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10. Pathology and Oncology MCQs

Practice Set 165 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 3281

Topic: 10. Pathology and Oncology

A 14-year-old boy has an eccentric, expansile, lytic metaphyseal lesion in his proximal humerus. MRI demonstrates multiple fluid-fluid levels. Genetic analysis of the tissue would most likely reveal a translocation involving which of the following genes?

. EWSR1
. SYT-SSX
. USP6
. RUNX2
. EXT1

Correct Answer & Explanation

. USP6

Explanation

Primary aneurysmal bone cysts (ABCs) are genuine neoplasms characterized by rearrangements of the USP6 gene on chromosome 17p13. MRI classically shows fluid-fluid levels due to blood settling within the cystic spaces.

Question 3282

Topic: Bone Tumors

A 60-year-old man presents with deep thigh pain. Radiographs reveal a large diaphyseal lesion in the femur with endosteal scalloping greater than two-thirds of the cortical thickness and \"popcorn\" calcifications. What is the mainstay of treatment for this lesion?

. Neoadjuvant chemotherapy followed by wide resection
. Intralesional curettage with phenol adjuvant
. Wide surgical resection alone
. Radiation therapy followed by wide resection
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

The patient has a conventional chondrosarcoma, indicated by age, endosteal scalloping, and chondroid matrix calcifications. Conventional chondrosarcomas are highly resistant to both chemotherapy and radiation, making wide surgical resection the primary treatment.

Question 3283

Topic: 10. Pathology and Oncology

When performing an incisional biopsy of a suspected malignant primary bone tumor in the distal femur, which of the following principles must be strictly adhered to?

. Use a transverse incision to minimize tension on the skin
. Expose major neurovascular bundles to ensure they are protected
. Place the biopsy tract in line with the planned definitive resection incision
. Achieve hemostasis by packing the wound with bone wax
. Elevate a large subfascial flap to visualize the entire tumor boundary

Correct Answer & Explanation

. Place the biopsy tract in line with the planned definitive resection incision

Explanation

Biopsy tracts are considered contaminated with tumor cells and must be entirely excised during definitive tumor resection. Therefore, the biopsy incision must be longitudinal and placed directly in line with the planned surgical approach, avoiding neurovascular structures.

Question 3284

Topic: 10. Pathology and Oncology
In a patient who has undergone neoadjuvant chemotherapy and wide resection for a conventional osteosarcoma of the distal femur, which of the following histologic findings is the most significant prognostic indicator for long-term survival?
. The presence of chondroblastic rather than osteoblastic differentiation
. A high mitotic index in the resected specimen
. Greater than 90% tumor necrosis in the resection specimen
. Positive staining for alkaline phosphatase
. The degree of periosteal reactive bone formation

Correct Answer & Explanation

. Greater than 90% tumor necrosis in the resection specimen

Explanation

The histologic response to neoadjuvant chemotherapy, defined by the percentage of tumor necrosis, is the single most important prognostic factor in osteosarcoma. Greater than 90% necrosis (Huvos grade III/IV) correlates with a significantly higher survival rate.

Question 3285

Topic: 10. Pathology and Oncology

A biopsy is planned for a suspected high-grade sarcoma of the distal femur. Which of the following is a critical principle when performing the incisional biopsy?

. The biopsy incision should be transverse to minimize the cosmetic scar
. The biopsy tract must be placed in line with the definitive surgical resection incision
. A tourniquet should be utilized and exsanguinated by wrapping an Esmarch bandage over the tumor
. Extensive subperiosteal dissection should be performed to ensure an adequate sample
. The biopsy should be taken from the central necrotic portion of the tumor

Correct Answer & Explanation

. The biopsy tract must be placed in line with the definitive surgical resection incision

Explanation

A biopsy tract is considered contaminated and must be excised en bloc during definitive tumor resection. Therefore, the biopsy incision must be longitudinal and placed directly in line with the planned surgical approach.

Question 3286

Topic: 10. Pathology and Oncology

A 16-year-old girl is diagnosed with Ewing sarcoma of the femoral diaphysis. Cytogenetic analysis of the tumor cells is most likely to reveal which of the following translocations?

. t(X;18) (SYT-SSX)
. t(11;22) (EWS-FLI1)
. t(12;16) (FUS-CHOP)
. t(9;22) (BCR-ABL)
. t(2;13) (PAX3-FOXO1)

Correct Answer & Explanation

. t(11;22) (EWS-FLI1)

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation in approximately 85% of cases, resulting in the EWS-FLI1 fusion protein. This molecular marker is highly specific and used for diagnostic confirmation.

Question 3287

Topic: Bone Tumors

A 55-year-old male undergoes wide surgical resection for a conventional Grade II chondrosarcoma of the proximal femur. Which of the following best describes the role of adjuvant therapy for this condition?

. Standard multi-agent chemotherapy should be administered postoperatively
. Postoperative external beam radiation is required for local control
. Adjuvant therapy is generally ineffective; wide surgical margins are the mainstay of treatment
. Targeted therapy with denosumab is indicated to prevent recurrence
. Intralesional radiofrequency ablation should follow the resection

Correct Answer & Explanation

. Adjuvant therapy is generally ineffective; wide surgical margins are the mainstay of treatment

Explanation

Conventional chondrosarcomas are notably resistant to both chemotherapy and radiotherapy. The mainstay of curative treatment relies solely on achieving wide surgical resection margins.

Question 3288

Topic: Bone Tumors

A 16-year-old male complains of severe back pain, especially at night. Imaging reveals a 2.5 cm lytic lesion with central calcification in the posterior elements of L4. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Ewing sarcoma
. Multiple myeloma

Correct Answer & Explanation

. Osteoblastoma

Explanation

While both osteoid osteoma and osteoblastoma have similar histology, an osteoblastoma is distinguished by a nidus size greater than 2 cm and a predilection for the posterior elements of the spine. Osteoblastomas are also less predictably relieved by NSAIDs compared to osteoid osteomas.

Question 3289

Topic: 10. Pathology and Oncology

A 65-year-old male presents with bone pain and a pathologic fracture of the proximal humerus. Radiographs show multiple "punched-out" lytic lesions. A technetium-99m bone scan is performed and shows no significant uptake in the lesions. What is the most likely diagnosis?

. Metastatic prostate cancer
. Metastatic breast cancer
. Multiple myeloma
. Paget's disease of bone
. Osteosarcoma

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma lesions characteristically appear as "cold" or show no increased uptake on a technetium-99m bone scan. This is because myeloma cells secrete factors that suppress osteoblastic activity, and bone scans primarily detect osteoblast-mediated bone turnover.

Question 3290

Topic: 10. Pathology and Oncology

A 30-year-old male presents with an eccentric, purely lytic lesion in the epiphysis of the distal femur extending to the subchondral bone. Biopsy confirms Giant Cell Tumor (GCT). If systemic therapy is considered, which of the following agents is most appropriate?

. Imatinib
. Denosumab
. Methotrexate
. Doxorubicin
. Rituximab

Correct Answer & Explanation

. Denosumab

Explanation

Denosumab is a monoclonal antibody against RANKL, which is the primary cytokine driving bone destruction in Giant Cell Tumor of bone. It is used as targeted therapy to consolidate the tumor, especially in unresectable or recurrent cases.

Question 3291

Topic: 10. Pathology and Oncology

A 22-year-old patient with Multiple Hereditary Exostoses (MHE) reports new, increasing pain and sudden growth of a previously stable lesion on the proximal tibia. What specific imaging finding is most indicative of malignant transformation?

. A cartilage cap thickness greater than 2 cm on MRI
. Presence of a medullary cavity continuous with the host bone
. A pedicle pointing away from the joint line
. The appearance of "cauliflower-like" calcifications
. A sclerotic margin surrounding the base of the lesion

Correct Answer & Explanation

. A cartilage cap thickness greater than 2 cm on MRI

Explanation

In adults, a cartilage cap thicker than 2 cm (or 1.5 cm in some literature) on MRI is highly suspicious for malignant transformation of an osteochondroma into a secondary chondrosarcoma. Growth of a lesion or new pain after skeletal maturity also strongly suggests malignancy.

Question 3292

Topic: 10. Pathology and Oncology

Aneurysmal bone cysts (ABCs) are expansile, blood-filled cystic lesions. While they can be secondary to other tumors, primary ABCs are now known to be true neoplasms driven by a specific genetic rearrangement. Which gene translocation is diagnostic for a primary ABC?

. USP6 (17p13)
. EWS-FLI1 (t(11;22))
. SYT-SSX (t(X;18))
. MDM2 amplification
. GNAS mutation

Correct Answer & Explanation

. USP6 (17p13)

Explanation

Primary Aneurysmal Bone Cysts are characterized by translocations involving the USP6 gene on chromosome 17p13. This finding helps differentiate primary ABCs from secondary ABC-like changes that occur in other tumors like giant cell tumor or osteoblastoma.

Question 3293

Topic: 10. Pathology and Oncology

A biopsy of a lesion suspected to be Dysplasia Epiphysealis Hemimelica (DEH) is sent for histological examination. The pathologist notes that the tissue is histologically indistinguishable from which of the following benign bone tumors?

. Chondroblastoma
. Osteoid osteoma
. Osteochondroma
. Enchondroma

Correct Answer & Explanation

. Osteochondroma

Explanation

Correct Answer: OsteochondromaHistologically, DEH is similar to an osteochondroma. However, they are distinguished by their site of origin: an osteochondroma arises from the metaphysis or diaphysis, whereas DEH arises from the epiphysis.

Question 3294

Topic: Bone Tumors

Which of the following radiographic findings is the hallmark of Dysplasia Epiphysealis Hemimelica?

. Symmetrical epiphyseal enlargement with a single central ossification center
. Asymmetric epiphyseal enlargement with multiple ossification centers
. Metaphyseal flaring with a pedunculated bony exostosis
. Diaphyseal cortical thickening with a radiolucent nidus

Correct Answer & Explanation

. Asymmetric epiphyseal enlargement with multiple ossification centers

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centersCharacteristically, DEH lesions show on radiographs as asymmetric epiphyseal enlargement with multiple ossification centers, reflecting the hemimelic (one-sided) nature of the epiphyseal involvement.

Question 3295

Topic: Bone Tumors

While Dysplasia Epiphysealis Hemimelica (DEH) shares histological similarities with osteochondroma, it is primarily distinguished by its site of origin. From which specific anatomical region of the bone does DEH arise?

. Diaphysis
. Metaphysis
. Epiphysis
. Physis (growth plate) exclusively

Correct Answer & Explanation

. Epiphysis

Explanation

Correct Answer: EpiphysisDEH is a developmental disorder affecting the epiphyses in young children. This is a key distinguishing factor from osteochondromas, which arise from the metaphysis or diaphysis.

Question 3296

Topic: Bone Tumors

A 6-year-old boy presents with the clinical appearance shown below. Palpation reveals a bone-hard mass. Based on the most likely diagnosis, what is the expected histological appearance of this lesion?


. Identical to an osteoid osteoma
. Identical to an osteochondroma
. Identical to an enchondroma
. Identical to a chondroblastoma
. Identical to an osteosarcoma

Correct Answer & Explanation

. Identical to an osteochondroma

Explanation

Correct Answer: Identical to an osteochondromaThe clinical image demonstrates a moderate, painless, bone-hard swelling at the lateral side of the ankle, characteristic of Dysplasia Epiphysealis Hemimelica (DEH). Histologically, DEH lesions are similar to osteochondromas. However, they are distinguished by their origin: DEH arises from the epiphysis, whereas osteochondromas arise from the metaphysis or diaphysis.

Question 3297

Topic: Bone Tumors

A 12-year-old boy presents with limited range of motion in his knee. Imaging is provided below. The mass protrudes from the distal femoral epiphysis into the popliteal fossa. How does this condition primarily differ from an osteochondroma?


. It has a completely different histological appearance
. It arises from the epiphysis rather than the metaphysis or diaphysis
. It predominantly affects the upper limbs
. It is more common in females
. It typically presents in adulthood

Correct Answer & Explanation

. It arises from the epiphysis rather than the metaphysis or diaphysis

Explanation

Correct Answer: It arises from the epiphysis rather than the metaphysis or diaphysisThe imaging demonstrates Dysplasia Epiphysealis Hemimelica (DEH) of the distal femur. While histologically similar to an osteochondroma, DEH is uniquely characterized by its origin from the epiphysis. Osteochondromas classically arise from the metaphysis or diaphysis.

Question 3298

Topic: 10. Pathology and Oncology

A 7-year-old boy presents with aching pain and a bone-hard mass on the medial aspect of his knee. Radiographs show asymmetric epiphyseal enlargement with multiple ossification centers. A biopsy is taken. The pathologist is most likely to report findings consistent with which of the following?

. Chondromyxoid fibroma
. Giant cell tumor of bone
. Aneurysmal bone cyst
. Eosinophilic granuloma
. Osteochondroma

Correct Answer & Explanation

. Osteochondroma

Explanation

Correct Answer: OsteochondromaThe clinical and radiographic presentation is classic for Dysplasia Epiphysealis Hemimelica (DEH). Histologically, the lesion is similar to an osteochondroma, consisting of a bony outgrowth covered by a cartilage cap, but it is distinguished by its epiphyseal origin.

Question 3299

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with the clinical appearance shown below. Palpation reveals a bone-hard, painless mass. Given the most likely diagnosis of Dysplasia Epiphysealis Hemimelica, which of the following is the most common histological finding of this lesion?




. Chondroblastoma-like cells with chicken-wire calcification
. Histologically identical to an osteochondroma
. Malignant spindle cells producing osteoid
. Benign proliferation of fibrous tissue and woven bone

Correct Answer & Explanation

. Histologically identical to an osteochondroma

Explanation

Correct Answer: Histologically identical to an osteochondromaAccording to the text, Dysplasia Epiphysealis Hemimelica (DEH) is histologically similar/identical to an osteochondroma. The key differentiating factor is anatomical location: osteochondromas arise from the metaphysis or diaphysis, whereas DEH arises from the epiphysis.

Question 3300

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with a bony mass around the knee. A biopsy is performed, and the pathologist notes that the histology is identical to an osteochondroma. Which of the following radiographic features would definitively differentiate Dysplasia Epiphysealis Hemimelica (DEH) from a standard osteochondroma in this patient?

. The presence of a cartilage cap
. The lesion arising directly from the epiphysis
. The lesion arising from the metaphysis
. The presence of multiple ossification centers in the diaphysis

Correct Answer & Explanation

. The lesion arising directly from the epiphysis

Explanation

Correct Answer: The lesion arising directly from the epiphysisWhile DEH and osteochondroma share identical histological features, they are differentiated by their site of origin. Osteochondromas arise from the metaphysis or diaphysis, whereas DEH arises exclusively from the epiphysis.

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