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10. Pathology and Oncology MCQs

Practice Set 14 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 261

Topic: 10. Pathology and Oncology

A 10-year-old asymptomatic girl is incidentally found to have a 2 cm eccentrically located, sharply demarcated radiolucent lesion with a sclerotic margin in the distal femoral metaphysis. What is the most appropriate management?

. Curettage and bone grafting
. Prophylactic internal fixation
. Core needle biopsy
. Observation
. Wide surgical resection

Correct Answer & Explanation

. Observation

Explanation

Nonossifying fibromas (NOF) are common benign, asymptomatic lesions that typically regress spontaneously. Observation is the standard of care for small, asymptomatic lesions.

Question 262

Topic: 10. Pathology and Oncology

An 11-year-old girl presents with a rapidly expanding, painful lesion in her distal tibia. Biopsy reveals blood-filled spaces separated by septa lacking endothelial lining. Which genetic translocation is most commonly associated with this primary lesion?

. t(11;22)
. t(9;22)
. t(16;17)
. USP6 (17p13) rearrangement
. t(X;18)

Correct Answer & Explanation

. USP6 (17p13) rearrangement

Explanation

Aneurysmal bone cysts (ABCs) are characterized by blood-filled cystic spaces and are primarily associated with USP6 gene rearrangements on chromosome 17p13.

Question 263

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a painful mass in the distal femur. Radiographs reveal a sunburst periosteal reaction and Codman's triangle. Which of the following is the most significant prognostic factor for survival?

. Tumor volume
. Alkaline phosphatase levels
. Response to neoadjuvant chemotherapy
. Specific histologic subtype
. Presence of skip lesions

Correct Answer & Explanation

. Response to neoadjuvant chemotherapy

Explanation

The percentage of tumor necrosis following neoadjuvant chemotherapy is the most critical prognostic indicator for long-term survival in osteosarcoma.

Question 264

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with fever, elevated ESR, and a diaphyseal lytic lesion in the femur with an "onion-skin" periosteal reaction. Histology shows small blue round cells. What is the pathognomonic chromosomal translocation?

. t(11;22)
. t(9;22)
. t(2;13)
. t(X;18)
. t(12;16)

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. It often mimics osteomyelitis clinically.

Question 265

Topic: 10. Pathology and Oncology

A 14-year-old boy complains of chronic knee pain. Radiographs reveal a 2 cm eccentric, radiolucent lesion in the proximal tibial epiphysis with a thin sclerotic rim. Histology shows "chicken-wire" calcification. What is the diagnosis?

. Giant cell tumor
. Clear cell chondrosarcoma
. Chondroblastoma
. Chondromyxoid fibroma
. Enchondroma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a benign cartilage-forming tumor that characteristically arises in the epiphysis of long bones in growing children. "Chicken-wire" calcification is a classic histologic hallmark.

Question 266

Topic: Bone Tumors
A 10-year-old girl is evaluated for a limp. Radiographs demonstrate a "shepherd's crook" deformity of the proximal femur with a ground-glass appearance of the medullary canal. She also exhibits precocious puberty and irregular café-au-lait spots. What is the most likely diagnosis?
. Neurofibromatosis type 1
. McCune-Albright syndrome
. Jaffe-Campanacci syndrome
. Ollier disease
. Maffucci syndrome

Correct Answer & Explanation

. McCune-Albright syndrome

Explanation

McCune-Albright syndrome is a triad of polyostotic fibrous dysplasia (causing the ground-glass bone lesions and shepherd's crook deformity), café-au-lait spots with irregular "coast of Maine" borders, and endocrinopathies such as precocious puberty.

Question 267

Topic: 10. Pathology and Oncology

An 11-year-old boy presents with localized thigh pain and a low-grade fever. Radiographs reveal a permeative, destructive diaphyseal lesion in the femur with a multilamellated ("onion skin") periosteal reaction. Biopsy shows sheets of small, round, blue cells. Which chromosomal translocation is characteristically associated with this tumor?

. t(9;22)
. t(11;22)
. t(12;16)
. t(X;18)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The t(11;22) translocation is found in approximately 85% of Ewing sarcoma cases, leading to the creation of the EWS-FLI1 fusion protein.

Question 268

Topic: 10. Pathology and Oncology

An 11-year-old boy has multiple, hard, tender nodules in his posterior shoulder girdle and paraspinous muscles. He also has a shortened first metatarsal with a delta-shaped first proximal phalanx. The diagnosis is:

. Dysplasia epiphysialis hemimelica
. Multiple exostoses
. Fibrodysplasia ossificans progressiva
. Myositis ossificans
. Metastatic osteosarcoma

Correct Answer & Explanation

. Fibrodysplasia ossificans progressiva

Explanation

Fibrodysplasia ossificans progressiva is a disorder of the BMP4 signaling pathway. This condition is characterized by multiple osseous masses occurring in muscle, especially in the dorsal and axial regions. There is also a characteristic dysmorphology of the great toe, consisting of a shortened first metatarsal, delta-shaped phalanx, and some valgus.

Question 269

Topic: Bone Tumors

Klippel-Trenaunay syndrome is characterized by cutaneous capillary venous malformation, varicose veins, and which of the following:

. Multiple enchondromas
. Multiple osteochondromas
. Limb hypertrophy
. Seizure disorder
. C ongenital pseudarthrosis of the tibia

Correct Answer & Explanation

. Limb hypertrophy

Explanation

Klippel-Trenaunay syndrome has three essential features: cutaneous capillary venous malformation, varicose veins, and hypertrophy of the involved limb in length and/or width. The syndrome usually presents before adolescence. The tissue abnormalities typically do not cross the midline, and the entire limb is not uniformly affected.

Question 270

Topic: 10. Pathology and Oncology
Which of the following is related to the etiology of Ewing's sarcoma?
. Chromosomal translocation (11/22)
. Viral infection
. Bacterial infection
. Trauma
. Single base mutation

Correct Answer & Explanation

. Chromosomal translocation (11/22)

Explanation

Ewing's sarcoma belongs to the family of round cell sarcomas. A translocation t(11;22)(q24;q12) has been discovered in Ewing's sarcoma. This translocation results in a novel protein, EWS-FLI1, that causes rapid growth of cells arising from the neural crest.

Question 271

Topic: 10. Pathology and Oncology

A 5-year-old girl is brought to your office because of a mass in the back of her right knee. The family has noticed the mass for the past 8 months, and they also tell you that it varies in size with activity. The mass is painless and is located on the medial side of the popliteal fossa. It measures 2 cm to 4 cm and is discrete, firm, and nontender. Examinations of her knee and gait are unremarkable otherwise. You recommend:

. Observation with return if any changes
. Magnetic resonance imaging
. Aspiration
. Excisional biopsy
. Knee arthroscopy to look for intra-articular causes

Correct Answer & Explanation

. Observation with return if any changes

Explanation

The patient history and physical examination are consistent with a benign popliteal cyst. This type of cyst is usually unassociated with any intra- articular pathology in children. The cyst resolves on its own with time. Further study or biopsy would be indicated only if the mass were progressively enlarging, tender, or located in an atypical area.

Question 272

Topic: 10. Pathology and Oncology
In children with Ewing's sarcoma, the risk of local recurrence at the tumor site after treatment is greatest in which region:
. Midshaft femur
. Proximal fibula
. Pelvis
. Distal femur
. Proximal humerus

Correct Answer & Explanation

. Pelvis

Explanation

The risk of local recurrence is greatest for Ewing's sarcomas arising in the pelvis. The prognosis is poor. Many centers attempt resection of the pelvis if there is a good response to chemotherapy.

Question 273

Topic: 10. Pathology and Oncology

The protein neurofibromin normally acts in which of the following ways:

. Inhibits fibroblast growth factor
. Promotes proteoglycan assembly
. Downregulates Ras protein
. C auses nerve cells to divide
. Promotes tumor formation

Correct Answer & Explanation

. Downregulates Ras protein

Explanation

If defective, neurofibromin is the protein that causes neurofibromatosis. Neurofibroma is coded on chromosome 17, and it acts as a tumor suppressor by downregulating Ras protein, which enhances cell growth and proliferation.

Question 274

Topic: 10. Pathology and Oncology

Which of the following chromosomal translocations is most commonly associated with Ewing's sarcoma?

. t(11;22)
. t(9;22)
. t(X;18)
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing's sarcoma is most commonly associated with the t(11;22) translocation, which results in the EWS-FLI1 fusion protein. Other classic translocations include t(X;18) for synovial sarcoma and t(9;22) for extraskeletal myxoid chondrosarcoma.

Question 275

Topic: Bone Tumors

A 65-year-old male presents with bone pain and a lytic lesion in his proximal femur. Laboratory studies reveal hypercalcemia and a monoclonal spike on serum protein electrophoresis. Which imaging modality is most appropriate to evaluate the extent of skeletal involvement?

. Technetium-99m bone scan
. Low-dose whole-body CT
. MRI of the affected femur only
. Indium-111 leukocyte scan
. Dexa scan

Correct Answer & Explanation

. Low-dose whole-body CT

Explanation

Low-dose whole-body CT or whole-body MRI are the preferred imaging modalities for assessing skeletal involvement in multiple myeloma. Technetium-99m bone scans are notoriously unreliable because myeloma lesions typically lack osteoblastic activity.

Question 276

Topic: 10. Pathology and Oncology
In the treatment of extremity osteosarcoma, what percentage of tumor necrosis following neoadjuvant chemotherapy is defined as a "good response" and correlates with improved long-term survival?
. Greater than 50%
. Greater than 75%
. Greater than 90%
. Greater than 95%
. 100%

Correct Answer & Explanation

. Greater than 90%

Explanation

A "good response" to neoadjuvant chemotherapy in osteosarcoma is defined as greater than 90% tumor necrosis (Huvos grade III or IV). This is a strong independent prognostic factor for long-term survival.

Question 277

Topic: 10. Pathology and Oncology

In a patient diagnosed with high-grade osteosarcoma of the distal femur, what is the most important prognostic factor for long-term survival?

. Tumor volume at presentation
. Histologic response to neoadjuvant chemotherapy
. Alkaline phosphatase level
. Anatomic location of the tumor
. Patient age

Correct Answer & Explanation

. Histologic response to neoadjuvant chemotherapy

Explanation

The histologic response to neoadjuvant chemotherapy (percentage of tumor necrosis) is the most critical prognostic factor in high-grade osteosarcoma. Greater than 90% necrosis indicates a favorable prognosis.

Question 278

Topic: 10. Pathology and Oncology

A soft tissue mass is biopsied from the foot of a 25-year-old male. Histology shows a biphasic pattern of epithelial and spindle cells. Which of the following chromosomal translocations is characteristic of this tumor?

. t(11;22)
. t(X;18)
. t(2;13)
. t(12;16)
. t(9;22)

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, leading to the SYT-SSX fusion gene. It commonly presents in the extremities of young adults and can exhibit biphasic or monophasic histology.

Question 279

Topic: 10. Pathology and Oncology

Which of the following clinical or radiographic features is most suggestive of malignant transformation of an enchondroma into a secondary chondrosarcoma?

. Presence of stippled calcifications
. Location in the small bones of the hand
. Endosteal scalloping greater than two-thirds of the cortical thickness
. Size less than 3 cm
. Asymptomatic lesion discovered incidentally

Correct Answer & Explanation

. Endosteal scalloping greater than two-thirds of the cortical thickness

Explanation

Deep endosteal scalloping (greater than two-thirds of the cortical thickness), cortical breakthrough, and new-onset pain are strong indicators of malignant transformation to chondrosarcoma. Lesions in the hand are typically benign despite active histologic appearance.

Question 280

Topic: 10. Pathology and Oncology

A 30-year-old female presents with a slowly enlarging mass on the posterior aspect of her distal thigh. Radiographs reveal a heavily ossified, lobulated mass attached to the posterior cortex of the distal femur. What is the characteristic genetic mutation associated with this lesion?

. p53 deletion
. Rb1 mutation
. MDM2/CDK4 amplification
. EXT1 mutation
. GNAS mutation

Correct Answer & Explanation

. MDM2/CDK4 amplification

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma classically located on the posterior distal femur. It is driven by ring chromosomes leading to amplification of the MDM2 and CDK4 genes.

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