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10. Pathology and Oncology MCQs

Practice Set 162 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 3221

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with chronic, dull back pain. He states the pain is constant and does not significantly improve with ibuprofen. Radiographs are shown.

Which of the following describes the most likely diagnosis?

. Typically less than 1.5 cm in diameter
. Demonstrates a nidus producing high levels of prostaglandins with dramatic NSAID relief
. Locally aggressive, expansile lesion greater than 2 cm typically found in the posterior elements
. Malignant spindle cells producing osteoid matrix
. Most commonly occurs in the anterior vertebral body

Correct Answer & Explanation

. Locally aggressive, expansile lesion greater than 2 cm typically found in the posterior elements

Explanation

Osteoblastoma is a benign but locally aggressive bone tumor typically >2 cm. It favors the posterior elements of the spine and, unlike osteoid osteoma, pain is usually not dramatically relieved by NSAIDs.

Question 3222

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive back pain that is poorly responsive to NSAIDs. Neurological examination is normal. Radiographs are shown below.

Which of the following characteristics best differentiates this lesion from an osteoid osteoma?

. Pain is classically relieved rapidly by aspirin
. Size is typically less than 1.5 cm
. Higher propensity for progressive growth, aggressive behavior, and neural compression
. Typically occurs in the anterior vertebral body rather than posterior elements
. Pathologically shows a dense fibrous stroma completely devoid of osteoid

Correct Answer & Explanation

. Higher propensity for progressive growth, aggressive behavior, and neural compression

Explanation

The clinical and radiographic presentation is consistent with an osteoblastoma, which is classically >2 cm, progressively enlarging, and does not predictably respond to NSAIDs. Osteoblastomas have a higher rate of local recurrence and can cause neurological deficit due to expansile growth. Both tumors prefer the posterior elements of the spine.

Question 3223

Topic: Bone Tumors

A 16-year-old girl undergoes intralesional curettage of an expansile 3.5 cm lytic lesion located in the posterior elements of C4. A photomicrograph of the specimen is shown.

What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

The histology demonstrates loose fibrovascular connective tissue intermixed with irregular osteoid, typical of osteoblastoma. The lesion size (3.5 cm) rules out osteoid osteoma, which has identical histology but is <2 cm.

Question 3224

Topic: 10. Pathology and Oncology

An 11-year-old boy presents with severe, deep thigh pain and fever. Radiographs show a permeative diaphyseal lesion with an "onion-skin" periosteal reaction. A core biopsy demonstrates uniform small round blue cells. Which specific genetic translocation is most diagnostic of this malignancy?

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

Correct Answer & Explanation

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

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein in about 85% of cases. It classically presents as a permeative, diaphyseal lesion in children.

Question 3225

Topic: Bone Tumors

A 15-year-old boy presents with a rapidly expanding, destructive metaphyseal lesion of the distal femur. MRI reveals large fluid-fluid levels. Histology shows highly pleomorphic, atypical spindle cells producing fine, lace-like osteoid within the septa separating blood-filled spaces. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Unicameral bone cyst
. Telangiectatic osteosarcoma
. Giant cell tumor
. Osteoblastoma

Correct Answer & Explanation

. Telangiectatic osteosarcoma

Explanation

While aneurysmal bone cysts (ABCs) feature fluid-fluid levels and blood-filled spaces, the presence of atypical, highly pleomorphic spindle cells and malignant osteoid production within the septa is diagnostic of telangiectatic osteosarcoma. This distinction is critical as treatment requires neoadjuvant chemotherapy and wide resection.

Question 3226

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with progressive back pain that awakens him at night and is not relieved by ibuprofen. Imaging shows a 3-cm expansile lytic lesion in the posterior elements of L3. Biopsy reveals the following histology.

What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastoma is typically larger than 2 cm, occurs frequently in the posterior elements of the spine, and causes pain that is classically not relieved by NSAIDs. Histology shows loose fibrovascular connective tissue intermixed with irregular osteoid.

Question 3227

Topic: 10. Pathology and Oncology

A 12-year-old boy has a permeative lytic lesion in the femoral diaphysis with an associated "onion-skin" periosteal reaction. Biopsy reveals sheets of uniform small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is a small round blue cell tumor that classically presents in the diaphysis of long bones with an onion-skin periosteal reaction. It is characterized by the t(11;22) translocation resulting in the EWS-FLI1 fusion gene.

Question 3228

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain. Radiographs reveal a well-circumscribed, eccentrically located lytic lesion with a sclerotic margin, entirely contained within the proximal tibial epiphysis. Histology shows mononuclear cells, osteoclast-like giant cells, and areas of "chicken-wire" calcification. What is the diagnosis?

. Giant cell tumor
. Chondroblastoma
. Clear cell chondrosarcoma
. Osteosarcoma
. Osteoid osteoma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare, benign cartilaginous tumor that characteristically arises in the epiphysis or apophysis of long bones in children with open physes. Histology classically demonstrates "chicken-wire" calcifications.

Question 3229

Topic: Bone Tumors

An 8-year-old boy sustains a minor twisting injury to his arm and complains of shoulder pain. Radiographs show a centrally located, completely radiolucent lesion in the proximal humeral metaphysis extending to the physis. A small fragment of bone is seen resting at the dependent portion of the cyst. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Unicameral bone cyst
. Non-ossifying fibroma
. Fibrous dysplasia
. Enchondroma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

The description is classic for a unicameral bone cyst (simple bone cyst). The "fallen leaf" or "fallen fragment" sign indicates a pathologic fracture through a fluid-filled cystic lesion, which is highly suggestive of a UBC.

Question 3230

Topic: Bone Tumors

A 15-year-old male presents with chronic back pain, which is worse at night and incompletely relieved by NSAIDs. Radiographs reveal an expansile, lytic lesion in the posterior elements of L3.

Based on the clinical presentation and typical radiographic findings shown, what is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Osteosarcoma
. Ewing sarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastoma typically presents as an expansile lytic lesion >2 cm in the posterior elements of the spine. Unlike osteoid osteoma, the pain is generally dull, aching, and less likely to be completely relieved by NSAIDs.

Question 3231

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with distal femur pain. Radiographs demonstrate a mixed lytic and sclerotic lesion with a sunburst periosteal reaction. A core needle biopsy is performed. What histologic feature is mandatory for the diagnosis of osteosarcoma?

. Cartilage capping
. Blue cell proliferation
. Production of malignant osteoid directly by tumor cells
. Herringbone spindle cell pattern
. Multinucleated giant cells in a hemorrhagic background

Correct Answer & Explanation

. Production of malignant osteoid directly by tumor cells

Explanation

The defining histologic characteristic of osteosarcoma is the production of malignant osteoid or immature bone directly by malignant mesenchymal cells. This distinguishes it from other high-grade sarcomas.

Question 3232

Topic: 10. Pathology and Oncology

A 10-year-old girl is diagnosed with a diaphyseal femur tumor characterized by onion-skin periosteal reaction and CD99-positive small round blue cells. What is the most common cytogenetic translocation associated with this tumor?

. 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 characterized by the t(11;22)(q24;q12) translocation in approximately 85% of cases. This results in the EWS-FLI1 fusion protein, which drives tumor pathogenesis.

Question 3233

Topic: 10. Pathology and Oncology

A 19-year-old male with chronic neck pain undergoes biopsy of an expansile lesion in the C4 lamina. Histology is shown below.

Based on the photomicrograph and clinical presentation, what is the most appropriate definitive management?

. Extended course of NSAIDs
. Radiation therapy
. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy followed by wide resection
. Observation only

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

The image demonstrates osteoblastoma, characterized by loose fibrovascular connective tissue intermixed with irregular osteoid. Treatment consists of surgical excision, typically via thorough intralesional curettage and bone grafting or marginal en bloc resection.

Question 3234

Topic: 10. Pathology and Oncology

A 6-year-old boy from Connecticut presents with an acute, massive right knee effusion and an intermittent limp. He is afebrile, and the joint aspirate yields 45,000 WBCs/mm3. What diagnostic test sequence is recommended to confirm the suspected diagnosis?

. Synovial fluid Gram stain and bacterial culture
. Enzyme immunoassay (EIA) followed by Western blot
. Synovial biopsy for acid-fast bacilli
. Peripheral blood smear for intracellular parasites
. Antinuclear antibody and rheumatoid factor testing

Correct Answer & Explanation

. Enzyme immunoassay (EIA) followed by Western blot

Explanation

Lyme arthritis typically presents with a large, minimally tender effusion in endemic areas. Diagnosis relies on two-tier serologic testing: an initial enzyme immunoassay (EIA) followed by a confirmatory Western blot.

Question 3235

Topic: 10. Pathology and Oncology

An 8-year-old boy presents with mild shoulder pain after throwing a baseball. X-rays reveal a centrally located, lytic, slightly expansile lesion in the proximal humerus metaphysis with a visible "fallen leaf" sign. Which of the following is true regarding the management of this lesion?

. It has a high rate of malignant transformation to osteosarcoma.
. Pathologic fractures through this lesion almost never heal without internal fixation.
. Corticosteroid or bone marrow aspirate injection is a standard first-line treatment.
. It eccentrically expands the cortex leading to rapid joint destruction.
. Marginal en bloc resection is mandatory to prevent recurrence.

Correct Answer & Explanation

. Corticosteroid or bone marrow aspirate injection is a standard first-line treatment.

Explanation

The "fallen leaf" sign is pathognomonic for a Unicameral Bone Cyst (UBC). First-line treatment for active, symptomatic, or fracture-prone UBCs often includes minimally invasive techniques like corticosteroid or bone marrow aspirate injections.

Question 3236

Topic: 10. Pathology and Oncology

A 17-year-old male presents with persistent, dull aching pain in his mid-back that is not reliably relieved by NSAIDs. Imaging shows a 3.5 cm expansile radiolucent lesion in the posterior elements of T10. Biopsy is performed and reveals the following histology:

What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Giant cell tumor
. Osteosarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

The presentation of a spinal posterior element lesion >2 cm with histology showing loose fibrovascular stroma and irregular osteoid is characteristic of osteoblastoma. Unlike osteoid osteoma, the pain is often less responsive to NSAIDs and the lesion exceeds 1.5-2.0 cm.

Question 3237

Topic: Bone Tumors

A 12-year-old boy presents with pain and swelling in his mid-thigh. Radiographs show a permeative diaphyseal lesion with an "onion skin" periosteal reaction. Genetic testing reveals a t(11;22) chromosomal translocation. What fusion protein is associated with this specific translocation?

. SYT-SSX1
. EWS-FLI1
. TLS-CHOP
. PAX3-FKHR
. BCR-ABL

Correct Answer & Explanation

. EWS-FLI1

Explanation

Ewing sarcoma is classically associated with the t(11;22) chromosomal translocation. This specific translocation results in the production of the aberrant EWS-FLI1 fusion protein.

Question 3238

Topic: Bone Tumors

A 5-year-old African American child with homozygous sickle cell disease presents with high fever and severe left arm pain. Radiographs show periosteal elevation of the radial diaphysis. While Staphylococcus aureus remains common, which of the following organisms is disproportionately frequent in this specific patient population?

. Pseudomonas aeruginosa
. Neisseria gonorrhoeae
. Salmonella species
. Haemophilus influenzae
. Kingella kingae

Correct Answer & Explanation

. Salmonella species

Explanation

Children with sickle cell disease are particularly susceptible to Salmonella osteomyelitis due to functional asplenia and localized bone infarcts serving as a nidus. However, S. aureus is still an overall common cause in these patients.

Question 3239

Topic: Bone Tumors

An 11-year-old boy presents with night-time right thigh pain that dramatically improves within 30 minutes of taking ibuprofen. Radiographs demonstrate a dense sclerotic lesion in the proximal femur with a 1-cm central radiolucent nidus. What is the most common definitive treatment currently utilized for this condition?

. Wide surgical excision
. Intralesional curettage and bone grafting
. Radiofrequency ablation (RFA)
. External beam radiation
. Systemic chemotherapy

Correct Answer & Explanation

. Radiofrequency ablation (RFA)

Explanation

The clinical presentation is classic for an osteoid osteoma. Percutaneous radiofrequency ablation (RFA) under CT guidance is the standard of care for definitive treatment, offering high success rates with minimal morbidity compared to open surgery.

Question 3240

Topic: 10. Pathology and Oncology

A 14-year-old boy with a family history of Multiple Hereditary Exostoses (MHE) is evaluated for a rapidly growing bump on his distal femur. What is the approximate lifetime risk of malignant transformation of an osteochondroma in patients with MHE?

. < 1%
. 1-5%
. 10-20%
. 30-50%
. > 75%

Correct Answer & Explanation

. 1-5%

Explanation

The risk of malignant transformation of an osteochondroma to a secondary chondrosarcoma is approximately 1-5% in patients with Multiple Hereditary Exostoses. This is significantly higher than the risk in patients with isolated, solitary osteochondromas (<1%).

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