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10. Pathology and Oncology MCQs

Practice Set 334 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 6661

Topic: 10. Pathology and Oncology

A 14-year-old boy with conventional osteosarcoma of the distal femur completes neoadjuvant chemotherapy. Restaging scans show two new 1 cm peripheral lung nodules. His primary tumor is resectable. What is the most appropriate management?

. Palliative radiation to the primary tumor and lungs
. Wide resection of the primary tumor followed by bilateral thoracotomies for metastasectomy
. Switch to second-line chemotherapy and abandon surgical resection
. Amputation followed by whole-lung irradiation
. Hospice care as the disease is now terminal

Correct Answer & Explanation

. Wide resection of the primary tumor followed by bilateral thoracotomies for metastasectomy

Explanation

Pulmonary metastases in osteosarcoma do not preclude curative-intent surgery. Wide resection of the primary bone tumor and complete resection of pulmonary metastases offer the best chance for long-term survival.

Question 6662

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a solitary enchondroma of the distal femur discovered incidentally on an MRI for a knee sprain. Which of the following statements regarding solitary enchondromas is true?

. They have a high risk of malignant transformation (20-30%).
. They typically require immediate prophylactic curettage.
. They are associated with EXT1 and EXT2 mutations.
. They frequently harbor somatic mutations in the IDH1 or IDH2 genes.
. They present with severe, unrelenting night pain.

Correct Answer & Explanation

. They frequently harbor somatic mutations in the IDH1 or IDH2 genes.

Explanation

Solitary enchondromas are common benign cartilaginous tumors that often harbor somatic mutations in IDH1 or IDH2. They are typically asymptomatic and carry a very low risk of malignant transformation (<1%).

Question 6663

Topic: 10. Pathology and Oncology

In a patient with Ewing sarcoma, what is the most common site of metastasis at the time of initial presentation?

. Liver
. Brain
. Lungs
. Lymph nodes
. Spine

Correct Answer & Explanation

. Lungs

Explanation

The lungs are the most common site of metastasis for Ewing sarcoma at initial presentation. Bone and bone marrow are the next most common sites.

Question 6664

Topic: 10. Pathology and Oncology

A 45-year-old man undergoes resection of a large pelvic mass. Histopathology reveals a biphasic tumor with islands of well-differentiated, low-grade hyaline cartilage adjacent to a high-grade, non-cartilaginous spindle cell sarcoma. What is the diagnosis?

. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Clear cell chondrosarcoma
. Osteosarcoma
. Chondroblastic osteosarcoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a biphasic histologic pattern with a sharp demarcation between a low-grade cartilage tumor and a high-grade spindle cell component. It carries a very poor prognosis.

Question 6665

Topic: 10. Pathology and Oncology

A 22-year-old male with Ollier disease presents with worsening pain and a rapidly enlarging mass in his proximal tibia. Which of the following is the most likely secondary malignancy to develop in this patient?

. Secondary osteosarcoma
. Secondary chondrosarcoma
. Ewing sarcoma
. Malignant peripheral nerve sheath tumor
. Giant cell tumor of bone

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Patients with Ollier disease (multiple enchondromatosis) have an elevated risk (approximately 25-30%) of malignant transformation. This transformation is most commonly to a secondary chondrosarcoma.

Question 6666

Topic: 10. Pathology and Oncology

An MRI of a patient with distal femoral osteosarcoma reveals a distinct, separate tumor focus within the proximal medullary canal of the same bone. What term best describes this finding, and how does it affect surgical planning?

. Skip metastasis; requires an intra-articular resection
. Skip metastasis; necessitates extending the surgical resection margin or whole-bone resection
. Lung metastasis; indicates the need for metastasectomy
. Local recurrence; mandates amputation
. Chondromatous dedifferentiation; no change in surgical plan

Correct Answer & Explanation

. Skip metastasis; necessitates extending the surgical resection margin or whole-bone resection

Explanation

A skip metastasis is a separate focus of tumor within the same bone or transarticular. Its presence dictates a broader resection, often requiring whole-bone resection or a significantly higher amputation level to achieve negative margins.

Question 6667

Topic: Bone Tumors
A 19-year-old female presents with a small (< 2 cm), painless cartilaginous lesion on the surface of the proximal humerus cortex. Histologically, it shows hypercellularity and binucleate cells. What clinical or radiographic feature distinguishes this periosteal chondroma from a periosteal chondrosarcoma?
. Presence of binucleate cells
. Cortical saucerization
. Size of the lesion and lack of soft tissue mass invasion
. Presence of cartilaginous matrix
. Sclerotic periosteal reaction

Correct Answer & Explanation

. Size of the lesion and lack of soft tissue mass invasion

Explanation

Periosteal chondromas often exhibit hypercellularity and atypia mimicking malignancy. They are distinguished from periosteal chondrosarcomas primarily by their small size (< 3 cm) and lack of soft tissue invasion.

Question 6668

Topic: 10. Pathology and Oncology

Which of the following characteristics is most suggestive of clear cell chondrosarcoma?

. Diaphyseal location in children
. Epiphyseal location in adults
. Multiple fluid-fluid levels on MRI
. Onion-skin periosteal reaction
. Biphasic histology with spindle cells

Correct Answer & Explanation

. Epiphyseal location in adults

Explanation

Clear cell chondrosarcoma is a low-grade malignant cartilage tumor that characteristically arises in the epiphysis of long bones in adults. Because of its epiphyseal location, it can sometimes radiographically mimic a chondroblastoma.

Question 6669

Topic: 10. Pathology and Oncology

A 60-year-old man presents with a painful lesion in the diaphysis of the femur. Biopsy reveals small blue round cells mixed with islands of benign-appearing cartilage and a hemangiopericytoma-like vascular pattern (staghorn vessels). What is the most likely diagnosis?

. Ewing sarcoma
. Dedifferentiated chondrosarcoma
. Mesenchymal chondrosarcoma
. Chondroblastic osteosarcoma
. Lymphoma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Mesenchymal chondrosarcoma is a rare, aggressive tumor characterized histologically by a bimorphic pattern of highly cellular small round blue cells and islands of well-differentiated hyaline cartilage with branching staghorn vessels.

Question 6670

Topic: 10. Pathology and Oncology

A 55-year-old woman is incidentally found to have a 3 cm enchondroma in her proximal humerus. Radiographs show classic rings and arcs calcification. She is completely asymptomatic. What is the most appropriate management?

. Wide local excision
. Intralesional curettage with phenol adjuvant
. Serial observation with radiographs
. Prophylactic internal fixation
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Serial observation with radiographs

Explanation

Asymptomatic enchondromas discovered incidentally in adults without aggressive radiographic features should be managed with serial observation. This monitors for any pain or radiographic changes suggesting malignant transformation.

Question 6671

Topic: 10. Pathology and Oncology

Regarding survival in patients with osteosarcoma who develop pulmonary metastases, which factor is most strongly associated with improved long-term outcomes?

. Use of targeted radiation to lung nodules
. Complete surgical resection of all pulmonary nodules
. Substituting methotrexate with immunotherapy
. The presence of a malignant pleural effusion
. Bilateral rather than unilateral lung involvement

Correct Answer & Explanation

. Complete surgical resection of all pulmonary nodules

Explanation

The most significant prognostic factor for long-term survival in osteosarcoma patients with pulmonary metastases is the ability to achieve complete surgical resection of all metastatic lung lesions (metastasectomy).

Question 6672

Topic: 10. Pathology and Oncology

A 30-year-old male has an expansile lucent lesion in the proximal phalanx of the index finger.

A biopsy confirms enchondroma. During surgical treatment, what is the most important intraoperative step to minimize the risk of local recurrence?

. En bloc resection of the phalanx
. Application of liquid nitrogen
. Thorough mechanical burring of the cavity walls
. Intraoperative radiation therapy
. Amputation of the digit

Correct Answer & Explanation

. Thorough mechanical burring of the cavity walls

Explanation

In the treatment of enchondromas of the hand, thorough intralesional curettage supplemented with high-speed mechanical burring of the cavity walls is critical to remove microscopic tumor extensions and minimize local recurrence.

Question 6673

Topic: 10. Pathology and Oncology

What is the primary role of whole-lung irradiation in the treatment of Ewing sarcoma?

. Primary treatment for localized pelvic tumors
. Prophylaxis for high-risk patients with localized disease
. Treatment of patients presenting with pulmonary metastases
. Palliative care for completely chemo-resistant disease
. It has no role and is contraindicated due to toxicity

Correct Answer & Explanation

. Treatment of patients presenting with pulmonary metastases

Explanation

Whole-lung irradiation is often incorporated into the treatment protocol for patients with Ewing sarcoma who present with pulmonary metastases. It has been shown to improve event-free and overall survival in this metastatic cohort.

Question 6674

Topic: Bone Tumors

A 24-year-old male presents with a mildly painful palpable mass on the proximal humerus. Radiographs reveal a surface lesion with cortical saucerization and a sclerotic periosteal reaction at the proximal and distal margins.

What is the most likely diagnosis?

. Periosteal osteosarcoma
. Parosteal osteosarcoma
. Periosteal chondroma
. Osteochondroma
. Myositis ossificans

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas typically present in young adults as surface lesions causing saucerization of the underlying cortex with a sclerotic margin. They are usually less than 3 cm in size and lack medullary involvement.

Question 6675

Topic: 10. Pathology and Oncology

In a 15-year-old male diagnosed with high-grade intramedullary osteosarcoma of the distal femur, what is the most significant prognostic factor for overall survival at the time of presentation?

. Tumor volume > 100 mL
. Presence of pulmonary metastases
. Alkaline phosphatase level
. Percentage of tumor necrosis after chemotherapy
. Histologic subtype

Correct Answer & Explanation

. Presence of pulmonary metastases

Explanation

The presence of macroscopic pulmonary metastases at presentation is the most critical adverse prognostic factor for overall survival in osteosarcoma. Tumor necrosis following neoadjuvant chemotherapy is the best predictor of event-free survival post-treatment.

Question 6676

Topic: 10. Pathology and Oncology

A 45-year-old patient with a known distal femur enchondroma presents with new-onset, deep, dull aching pain at night. Radiographs show increased endosteal scalloping.

Which radiographic feature is most indicative of malignant transformation to a low-grade chondrosarcoma?

. Popcorn calcification matrix
. Endosteal scalloping of > 2/3 cortical thickness
. Intralesional radiolucency
. Well-defined sclerotic margins
. Absence of a soft tissue mass

Correct Answer & Explanation

. Endosteal scalloping of > 2/3 cortical thickness

Explanation

Malignant transformation of an enchondroma to a low-grade chondrosarcoma is suggested by deep endosteal scalloping involving more than 2/3 of the cortical thickness, new-onset pain, or cortical breakthrough. Popcorn calcifications are a feature of cartilaginous tumors generally, not specific for malignancy.

Question 6677

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a growing, tender mass on her anterior tibia. Biopsy confirms a periosteal chondroma. The lesion measures 2.5 cm. What is the recommended treatment?

. Neoadjuvant chemotherapy followed by wide resection
. Radiotherapy
. Intralesional curettage
. Marginal excision including the underlying sclerotic cortex
. Observation only

Correct Answer & Explanation

. Marginal excision including the underlying sclerotic cortex

Explanation

For a symptomatic or growing periosteal chondroma, the recommended treatment is marginal excision, removing the tumor along with its underlying sclerotic bony base. This ensures a low risk of local recurrence.

Question 6678

Topic: 10. Pathology and Oncology

A 17-year-old male with a history of distal femur osteosarcoma, treated with wide resection and chemotherapy two years ago, presents with a solitary 1.5 cm pulmonary metastasis. The primary site has no local recurrence. What is the most appropriate management?

. Palliative radiation therapy to the lung
. Hospice care
. Surgical resection of the pulmonary metastasis
. High-dose isolated lung perfusion
. Switching to second-line oral tyrosine kinase inhibitors

Correct Answer & Explanation

. Surgical resection of the pulmonary metastasis

Explanation

Surgical resection (metastasectomy) of pulmonary metastases in osteosarcoma provides a significant survival benefit when the primary tumor is controlled and the lung lesions are completely resectable. It is the standard of care for isolated, resectable pulmonary relapses.

Question 6679

Topic: 10. Pathology and Oncology

A 40-year-old male complains of chronic hip pain. Radiographs reveal an epiphyseal lytic lesion in the proximal femur with a sclerotic margin and central calcifications. What is the most likely diagnosis, considering this distinct epiphyseal location in an adult?

. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor
. Osteosarcoma
. Ewing sarcoma

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma typically presents as a lytic epiphyseal lesion in adults (30-50 years old), often mimicking a chondroblastoma, which typically occurs in skeletally immature patients. It requires wide surgical resection due to its low-grade malignant potential.

Question 6680

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with multiple cartilaginous lesions in the hands and long bones, accompanied by distinct soft-tissue masses with phleboliths noted on radiographs. What is the most significant long-term risk associated with his underlying syndrome?

. Pathologic fracture requiring amputation
. Malignant transformation to chondrosarcoma approaching 100%
. Development of acute myeloid leukemia
. Progression to multiple myeloma
. Spontaneous resolution of the lesions by skeletal maturity

Correct Answer & Explanation

. Malignant transformation to chondrosarcoma approaching 100%

Explanation

The patient has Maffucci syndrome, characterized by multiple enchondromas and soft-tissue hemangiomas. Unlike Ollier disease, patients with Maffucci syndrome have a near 100% risk of malignant transformation, most commonly to chondrosarcoma or visceral malignancies.

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