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10. Pathology and Oncology MCQs

Practice Set 53 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 1041

Topic: 10. Pathology and Oncology

A 35-year-old male with a known history of Multiple Hereditary Exostoses presents with a newly enlarging, painful mass over his proximal humerus. MRI demonstrates an osteochondroma with a thickened cartilage cap. A cartilage cap thicker than what measurement in a skeletally mature adult is highly suspicious for secondary malignant transformation?

. 2 mm
. 5 mm
. 10 mm
. 20 mm
. 30 mm

Correct Answer & Explanation

. 20 mm

Explanation

In adults, a cartilage cap thickness greater than 2 cm (20 mm) on MRI is highly concerning for malignant transformation of an osteochondroma into a secondary peripheral chondrosarcoma. Pain and interval growth in a skeletally mature patient are critical clinical warning signs.

Question 1042

Topic: Bone Tumors

A 14-year-old boy presents with a symptomatic pedunculated osteochondroma on the distal medial femur causing snapping of the pes anserinus tendons. Which of the following is the most critical technical principle when excising this lesion to prevent recurrence?

. Removing the mass with a 2 cm margin of normal underlying medullary bone
. Proceeding with a thorough intralesional curettage
. Excision of the entire cartilage cap and overlying perichondrium
. Using adjuvant cryotherapy in the residual bony defect
. Immediate prophylactic internal fixation of the femur to prevent fracture

Correct Answer & Explanation

. Excision of the entire cartilage cap and overlying perichondrium

Explanation

Recurrence of an osteochondroma after surgical excision is rare but typically occurs due to incomplete removal of the cartilage cap or the overlying perichondrium. Complete excision at the base of the stalk, ensuring the entire cartilage cap and perichondrium are removed, is essential.

Question 1043

Topic: 10. Pathology and Oncology

Following the meticulous repair of a severe nail matrix laceration, what is the primary rationale for replacing the native nail plate (or placing a synthetic stent) into the proximal eponychial fold?

. To provide rigid fixation for an underlying tuft fracture
. To prevent the formation of a subungual glomus tumor
. To prevent synechiae formation between the eponychial roof and the germinal matrix
. To stimulate accelerated nail plate growth via mechanical pressure
. To completely seal the matrix from bacterial contamination

Correct Answer & Explanation

. To prevent synechiae formation between the eponychial roof and the germinal matrix

Explanation

Stenting the proximal nail fold with the native nail plate or a synthetic substitute prevents the eponychial roof from adhering to the germinal matrix (synechiae), which would otherwise obstruct normal nail plate outgrowth.

Question 1044

Topic: 10. Pathology and Oncology

A 58-year-old male presents with a 9-month history of dull, intermittent pain in his right proximal femur, which has recently become more constant and bothersome at night. He denies any trauma. Physical examination reveals mild tenderness over the greater trochanter. Radiographs are shown below:

Based on the imaging, which of the following is the most appropriate next step in management?

. Observation with repeat radiographs in 3 months.
. Empiric non-steroidal anti-inflammatory drugs (NSAIDs) and physical therapy.
. CT-guided core needle biopsy of the lesion.
. Intralesional curettage of the lesion.
. Immediate wide en bloc resection.

Correct Answer & Explanation

. CT-guided core needle biopsy of the lesion.

Explanation

Correct Answer: CThe patient's age, insidious onset of pain (especially night pain), and the radiographic findings (lytic lesion with internal punctate/ring-and-arc calcifications, cortical thickening, and potential endosteal scalloping) are highly suspicious for a low-grade conventional central chondrosarcoma. Given these suspicious features, a definitive diagnosis is required before proceeding with definitive treatment. A CT-guided core needle biopsy is the most appropriate next step to confirm the diagnosis, determine the histological grade, and guide subsequent surgical planning.Option A (Observation)is inappropriate for a symptomatic, suspicious lesion.Option B (NSAIDs and physical therapy)addresses symptoms but delays definitive diagnosis and treatment of a potentially malignant tumor.Option D (Intralesional curettage)is an inadequate treatment for chondrosarcoma, especially if it's Grade 2 or higher, and should only be considered in very select, low-grade, well-contained lesions, often with adjuvant therapy, and only after a confirmed diagnosis.Option E (Immediate wide en bloc resection)is the definitive treatment for chondrosarcoma but should only be performed after a confirmed diagnosis and thorough staging, as the extent of resection depends on the tumor's grade and local extent.

Question 1045

Topic: 10. Pathology and Oncology

A 45-year-old female presents with a slowly enlarging, painless mass on the medial aspect of her distal femur. She has a known history of Hereditary Multiple Exostoses. Radiographs show a sessile osteochondroma with a cartilaginous cap measuring 2.5 cm in thickness on MRI, as depicted below:

What is the most appropriate management for this lesion?

. Observation with annual MRI scans.
. CT-guided core needle biopsy of the cartilaginous cap.
. Wide en bloc resection of the osteochondroma including the cartilaginous cap.
. Intralesional curettage of the cartilaginous cap.
. Adjuvant radiation therapy followed by marginal excision.

Correct Answer & Explanation

. Wide en bloc resection of the osteochondroma including the cartilaginous cap.

Explanation

Correct Answer: CIn a patient with Hereditary Multiple Exostoses, an enlarging, painful, or asymptomatic lesion with a cartilaginous cap thickness exceeding 1-2 cm (2.5 cm in this case) is highly suspicious for malignant transformation into a secondary peripheral chondrosarcoma. The most appropriate management is a wide en bloc resection of the entire osteochondroma, including its cartilaginous cap and underlying stalk, to achieve clear surgical margins.Option A (Observation)is inappropriate given the high suspicion of malignancy.Option B (CT-guided core needle biopsy)could be considered, but given the clear indication of malignant transformation (cap thickness), definitive excision is often preferred as it is both diagnostic and therapeutic. Biopsy of cartilaginous tumors can also be challenging for accurate grading.Option D (Intralesional curettage)is inadequate for chondrosarcoma and carries a high risk of local recurrence.Option E (Adjuvant radiation therapy followed by marginal excision)is generally ineffective for conventional chondrosarcoma, and marginal excision is associated with high recurrence rates.

Question 1046

Topic: 10. Pathology and Oncology

A 62-year-old male undergoes an unplanned intralesional excision for what was initially thought to be a benign enchondroma of the proximal tibia. Final pathology, however, reveals a Grade 2 conventional chondrosarcoma with positive surgical margins. The patient is otherwise healthy. What is the most appropriate next step in management?

. Observation with serial MRI scans every 3 months.
. Adjuvant external beam radiation therapy to the surgical site.
. Systemic chemotherapy to prevent recurrence.
. Planned re-excision with wide surgical margins.
. Palliative care and pain management.

Correct Answer & Explanation

. Planned re-excision with wide surgical margins.

Explanation

Correct Answer: DAn unplanned intralesional excision of a Grade 2 chondrosarcoma with positive surgical margins is a critical oncologic error. The primary goal for chondrosarcoma is local control through wide en bloc resection with clear margins. Given the positive margins and the tumor's grade, a planned re-excision with wide surgical margins is absolutely necessary to achieve local control and prevent recurrence.Option A (Observation)is inadequate and would almost certainly lead to local recurrence.Option B (Adjuvant external beam radiation therapy)is generally ineffective for conventional chondrosarcoma due to its radioresistance.Option C (Systemic chemotherapy)is also largely ineffective for conventional chondrosarcoma and is not a substitute for adequate surgical margins.Option E (Palliative care)is inappropriate for a resectable Grade 2 chondrosarcoma where curative treatment is still possible.

Question 1047

Topic: 10. Pathology and Oncology

Which of the following histological features is most characteristic of a Grade 1 conventional central chondrosarcoma, making its differentiation from a benign enchondroma particularly challenging?

. Abundant mitotic figures and prominent nuclear pleomorphism.
. Presence of a high-grade spindle cell component.
. Bland chondrocytes with small, uniform nuclei, but with increased cellularity and occasional binucleation compared to enchondroma.
. Extensive areas of tumor necrosis.
. Formation of osteoid or immature bone within the cartilaginous matrix.

Correct Answer & Explanation

. Bland chondrocytes with small, uniform nuclei, but with increased cellularity and occasional binucleation compared to enchondroma.

Explanation

Correct Answer: CThe histological differentiation between a benign enchondroma and a low-grade (Grade 1) conventional chondrosarcoma is notoriously challenging. Grade 1 chondrosarcoma is characterized by bland chondrocytes with small, uniform nuclei, but often shows increased cellularity, occasional binucleation, and subtle nuclear atypia compared to a typical enchondroma. Mitotic figures are rare or absent.Option A (Abundant mitotic figures and prominent nuclear pleomorphism)andOption D (Extensive areas of tumor necrosis)are features of higher-grade chondrosarcomas (Grade 2 or 3) or dedifferentiated chondrosarcoma.Option B (Presence of a high-grade spindle cell component)would suggest a dedifferentiated chondrosarcoma or another type of sarcoma.Option E (Formation of osteoid or immature bone within the cartilaginous matrix)would indicate an osteosarcoma or a dedifferentiated chondrosarcoma with an osteosarcomatous component.

Question 1048

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a painful, rapidly growing mass in his maxilla. Imaging reveals a destructive lesion with both cartilaginous and soft tissue components. Biopsy findings are shown below:

Histopathology reveals a biphasic tumor composed of primitive small round cells and islands of well-differentiated hyaline cartilage, with a prominent hemangiopericytoma-like vascular pattern. What is the most likely diagnosis?

. Conventional central chondrosarcoma Grade 1
. Clear cell chondrosarcoma
. Dedifferentiated chondrosarcoma
. Mesenchymal chondrosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Correct Answer: DThe description of a biphasic tumor with primitive small round cells, islands of well-differentiated hyaline cartilage, and a hemangiopericytoma-like vascular pattern is pathognomonic for mesenchymal chondrosarcoma. This rare variant frequently occurs in axial sites, including the craniofacial bones (like the maxilla in this case), spine, and pelvis, and typically affects younger patients.Option A (Conventional central chondrosarcoma Grade 1)would primarily show bland chondrocytes in a cartilaginous matrix without a prominent small round cell component.Option B (Clear cell chondrosarcoma)is characterized by polygonal cells with clear cytoplasm, typically in epiphyseal locations.Option C (Dedifferentiated chondrosarcoma)involves a sharp transition from a low-grade conventional chondrosarcoma to a high-grade non-cartilaginous sarcoma, but not typically with the small round cell and hemangiopericytoma pattern.Option E (Chondroblastoma)is a benign epiphyseal tumor with characteristic 'chicken wire' calcifications and chondroblast-like cells, but lacks the biphasic malignant features described.

Question 1049

Topic: 10. Pathology and Oncology

A 70-year-old male with a history of a resected Grade 1 conventional chondrosarcoma of the proximal humerus 5 years ago presents with a rapidly growing, painful mass at the previous surgical site. Imaging shows a large, destructive lesion with significant soft tissue extension. Biopsy reveals a high-grade undifferentiated pleomorphic sarcoma. What is the most likely diagnosis?

. Local recurrence of Grade 1 conventional chondrosarcoma.
. Post-radiation sarcoma.
. Dedifferentiated chondrosarcoma.
. Metastatic carcinoma.
. Benign reactive process.

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma.

Explanation

Correct Answer: CThis scenario describes the classic presentation of dedifferentiated chondrosarcoma. It is characterized by the abrupt juxtaposition of a well-differentiated conventional chondrosarcoma component (often low-grade, as in the patient's history) with a high-grade, non-cartilaginous sarcoma component (e.g., osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma, as seen in the biopsy). This transformation leads to a much more aggressive clinical course and a very poor prognosis.Option A (Local recurrence of Grade 1 conventional chondrosarcoma)would imply a recurrence with similar low-grade cartilaginous features, not a high-grade pleomorphic sarcoma.Option B (Post-radiation sarcoma)would require a history of radiation therapy to the site, which is not mentioned.Option D (Metastatic carcinoma)is less likely given the history of a primary bone sarcoma at the same site.Option E (Benign reactive process)is inconsistent with a rapidly growing, destructive mass and high-grade sarcoma histology.

Question 1050

Topic: 10. Pathology and Oncology

A 68-year-old male with Ollier's disease (multiple enchondromatosis) develops increasing pain and a palpable mass in his left ilium. Imaging reveals enlargement and increased mineralization of an existing enchondroma-like lesion, with cortical destruction and soft tissue extension. Which of the following genetic mutations is most commonly associated with the malignant transformation seen in this patient?

. TP53
. EXT1/EXT2
. IDH1/IDH2
. H3F3B
. SMAD4

Correct Answer & Explanation

. IDH1/IDH2

Explanation

Correct Answer: CPatients with Ollier's disease and Maffucci syndrome have a significantly increased risk of developing conventional central chondrosarcoma, which arises from the malignant transformation of their benign enchondromas. Somatic mutations in Isocitrate Dehydrogenase 1 and 2 (IDH1/IDH2) genes are highly prevalent in enchondromas and conventional central chondrosarcomas, including those associated with Ollier's disease and Maffucci syndrome. These mutations are considered early oncogenic drivers in chondrosarcoma development.Option A (TP53)is a tumor suppressor gene involved in many cancers but not specifically linked to enchondromatoses.Option B (EXT1/EXT2)mutations are associated with Hereditary Multiple Exostoses (HME) and secondary peripheral chondrosarcoma, not Ollier's disease.Option D (H3F3B)mutations are associated with clear cell chondrosarcoma.Option E (SMAD4)is associated with juvenile polyposis syndrome and other gastrointestinal cancers.

Question 1051

Topic: 10. Pathology and Oncology

A 50-year-old patient undergoes wide en bloc resection for a Grade 2 conventional chondrosarcoma of the proximal femur. Postoperative MRI at 6 months shows no evidence of local recurrence. What is the most appropriate long-term follow-up strategy for this patient?

. No further imaging is needed if the patient remains asymptomatic.
. Annual chest X-ray for 5 years, then biannually.
. MRI of the local site and CT scan of the chest every 6-12 months for 5-10 years.
. Bone scintigraphy (bone scan) annually indefinitely.
. CT scan of the abdomen and pelvis every 6 months for 2 years.

Correct Answer & Explanation

. MRI of the local site and CT scan of the chest every 6-12 months for 5-10 years.

Explanation

Correct Answer: CFollow-up for resected chondrosarcoma, especially Grade 2 or higher, requires diligent surveillance for both local recurrence and distant metastases. The lungs are the most common site of metastasis for chondrosarcoma. Therefore, a combination of local imaging (MRI of the surgical site) and chest imaging (CT is more sensitive than X-ray for detecting lung metastases) is standard. This surveillance is typically performed every 6-12 months for 5-10 years, depending on the tumor grade and initial staging.Option A (No further imaging)is negligent for a malignant tumor.Option B (Annual chest X-ray)is insufficient as X-rays have lower sensitivity for small lung nodules compared to CT.Option D (Bone scintigraphy annually indefinitely)is not the primary modality for detecting local recurrence or lung metastases, though it can be used for bone metastases.Option E (CT scan of the abdomen and pelvis)might be included for very large axial tumors, but chest CT is paramount for lung metastases, and abdomen/pelvis alone is insufficient.

Question 1052

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a large, destructive mass in his sacrum, causing progressive neurological symptoms including bowel and bladder dysfunction. Biopsy confirms a Grade 3 conventional chondrosarcoma. The orthopedic oncologist determines that achieving wide surgical margins would necessitate a high sacrectomy, likely resulting in permanent neurological deficits. What is the biggest challenge in treating this specific presentation?

. The inherent resistance of chondrosarcoma to chemotherapy.
. The high metastatic potential of Grade 3 chondrosarcoma.
. Achieving wide surgical margins without causing unacceptable neurological morbidity.
. Difficulty in obtaining an accurate histological grade from the biopsy.
. Lack of suitable prosthetic reconstruction options for the sacrum.

Correct Answer & Explanation

. Achieving wide surgical margins without causing unacceptable neurological morbidity.

Explanation

Correct Answer: CThe biggest challenge in treating sacral chondrosarcomas, especially large, destructive, or high-grade lesions, is achieving wide surgical margins without causing unacceptable neurological deficits (e.g., permanent bowel/bladder dysfunction, severe lower extremity weakness). The complex anatomy of the sacrum, with its close proximity to vital neurovascular structures and the spinal cord, makes radical resection extremely difficult. This often leads to marginal or intralesional excisions, which are associated with high local recurrence rates.Option A (Resistance to chemotherapy)is true for conventional chondrosarcoma, but the primary challenge in this specific anatomical location is surgical.Option B (High metastatic potential)is also true for Grade 3 lesions, but the immediate and most pressing challenge for a resectable tumor in this location is local control.Option D (Difficulty in histological grading)is generally not the biggest challenge, as biopsies can usually provide a grade.Option E (Lack of suitable prosthetic reconstruction options)is a concern, but achieving oncologically sound margins takes precedence over reconstruction, which is secondary.

Question 1053

Topic: 10. Pathology and Oncology

What is the primary reason for the inherent resistance of conventional central chondrosarcoma to conventional systemic chemotherapy and external beam radiation therapy?

. Rapid proliferation rate of chondrocytes.
. High expression of multi-drug resistance proteins.
. Poor vascularity and hypoxic environment of cartilaginous tissue.
. Lack of specific growth factor receptors targeted by current drugs.
. Inability of drugs to penetrate the dense cartilaginous matrix.

Correct Answer & Explanation

. Poor vascularity and hypoxic environment of cartilaginous tissue.

Explanation

Correct Answer: CThe primary reason for the resistance of conventional chondrosarcoma to both chemotherapy and radiation therapy is attributed to the inherent poor vascularity and hypoxic environment of cartilaginous tissue. This avascular nature limits the delivery of chemotherapeutic agents to the tumor cells and reduces the effectiveness of radiation, which relies on oxygen-dependent free radical formation to damage DNA.Option A (Rapid proliferation rate)is incorrect; conventional chondrosarcomas generally have a slow growth rate.Option B (High expression of multi-drug resistance proteins)can play a role in some tumors, but the fundamental tissue characteristic of cartilage is more significant.Option D (Lack of specific growth factor receptors)is a factor in drug development but not the primary reason for general resistance to conventional therapies.Option E (Inability of drugs to penetrate the dense cartilaginous matrix)is related to poor vascularity but is a consequence rather than the primary cause.

Question 1054

Topic: 10. Pathology and Oncology

A 14-year-old male presents with right distal femoral pain and swelling for 3 months. Radiographs reveal a lytic and blastic lesion in the metaphysis with a Codman's triangle and sunburst periosteal reaction. What is the most common chromosomal abnormality associated with conventional osteosarcoma?

. t(11;22) EWSR1-FLI1 translocation
. CDK4 amplification
. TP53 mutation
. RUNX1 translocation
. HER2 overexpression

Correct Answer & Explanation

. TP53 mutation

Explanation

Correct Answer: CWhile all options relate to genetic abnormalities, TP53 mutations (Li-Fraumeni syndrome) and RB1 gene mutations (retinoblastoma) are the most commonly identified genetic alterations in sporadic conventional osteosarcoma. TP53 is a tumor suppressor gene, and its inactivation is crucial in osteosarcoma development. EWSR1-FLI1 is characteristic of Ewing sarcoma. CDK4 amplification is seen in atypical lipomatous tumor/well-differentiated liposarcoma. RUNX1 translocations are associated with some leukemias. HER2 overexpression can occur but is not the most common chromosomal abnormality associated with osteosarcoma.

Question 1055

Topic: 10. Pathology and Oncology
A 16-year-old female is diagnosed with conventional osteosarcoma of the distal femur. Staging CT scan of the chest reveals multiple bilateral pulmonary nodules. What is the most appropriate initial management approach?
. Immediate surgical resection of the primary tumor
. Palliative radiation therapy to the primary tumor
. Systemic neoadjuvant chemotherapy followed by surgical intervention
. Direct surgical resection of the lung metastases
. Observation with serial imaging

Correct Answer & Explanation

. Systemic neoadjuvant chemotherapy followed by surgical intervention

Explanation

Osteosarcoma is a systemic disease, and even without overt metastases, micrometastatic disease is often present at diagnosis. Neoadjuvant (pre-operative) chemotherapy is the cornerstone of treatment for conventional osteosarcoma, regardless of metastatic status.

Question 1056

Topic: 10. Pathology and Oncology

During pre-operative planning for a distal femoral osteosarcoma, MRI reveals a 'skip lesion' in the proximal femur, discontinuous from the primary tumor. What is the significance of this finding?

. It represents a benign reactive process and can be ignored.
. It indicates extensive marrow involvement requiring a wider resection margin proximally.
. It suggests synchronous multicentric osteosarcoma, necessitating different treatment protocols.
. It is a contraindication to limb salvage surgery, mandating amputation.
. It is a common artifact on MRI and does not affect surgical planning.

Correct Answer & Explanation

. It indicates extensive marrow involvement requiring a wider resection margin proximally.

Explanation

Correct Answer: BA 'skip lesion' in osteosarcoma refers to a separate focus of tumor in the same bone or a contiguous bone marrow space, distinct from the main lesion but originating from the same primary tumor. It represents true intraosseous metastasis. This finding necessitates a significantly wider proximal resection margin to ensure complete removal of all tumor, as inadequate margins carry a high risk of local recurrence. While it complicates limb salvage, it is not an absolute contraindication if adequate margins can still be achieved. It's not a benign process or an artifact, and while synchronous multicentric osteosarcoma exists, a skip lesion is generally considered a metastatic focus from the primary, requiring aggressive local control rather than a 'different protocol' beyond wider excision.

Question 1057

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with pain and swelling around the knee. Imaging suggests osteosarcoma. A biopsy is planned. Which of the following is the most crucial consideration for the biopsy approach?

. Performing the biopsy through the most superficial aspect of the tumor to minimize dissection.
. Ensuring the biopsy incision is longitudinal and directly in line with the planned definitive surgical incision.
. Using a transverse incision to allow for better wound closure.
. Aspiration of the lesion as the primary diagnostic step, avoiding an open biopsy.
. Biopsy should be performed by the most junior resident for training purposes.

Correct Answer & Explanation

. Ensuring the biopsy incision is longitudinal and directly in line with the planned definitive surgical incision.

Explanation

Correct Answer: BThe most crucial consideration for a biopsy of a suspected bone tumor, especially osteosarcoma, is to plan the biopsy tract so that it can be completely excised en bloc with the definitive tumor resection. This means the incision must be longitudinal and directly in line with the planned surgical approach for tumor removal. A contaminated biopsy tract left behind can lead to local recurrence. Performing it through the most superficial aspect is incorrect as it may lead to contamination of uninvolved tissues. A transverse incision is contraindicated if it crosses the planned limb salvage incision. Aspiration is usually insufficient for definitive diagnosis of osteosarcoma, which requires tissue for histopathology and grading. The biopsy should be performed by an experienced surgeon, ideally the one who will perform the definitive resection.

Question 1058

Topic: 10. Pathology and Oncology

Which imaging modality is considered the gold standard for defining the intramedullary extent of osteosarcoma and evaluating neurovascular involvement for pre-operative planning?

. Plain radiographs
. Computed Tomography (CT)
. Bone scintigraphy (Bone Scan)
. Magnetic Resonance Imaging (MRI)
. Positron Emission Tomography (PET)

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI)

Explanation

Correct Answer: DMagnetic Resonance Imaging (MRI) is the gold standard for local staging of osteosarcoma. It excels in delineating the intramedullary extent of the tumor, identifying skip lesions, assessing soft tissue involvement, and evaluating the relationship of the tumor to critical neurovascular structures. Plain radiographs give an initial overview but are poor for soft tissue or marrow extent. CT is superior for cortical bone detail and pulmonary metastases. Bone scintigraphy is useful for detecting multifocal disease or distant bone metastases. PET can identify metabolically active lesions and metastases but is not the primary modality for local surgical planning of intramedullary extent.

Question 1059

Topic: 10. Pathology and Oncology

What is the primary goal of neoadjuvant chemotherapy in the treatment of osteosarcoma?

. To eradicate all metastatic disease before surgery.
. To achieve complete tumor necrosis in the primary lesion.
. To reduce the risk of pathological fracture during surgery.
. To provide a window to assess tumor response and treat micrometastatic disease.
. To avoid the need for surgical resection altogether.

Correct Answer & Explanation

. To provide a window to assess tumor response and treat micrometastatic disease.

Explanation

Correct Answer: DThe primary goal of neoadjuvant chemotherapy for osteosarcoma is multi-faceted, but critically, it aims to treat subclinical micrometastatic disease, reduce the tumor volume (making surgery easier and potentially allowing limb salvage), and, importantly, assess the tumor's response to chemotherapy via histological evaluation of the resected specimen (chemoncrosis rate). A good response (e.g., >90% necrosis) is a favorable prognostic factor. While it helps reduce tumor size, achieving 'complete tumor necrosis' in the primary lesion is rare, and it rarely 'eradicate(s) all metastatic disease' though it treats micrometastases. It doesn't necessarily 'reduce the risk of pathological fracture during surgery' (it might actually increase if the tumor is highly lytic and weakened). It never avoids the need for surgical resection in standard care.

Question 1060

Topic: 10. Pathology and Oncology

After surgical resection of a high-grade osteosarcoma, what is the most common site for distant metastasis?

. Liver
. Brain
. Regional lymph nodes
. Bone marrow
. Lungs

Correct Answer & Explanation

. Lungs

Explanation

Correct Answer: EThe lungs are by far the most common site of distant metastasis for osteosarcoma, occurring in over 80-90% of patients with metastatic disease. This is why a CT scan of the chest is an essential part of the staging workup and surveillance protocol. Bone metastases are the second most common, followed by less frequent sites like brain, liver, or regional lymph nodes (lymph node metastasis is rare in osteosarcoma).

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