas and carries a risk of malignant transformation into chondrosarcoma, not osteosarcoma.

Question 683

Topic: 10. Pathology and Oncology

A 10-year-old male presents with an incidental finding of a lucent lesion in the distal femur. Radiographs show an eccentric, lobulated, sclerotic-rimmed lesion in the metaphysis. Which of the following statements regarding the natural history of this likely diagnosis is most accurate?

. It typically progresses to an aggressive osteosarcoma in adulthood.
. It often spontaneously resolves by skeletal maturity, with osseous remodeling.
. Surgical excision is always indicated due to high risk of malignant transformation.
. It is a precursor lesion to Paget's disease of bone.
. It commonly recurs after surgical curettage.

Correct Answer & Explanation

. It often spontaneously resolves by skeletal maturity, with osseous remodeling.

Explanation

Correct Answer: BNon-ossifying fibroma (NOF) is a benign, self-limiting fibrous lesion that characteristically regresses spontaneously, often filling in with normal bone by skeletal maturity. Malignant transformation is exceedingly rare to non-existent. Surgical excision is not always indicated and is reserved for specific situations like impending or actual pathological fracture. It is not a precursor to osteosarcoma or Paget's disease, and recurrence after complete curettage is uncommon.

Question 684

Topic: 10. Pathology and Oncology

A biopsy from a well-circumscribed, eccentrically located metaphyseal lesion in a child reveals spindle cells arranged in a storiform pattern, admixed with multinucleated giant cells and hemosiderin deposition. These histological features are most characteristic of which of the following?

. Chondroblastoma
. Giant Cell Tumor
. Non-ossifying Fibroma
. Osteoid Osteoma
. Fibrous Dysplasia

Correct Answer & Explanation

. Non-ossifying Fibroma

Explanation

Correct Answer: CThe classic histological description of a non-ossifying fibroma (NOF) includes a proliferation of benign spindle cells, often arranged in a storiform (pinwheel or cartwheel) pattern, admixed with scattered multinucleated giant cells, foam cells (lipid-laden macrophages), and areas of hemosiderin deposition. Chondroblastoma has chondroblast-like cells. Giant cell tumor lacks the storiform pattern and has uniform giant cells. Osteoid osteoma has osteoid seams. Fibrous dysplasia has woven bone in a fibrous stroma.

Question 685

Topic: Bone Tumors

Which of the following best describes the typical radiographic appearance of a Non-Ossifying Fibroma on a plain X-ray?

. Central calcification with a periosteal reaction.
. Permeative osteolytic lesion with soft tissue mass.
. Well-defined, eccentric, lytic lesion with a sclerotic margin and often multiloculated appearance.
. Sunburst periosteal reaction with Codman's triangle.
. Ground-glass matrix with endosteal scalloping.

Correct Answer & Explanation

. Well-defined, eccentric, lytic lesion with a sclerotic margin and often multiloculated appearance.

Explanation

Correct Answer: CNOFs typically present as well-defined, eccentric, purely lytic lesions with a characteristic sclerotic margin. They often have a lobulated or 'bubbly' appearance, indicating fibrous septa. Cortical thinning and mild expansion are also common. The other options describe features of other bone tumors (osteosarcoma for B and D, fibrous dysplasia for E, and calcification for enchondroma).

Question 686

Topic: 10. Pathology and Oncology

A 12-year-old boy has an asymptomatic 4 cm non-ossifying fibroma of the proximal tibia, incidentally discovered on radiographs for knee pain attributed to Osgood-Schlatter disease. The cortical involvement is approximately 30%. What is the most appropriate initial management?

. Immediate curettage and bone grafting
. Prophylactic internal fixation
. Serial radiographic observation
. Biopsy to rule out malignancy
. Radiation therapy

Correct Answer & Explanation

. Serial radiographic observation

Explanation

Correct Answer: CFor asymptomatic non-ossifying fibromas (NOFs) that are less than 50% of the cortical diameter and not associated with an impending or actual pathological fracture, the most appropriate initial management is serial radiographic observation. NOFs are benign and often regress spontaneously. Surgical intervention (curettage, grafting) is reserved for larger lesions (typically >50% cortical involvement), symptomatic lesions, or those with pathological fracture risk. Biopsy is generally not needed if characteristic radiographic features are present in the appropriate age group. Radiation therapy is contraindicated for benign bone lesions.

Question 687

Topic: 10. Pathology and Oncology

A 14-year-old competitive soccer player sustains a pathological fracture through a 6 cm non-ossifying fibroma located in the distal femoral metaphysis. The lesion involves approximately 60% of the cortical circumference. After initial immobilization, what is the most appropriate next step in management?

. Continued conservative management with cast immobilization until union
. Open biopsy followed by aggressive chemotherapy
. Intralesional steroid injection
. Curettage and bone grafting, with or without internal fixation
. Amputation

Correct Answer & Explanation

. Curettage and bone grafting, with or without internal fixation

Explanation

Correct Answer: DA pathological fracture through a large non-ossifying fibroma (NOF), especially one involving more than 50% of the cortex, is a clear indication for surgical intervention. While conservative management might be considered for small, non-displaced fractures through very small lesions, a 6 cm lesion with 60% cortical involvement and a fracture warrants curettage and bone grafting. Internal fixation may be added to provide stability and protect the construct, especially in a young, active individual. Chemotherapy and amputation are inappropriate for a benign lesion. Intralesional steroids are used for other benign lesions like unicameral bone cysts, not NOF.

Question 688

Topic: 10. Pathology and Oncology

Which of the following is crucial to include in the differential diagnosis of a large, expansile, lytic metaphyseal lesion in a child, alongside NOF, particularly if fluid-fluid levels are noted on MRI?

. Osteomyelitis
. Ewing's Sarcoma
. Aneurysmal Bone Cyst (ABC)
. Enchondroma
. Chordoma

Correct Answer & Explanation

. Aneurysmal Bone Cyst (ABC)

Explanation

Correct Answer: CAneurysmal Bone Cyst (ABC) is a critical differential diagnosis for a large, expansile, lytic metaphyseal lesion, especially in children and if fluid-fluid levels are present on MRI, as these are highly characteristic of ABCs. While other options like Ewing's sarcoma are important for malignant lesions, and enchondromas for cartilaginous lesions, ABC mimics NOF's lucent, expansile nature and shares the pediatric age group. Osteomyelitis can be lytic but usually has other signs of infection. Chordoma typically affects the axial skeleton.

Question 689

Topic: 10. Pathology and Oncology

What is the primary differentiating feature between a Fibrous Cortical Defect (FCD) and a Non-Ossifying Fibroma (NOF)?

. FCDs are always symptomatic, while NOFs are asymptomatic.
. NOFs exhibit malignant transformation, FCDs do not.
. FCDs are typically smaller and purely cortical, while NOFs are larger and extend into the medullary cavity.
. FCDs occur in adults, NOFs in children.
. They have completely different histological appearances.

Correct Answer & Explanation

. FCDs are typically smaller and purely cortical, while NOFs are larger and extend into the medullary cavity.

Explanation

Correct Answer: CFCDs and NOFs are considered to be part of the same spectrum of fibrous lesions. The primary distinction is size and medullary extension: FCDs are smaller (<2-3 cm) and primarily cortical, whereas NOFs are larger and typically extend into the medullary cavity, often representing a later stage of FCD. Histologically, they are identical. Both are benign and typically asymptomatic, occurring in children.

Question 690

Topic: 10. Pathology and Oncology

Which of the following statements regarding the malignant transformation of Non-Ossifying Fibroma is true?

. It frequently transforms into low-grade osteosarcoma.
. It has a high risk of transforming into fibrosarcoma.
. Malignant transformation has been well-documented in multiple cases.
. Malignant transformation is extremely rare, with only anecdotal reports, if any, being generally unconvincing.
. It transforms into Ewing's sarcoma in 5-10% of cases.

Correct Answer & Explanation

. Malignant transformation is extremely rare, with only anecdotal reports, if any, being generally unconvincing.

Explanation

Correct Answer: DMalignant transformation of a Non-Ossifying Fibroma (NOF) is exceedingly rare, to the point where most authorities consider it practically non-existent or, at best, based on highly controversial or anecdotal reports lacking definitive proof. There is no established risk of malignant transformation into osteosarcoma, fibrosarcoma, or Ewing's sarcoma. This lack of malignant potential is a key feature in its benign nature.

Question 691

Topic: 10. Pathology and Oncology

A 14-year-old boy completes neoadjuvant chemotherapy for conventional osteosarcoma of the distal femur followed by wide surgical resection. Pathological analysis of the resected specimen is performed. Which of the following is the most important prognostic factor for his long-term overall survival?

. Surgical margin width greater than 2 cm
. Percentage of tumor necrosis
. Tumor volume at initial presentation
. Presence of an osteoblastic versus chondroblastic subtype
. Duration of symptoms prior to biopsy

Correct Answer & Explanation

. Percentage of tumor necrosis

Explanation

The most significant prognostic factor for conventional osteosarcoma is the percentage of tumor necrosis following neoadjuvant chemotherapy. According to the Huvos grading system, greater than 90% tumor necrosis indicates a good response and significantly correlates with improved long-term survival.

Question 692

Topic: Bone Tumors

A 9-year-old girl is evaluated for multiple eccentrically located, radiolucent, metaphyseal lesions with sclerotic margins in her bilateral lower extremities. Physical examination reveals multiple cafe-au-lait macules. She has a documented history of developmental delay. Which of the following is the most likely diagnosis?

. Neurofibromatosis type 1
. McCune-Albright syndrome
. Jaffe-Campanacci syndrome
. Mazabraud syndrome
. Ollier disease

Correct Answer & Explanation

. Jaffe-Campanacci syndrome

Explanation

Jaffe-Campanacci syndrome is characterized by the triad of multiple non-ossifying fibromas (NOFs), cafe-au-lait macules, and intellectual disability or hypogonadism. While neurofibromatosis type 1 also presents with cafe-au-lait spots, it is not classically associated with multiple NOFs.

Question 693

Topic: 10. Pathology and Oncology

A 65-year-old man presents with severe thigh pain after a minor trip. Radiographs show a displaced subtrochanteric fracture through a lytic lesion with intralesional stippled calcifications. MRI reveals a large, unmineralized soft tissue mass extending from the bony lesion. Biopsy shows a sharp, distinct transition between low-grade hyaline cartilage and a high-grade undifferentiated spindle cell sarcoma. What is the most likely diagnosis?

. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Telangiectatic osteosarcoma
. Dedifferentiated chondrosarcoma
. Secondary conventional chondrosarcoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a bimorphic histological pattern showing a distinct border between a low-grade cartilaginous tumor and a high-grade non-cartilaginous sarcoma (e.g., osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma). It carries a very poor prognosis and commonly presents with a pathological fracture.

Question 694

Topic: 10. Pathology and Oncology

A 28-year-old female complains of a painless, slow-growing mass in her posterior distal thigh. Radiographs demonstrate a dense, lobulated, ossified mass attached to the posterior cortex of the distal femur by a broad base, with a radiolucent cleft separating part of the tumor from the underlying bone. Histology reveals well-formed bone trabeculae within a low-grade fibroblastic stroma. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Wide surgical resection alone
. Neoadjuvant chemotherapy followed by wide resection
. Primary external beam radiation therapy
. Marginal excision with phenol adjuvant

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

The clinical and radiographic presentation describes a parosteal osteosarcoma, which is a low-grade surface osteosarcoma. Due to its low-grade nature, it is highly resistant to chemotherapy and radiation, making wide surgical resection the treatment of choice.

Question 695

Topic: 10. Pathology and Oncology

A 10-year-old boy who plays competitive soccer is found incidentally to have an eccentric, cortically based, lytic lesion with a sclerotic rim in the distal tibial metaphysis. Radiographs show the lesion occupies 60% of the transverse bone diameter and is 40 mm in length. He complains of mild, occasional pain localized to the area after intense running. What is the most appropriate management?

. Reassurance and unrestricted return to activity
. Non-weight-bearing casting for 4 weeks
. Prophylactic curettage and bone grafting
. Wide surgical resection and endoprosthetic reconstruction
. Core needle biopsy followed by observation

Correct Answer & Explanation

. Prophylactic curettage and bone grafting

Explanation

While non-ossifying fibromas (NOFs) are typically observed, prophylactic curettage and bone grafting are indicated if the lesion occupies greater than 50% of the bone diameter, is larger than 33 mm, or becomes painful. These criteria suggest a high risk for impending pathological fracture.

Question 696

Topic: 10. Pathology and Oncology

A 35-year-old male presents with chronic hip pain. Radiographs show an epiphyseal, mildly expansile, lytic lesion with intralesional calcification in the proximal femur. Histology demonstrates cells with abundant clear cytoplasm, distinct cell membranes, and areas of hyaline cartilage, admixed with multinucleated giant cells. Which of the following is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Chondromyxoid fibroma
. Giant cell tumor of bone
. Aneurysmal bone cyst

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a low-grade malignant cartilage tumor that distinctively occurs in the epiphysis, mimicking chondroblastoma radiographically. However, it typically presents in patients aged 20-50, whereas chondroblastomas present in skeletally immature patients, and its histology features classic clear cells.

Question 697

Topic: 10. Pathology and Oncology

A 12-year-old girl is diagnosed with a conventional high-grade osteosarcoma of the proximal tibia. Her family history is significant for a father who died of an adrenocortical carcinoma and an aunt with early-onset breast cancer. A germline mutation in which of the following genes is most likely responsible for this patient's presentation?

. RB1
. EXT1
. TP53
. GNAS
. PTEN

Correct Answer & Explanation

. TP53

Explanation

The patient's family history of early-onset breast cancer, adrenocortical carcinoma, and osteosarcoma is classic for Li-Fraumeni syndrome. This autosomal dominant disorder is caused by a germline mutation in the TP53 tumor suppressor gene.

Question 698

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with progressive knee swelling. MRI reveals an expansile, metaphyseal lesion in the distal femur with multiple fluid-fluid levels. However, close inspection of the MRI shows thick, nodular peripheral septations. Biopsy demonstrates blood-filled spaces lined by highly pleomorphic, atypical mononuclear cells producing a fine, lace-like osteoid matrix. What is the most appropriate treatment?

. Doxycycline sclerotherapy
. Intralesional curettage and bone grafting
. Preoperative denosumab followed by curettage
. Neoadjuvant chemotherapy and wide resection
. Primary external beam radiation therapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy and wide resection

Explanation

The clinical, radiographic, and histological findings describe telangiectatic osteosarcoma, which can easily be mistaken for a benign aneurysmal bone cyst due to fluid-fluid levels. Because it is a high-grade malignancy, the standard of care is neoadjuvant chemotherapy followed by wide surgical resection.

Question 699

Topic: 10. Pathology and Oncology

A 42-year-old man with a known history of multiple hereditary exostoses (MHE) reports recent growth and pain in a previously stable mass on his proximal humerus. MRI demonstrates an osteochondroma with a cartilaginous cap thickness of 2.5 cm. Which of the following genetic mechanisms is most directly associated with his underlying syndrome?

. Activating mutation in the GNAS gene
. Inactivation of the EXT1 or EXT2 tumor suppressor genes
. Overexpression of the MDM2 gene
. IDH1 or IDH2 point mutations
. Chromosomal translocation t(11;22)

Correct Answer & Explanation

. Inactivation of the EXT1 or EXT2 tumor suppressor genes

Explanation

Multiple hereditary exostoses (MHE) is an autosomal dominant disorder caused by mutations in the EXT1 or EXT2 genes, which are involved in heparan sulfate synthesis. A cartilage cap thicker than 1.5-2.0 cm in an adult with MHE is highly suspicious for secondary malignant transformation to chondrosarcoma.

Question 700

Topic: 10. Pathology and Oncology

A 19-year-old female presents with swelling on the anterior aspect of her mid-tibia. Radiographs show a broad-based, surface radiolucency with extrinsic cortical scalloping, Codman triangles, and perpendicular spicules of bone (sunburst pattern). Core biopsy reveals an intermediate-grade spindle cell proliferation with prominent cartilage production and areas of fine, lace-like malignant bone formation. What is the diagnosis?

. Parosteal osteosarcoma
. Periosteal osteosarcoma
. Periosteal chondroma
. High-grade surface osteosarcoma
. Conventional chondrosarcoma

Correct Answer & Explanation

. Periosteal osteosarcoma

Explanation

Periosteal osteosarcoma typically arises on the surface of the diaphysis (often the anterior tibia), appearing as an intermediate-grade tumor with a predominant chondroblastic matrix. Unlike parosteal osteosarcoma, it is more commonly diaphyseal, higher grade (intermediate), and often exhibits a "hair-on-end" or sunburst periosteal reaction.

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