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10. Pathology and Oncology MCQs

Practice Set 233 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 4641

Topic: 10. Pathology and Oncology

A 28-year-old elite marathon runner undergoes a vastus lateralis muscle biopsy. The predominant muscle fibers identified are characterized by high mitochondrial density, dense capillary networks, and high myoglobin content. Which of the following best describes the primary energy pathway and predominant myosin heavy chain (MHC) isoform of these fibers?

. Glycolytic metabolism, MHC IIx
. Oxidative metabolism, MHC IIa
. Oxidative metabolism, MHC I
. Glycolytic metabolism, MHC I
. Anaerobic metabolism, MHC IIb

Correct Answer & Explanation

. Glycolytic metabolism, MHC IIx

Explanation

The biopsy describes Type I (slow-twitch) muscle fibers, which are highly fatigue-resistant and utilized extensively by endurance athletes. Type I fibers rely on oxidative (aerobic) metabolism, have high mitochondrial and capillary density, and express the MHC I isoform.

Question 4642

Topic: 10. Pathology and Oncology

An elite marathon runner undergoes a muscle biopsy of the gastrocnemius. The predominant muscle fibers identified are rich in mitochondria, myoglobin, and rely on oxidative metabolism. Which of the following best characterizes the mechanical properties of these specific fibers compared to the other major fiber type?

. Faster contraction speed and rapid fatigue
. Slower contraction speed and rapid fatigue
. Faster contraction speed and high resistance to fatigue
. Slower contraction speed and high resistance to fatigue
. High force generation utilizing predominantly glycolytic pathways

Correct Answer & Explanation

. Faster contraction speed and rapid fatigue

Explanation

The biopsy describes Type I muscle fibers (slow-twitch, red fibers). They are highly oxidative, rich in mitochondria and myoglobin, and are characterized by a slow contraction speed but a high resistance to fatigue, making them ideal for endurance activities.

Question 4643

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a deep, slow-growing soft tissue mass in his thigh. Core needle biopsy demonstrates a biphasic pattern of epithelial-like cells and spindle cells. Molecular analysis reveals a t(X;18)(p11;q11) translocation. What fusion gene is created by this specific chromosomal abnormality?

. EWS-FLI1
. SYT-SSX
. FUS-CHOP
. PAX3-FOXO1
. MYC-IGH

Correct Answer & Explanation

. EWS-FLI1

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which fuses the SYT gene on chromosome 18 with one of the SSX genes (usually SSX1 or SSX2) on the X chromosome. EWS-FLI1 is characteristic of Ewing sarcoma t(11;22); FUS-CHOP is seen in myxoid liposarcoma t(12;16).

Question 4644

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an "onion skin" periosteal reaction. Biopsy reveals small, round blue cells. Which chromosomal translocation is most characteristic of this malignancy?

. t(11;22)(q24;q12)
. t(9;22)(q34;q11)
. t(X;18)(p11;q11)
. t(2;13)(q35;q14)
. t(12;16)(q13;p11)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. Synovial sarcoma exhibits t(X;18), and alveolar rhabdomyosarcoma shows t(2;13).

Question 4645

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, destructive diaphyseal lesion in his femur with an associated soft tissue mass. Biopsy reveals uniform small round blue cells. Molecular testing of the tumor tissue is most likely to reveal which of the following chromosomal translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and histologic picture describes Ewing sarcoma. The hallmark genetic abnormality in the vast majority of Ewing sarcoma cases is the t(11;22) chromosomal translocation, resulting in the EWS-FLI1 fusion protein.

Question 4646

Topic: 10. Pathology and Oncology

Ewing sarcoma is a highly aggressive bone tumor that typically affects children and adolescents. The majority of these tumors are characterized by a specific chromosomal translocation that results in the oncogenic EWS-FLI1 fusion protein. Which of the following is the correct translocation?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is genetically characterized by a balanced chromosomal translocation t(11;22)(q24;q12) in approximately 85% of cases. This translocation fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, creating a chimeric EWS-FLI1 transcription factor that serves as the primary driver of oncogenesis.

Question 4647

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with calf pseudohypertrophy, frequent falls, and a positive Gowers sign. Muscle biopsy confirms a genetic muscular dystrophy. The defective protein in this condition normally functions to link which of the following structures?

. Actin filaments to the extracellular matrix
. Myosin heads to actin filaments
. Sarcoplasmic reticulum to the T-tubules
. Z-disks of adjacent sarcomeres
. Tropomyosin to troponin

Correct Answer & Explanation

. Actin filaments to the extracellular matrix

Explanation

Duchenne Muscular Dystrophy is caused by an absence of dystrophin. Dystrophin is a cytoskeletal protein that structurally links the intracellular actin cytoskeleton to the extracellular matrix via the dystrophin-associated glycoprotein complex, stabilizing the sarcolemma.

Question 4648

Topic: 10. Pathology and Oncology

A 14-year-old boy has a permeative diaphyseal lesion of the femur. Biopsy reveals small round blue cells. Cytogenetic analysis is most likely to show which of the following translocations?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Ewing sarcoma is classically associated with the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, and t(9;22) is seen in extraskeletal myxoid chondrosarcoma.

Question 4649

Topic: 10. Pathology and Oncology

A 15-year-old male presents with a deep, slow-growing soft tissue mass in his thigh. Histological biopsy demonstrates a biphasic tumor consisting of spindle cells and glandular epithelial elements. Cytogenetic analysis reveals a t(X;18) chromosomal translocation. What is the diagnosis?

. Ewing sarcoma
. Synovial sarcoma
. Alveolar rhabdomyosarcoma
. Clear cell sarcoma
. Myxoid liposarcoma

Correct Answer & Explanation

. Ewing sarcoma

Explanation

The t(X;18)(p11;q11) translocation is pathognomonic for synovial sarcoma, resulting in the SYT-SSX fusion gene. Despite its name, the tumor arises from mesenchymal cells, not true synovium, and classically exhibits a biphasic histology.

Question 4650

Topic: 10. Pathology and Oncology

A biopsy of a destructive metaphyseal lesion in a 14-year-old boy reveals sheets of uniform, small round blue cells. Cytogenetic analysis is most likely to show which of the following translocations?

. t(X;18)(p11;q11)
. t(11;22)(q24;q12)
. t(2;13)(q35;q14)
. t(12;16)(q13;p11)
. t(9;22)(q22;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

The clinical and histologic description represents Ewing sarcoma. The hallmark cytogenetic abnormality is t(11;22)(q24;q12), resulting in the EWSR1-FLI1 fusion protein, which is found in about 85% of cases. t(X;18) is seen in synovial sarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma. t(12;16) is seen in myxoid liposarcoma.

Question 4651

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a slow-growing soft tissue mass in the popliteal fossa. Histological examination reveals a biphasic pattern consisting of epithelial and spindle cells. Cytogenetic analysis of this tumor is most likely to reveal which of the following chromosomal translocations?

. t(11;22)(q24;q12)
. t(x;18)(p11;q11)
. t(12;16)(q13;p11)
. t(9;22)(q22;q12)
. t(2;13)(q35;q14)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The scenario describes a synovial sarcoma (biphasic histology in a young adult near a large joint). The pathognomonic translocation is t(x;18), resulting in the SYT-SSX fusion gene. t(11;22) is Ewing sarcoma; t(12;16) is myxoid liposarcoma; t(9;22) is extraskeletal myxoid chondrosarcoma; t(2;13) is alveolar rhabdomyosarcoma.

Question 4652

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive diaphyseal lesion in his femur with an associated soft tissue mass. Biopsy reveals small round blue cells. Molecular testing demonstrates a t(11;22)(q24;q12) chromosomal translocation. This specific genetic abnormality results in the fusion of which two genes?

. SYT and SSX1
. EWS and FLI1
. TLS and CHOP
. PAX3 and FKHR
. COL1A1 and PDGFB

Correct Answer & Explanation

. SYT and SSX1

Explanation

The t(11;22)(q24;q12) translocation is the hallmark of Ewing sarcoma, resulting in the EWS-FLI1 fusion protein. SYT-SSX is seen in synovial sarcoma t(X;18), TLS-CHOP in myxoid liposarcoma t(12;16), and PAX3-FKHR in alveolar rhabdomyosarcoma t(2;13).

Question 4653

Topic: 10. Pathology and Oncology
Which treatment regimen for Ewing sarcoma most effectively controls disease?
. Chemotherapy alone
. Chemotherapy plus wide surgical resection
. Chemotherapy plus radiation therapy
. Surgery plus radiation therapy

Correct Answer & Explanation

. Chemotherapy plus wide surgical resection

Explanation

Patients with Ewing sarcoma need chemotherapy to treat micrometastatic disease. Local control options include radiation therapy or wide surgical resection. More recent data support improved outcomes for patients who undergo wide surgical resection; consequently, chemotherapy plus wide surgical resection is the most effective regimen.

Question 4654

Topic: 10. Pathology and Oncology
A patient undergoes excision of a presumed lipoma of the superficial thigh. Final pathology reveals synovial sarcoma without reference to the margins. What is the recommendation for definitive treatment?
. Observation
. External beam radiation therapy alone
. Wide resection of the tumor bed and radiation therapy
. Radiation therapy and chemotherapy

Correct Answer & Explanation

. Wide resection of the tumor bed and radiation therapy

Explanation

An unplanned excision of a soft-tissue sarcoma occurs when a surgeon removes a soft-tissue mass while believing it is benign, and, upon pathologic examination, learns that it is malignant. These procedures often are performed without presurgical staging studies or appropriate oncologic surgical technique. Following an unplanned excision, patients usually are referred to a sarcoma center for definitive care. Definitive treatment is hindered by the lack of presurgical imaging, sophisticated pathologic examination findings, and a contaminated tumor bed larger than the original tumor. Further, as many as 50% of cases are associated with residual disease within the tumor bed, even when no tumor can be identified with imaging or an examination and the initial surgical report indicates all gross disease has been removed. Most patients for whom an inadequate excision of an unsuspected sarcoma is performed are treated with reexcision of the tumor bed, and, very often, adjuvant radiotherapy.

Question 4655

Topic: 10. Pathology and Oncology
A patient's upper extremity radiographs are shown. What is the most likely inheritance pattern of this condition?
. X-linked recessive
. X-linked dominant
. Autosomal recessive
. Autosomal dominant
. Sporadic

Correct Answer & Explanation

. Autosomal dominant

Explanation

This patient has multiple hereditary exostoses. Note the multiple sessile osteochondromas on the humerus and ulna. A characteristic bowing deformity of the forearm and pseudo-Madelung deformity of the wrist are also present. Multiple hereditary exostoses is autosomal dominant. The putative tumor suppressive gene mutation is EXT1 or EXT2. The risk of low-grade chondrosarcoma occurring is approximately 10%. In most patients, the forearm deformity does not cause a major problem and can be treated nonoperatively.

Question 4656

Topic: 10. Pathology and Oncology
A 13-year-old boy presents with a 5-month history of a left hip injury. He has no current pain, but substantial, progressive limitations in hip flexion are present. What is the most likely diagnosis?
. Extraskeletal osteosarcoma
. Myositis ossificans
. Chondrosarcoma
. Pelvic osteosarcoma

Correct Answer & Explanation

. Myositis ossificans

Explanation

This patient has a mineralized mass in the soft tissues in the rectus femoris origin. The clinical history favors an avulsion injury with subsequent myositis ossificans, and the imaging is consistent with an ossified soft-tissue mass. Extraskeletal osteosarcoma is a rare soft-tissue sarcoma and is generally seen in adults. Chondrosarcoma is also generally seen in adults and would have a more chondroid matrix as opposed to mature-looking bone on a CT scan. Pelvic osteosarcoma could have this appearance on radiograph, but the CT scan and MR image confirm this is a soft-tissue process with mature mineralization.

Question 4657

Topic: 10. Pathology and Oncology

A 52-year-old male undergoes a radiograph of his shoulder for chronic, dull pain. The x-ray reveals a destructive, intra-medullary lesion in the proximal humerus displaying "ring and arc" calcifications. CT scan reveals endosteal scalloping involving 80% of the cortical thickness. What is the most likely diagnosis?

. Osteosarcoma
. Ewing Sarcoma
. Multiple Myeloma
. Chondrosarcoma
. Simple Bone Cyst

Correct Answer & Explanation

. Osteosarcoma

Explanation

The radiographic presence of "ring and arc" or "popcorn" calcifications is the classic hallmark of a cartilaginous tumor matrix. In a patient over 40 years old, differentiating a benign enchondroma from a malignant chondrosarcoma can be difficult. However, pain at rest and imaging signs such as endosteal scalloping greater than 2/3 (66%) of the cortical thickness, cortical breakthrough, or an associated soft tissue mass are highly indicative of malignant transformation or a primary Chondrosarcoma.

Question 4658

Topic: 10. Pathology and Oncology



A 14-year-old boy presents with progressive distal thigh pain. Imaging shows a highly aggressive mixed lytic and sclerotic lesion in the distal femoral metaphysis with a 'sunburst' periosteal reaction. Biopsy reveals malignant cells producing osteoid matrix. Which of the following genetic alterations is most commonly associated with this tumor?

. t(11;22) chromosomal translocation
. Mutations in the RB1 and TP53 genes
. t(X;18) chromosomal translocation
. Amplification of the MDM2 gene
. Activating mutation in GNAS

Correct Answer & Explanation

. t(11;22) chromosomal translocation

Explanation

The clinical presentation and histology confirm osteosarcoma, which is characterized by malignant spindle cells producing osteoid. Osteosarcoma is frequently associated with mutations in critical tumor suppressor genes, primarily RB1 and TP53.

Question 4659

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a slowly enlarging, painful mass around his knee joint. An MRI demonstrates a soft tissue mass adjacent to the joint capsule, and biopsy confirms synovial sarcoma. Which of the following chromosomal translocations is highly specific for this diagnosis?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(9;22)(q22;q12)
. t(2;13)(q35;q14)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. This molecular marker is present in over 90% of cases.

Question 4660

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with pain and swelling over his distal femur. A biopsy reveals small blue round cells. Cytogenetic testing demonstrates a t(11;22) chromosomal translocation. Which fusion gene is pathognomonic for this patient's diagnosis?

. EWS-FLI1
. SYT-SSX
. TLS-CHOP
. PAX3-FKHR
. BCR-ABL

Correct Answer & Explanation

. EWS-FLI1

Explanation

The t(11;22) translocation results in the EWS-FLI1 fusion protein, which is diagnostic for Ewing sarcoma. This malignant bone tumor typically presents with a destructive lesion and an 'onion skin' periosteal reaction.

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