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10. Pathology and Oncology MCQs

Practice Set 22 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 421

Topic: Bone Tumors

A 15-year-old boy presents with progressive distal thigh pain that awakens him at night. Radiographs of the distal femur reveal an ill-defined, destructive, bone-forming lesion in the metaphysis accompanied by a sunburst periosteal reaction and a Codman's triangle. A core needle biopsy confirms a high-grade conventional osteosarcoma. What is the current standard of care sequence for this patient?

. Primary limb amputation followed by definitive radiotherapy
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Wide surgical resection alone with negative margins
. Neoadjuvant radiotherapy followed by limb-salvage surgery
. Intralesional curettage, bone grafting, and cryotherapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

The standard treatment for high-grade conventional osteosarcoma includes neoadjuvant chemotherapy, followed by wide surgical resection (limb-salvage or amputation), and subsequent adjuvant chemotherapy. This multidisciplinary approach significantly improves overall survival and limb preservation rates.

Question 422

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive thigh pain and a low-grade fever. Radiographs show a permeative, lytic lesion in the femoral diaphysis with an "onion-skin" periosteal reaction. A biopsy reveals small, round, blue cells. Which chromosomal translocation is most characteristically associated with this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by small, round, blue cells and a classic "onion-skin" periosteal reaction. It is strongly associated with the t(11;22)(q24;q12) chromosomal translocation, resulting in the EWS-FLI1 fusion gene.

Question 423

Topic: 10. Pathology and Oncology

A 33-year-old woman with cystic fibrosis dies while awaiting a lung transplant. She undergoes a post-mortem examination including a biopsy of the respiratory epithelium. Which of the following cells is likely to be found on the surface of the respiratory epithelium?

. Basophils
. Eosinophils
. Lymphocytes
. Monocytes
. Neutrophils

Correct Answer & Explanation

. Neutrophils

Explanation

Correct Answer: E- Neutrophils Explanation Neutrophil infiltration is well recognised as a determinant of progression in cystic fibrosis. Infiltration occurs early in the course of the disease, and neutrophil derived factors such as elastase lead to accelerated damage to the respiratory epithelium. Basophils Basophils (Option A) is incorrect. Basophilic infiltration is associated with fatal asthma. Eosinophils Eosinophils (Option B) is incorrect. Eosinophils are associated with allergic lung diseases. Lymphocytes Lymphocytes (Option C) is incorrect. Lymphocytic infiltration is associated with lymphocytic interstitial pneumonia. Monocytes Monocytes (Option D) is incorrect. Monocyte infiltration may be involved in the development of idiopathic pulmonary fibrosis.

Question 424

Topic: 10. Pathology and Oncology
A 50-year-old smoker was diagnosed with a non-small-cell carcinoma. Investigations revealed a 4 cm × 3 cm × 2 cm tumour in the lower lobe of his left lung that has invaded the visceral pleura. The ipsilateral hilar lymph node is also involved, but there is no metastatic involvement of any distal organ. What is the stage of disease in this patient?
. T2 N0 M0
. T2 N1 M0
. T3 N1 M0
. T4 N0 M0
. T4 N1 M0

Correct Answer & Explanation

. T2 N1 M0

Explanation

Correct Answer: T2 N1 M0. This is a 'know it or you don't' answer. It is important to remember the criteria for staging carcinoma of the lung. As the tumour is more than 3 cm in its greatest dimension and has only invaded the visceral pleura, it is designated T2. Metastasis to the ipsilateral peribronchial and/or ipsilateral hilar lymph nodes makes the nodal stage N1. Absence of distal metastasis is called M0. TNM staging takes into account: the size and position of the tumour (T), whether the cancer cells have spread into the lymph nodes (N), and whether the tumour has spread anywhere else in the body (M).

Question 425

Topic: 10. Pathology and Oncology

A 22-year-old athlete undergoes skeletal muscle biopsy for a metabolic study. In the process of normal skeletal muscle contraction, intracellular calcium release triggers cross-bridge cycling by directly binding to which of the following molecules?

. Actin
. Myosin heavy chain
. Tropomyosin
. Troponin C
. Adenosine triphosphate (ATP)

Correct Answer & Explanation

. Troponin C

Explanation

During muscle contraction, calcium ions released from the sarcoplasmic reticulum bind to Troponin C. This causes a conformational change that moves tropomyosin away from the myosin-binding sites on the actin filament.

Question 426

Topic: 10. Pathology and Oncology

A 19-year-old male undergoing general anesthesia for an open femur fracture suddenly exhibits unexplained tachycardia, generalized muscle rigidity, and a rapidly rising end-tidal CO2. If malignant hyperthermia is suspected, what is the primary pathophysiologic defect?

. Deficiency of pseudocholinesterase enzyme
. Mutation in the ryanodine receptor (RYR1) causing massive calcium release
. Autoantibodies targeting the voltage-gated calcium channels
. Impaired reuptake of serotonin in the synaptic cleft
. Hyperactivity of beta-adrenergic receptors

Correct Answer & Explanation

. Mutation in the ryanodine receptor (RYR1) causing massive calcium release

Explanation

Malignant hyperthermia is a pharmacogenetic disorder typically caused by a mutation in the ryanodine receptor (RYR1) on the sarcoplasmic reticulum, leading to uncontrolled, massive calcium release into the myoplasm.

Question 427

Topic: 10. Pathology and Oncology

A 55-year-old woman is being evaluated for metabolic bone disease. Her laboratory workup includes normal serum calcium, normal phosphorus, and normal parathyroid hormone levels, but an elevated bone-specific alkaline phosphatase. What does this specific marker primarily indicate?

. Increased osteoclastic bone resorption
. Increased osteoblastic bone formation
. Vitamin D deficiency
. Impaired renal reabsorption of calcium
. Malignant transformation of bone marrow cells

Correct Answer & Explanation

. Increased osteoblastic bone formation

Explanation

Bone-specific alkaline phosphatase and osteocalcin are biochemical markers of bone formation, reflecting active osteoblastic activity. Markers like N-telopeptide (NTx) and C-telopeptide (CTx) reflect osteoclastic bone resorption.

Question 428

Topic: 10. Pathology and Oncology

A 30-year-old man undergoes shoulder arthroscopy under general anesthesia. Thirty minutes into the case, he develops masseter spasm, unexplained tachycardia, and a sharply rising end-tidal CO2. What is the underlying pathophysiology of this life-threatening condition?

. Acetylcholinesterase deficiency
. Mutation in the RYR1 gene causing excessive calcium release
. Autoantibodies against presynaptic voltage-gated calcium channels
. Depletion of presynaptic dopamine
. Systemic local anesthetic toxicity

Correct Answer & Explanation

. Mutation in the RYR1 gene causing excessive calcium release

Explanation

The patient is experiencing malignant hyperthermia, triggered by volatile anesthetics or succinylcholine. It is caused by a mutation in the ryanodine receptor (RYR1), leading to massive uncontrolled calcium release from the sarcoplasmic reticulum.

Question 429

Topic: Bone Tumors

An orthopedic researcher wants to investigate the association between a rare primary bone malignancy (e.g., osteosarcoma) and a specific prior environmental exposure. Which epidemiological study design is the most appropriate and efficient for this scenario?

. Randomized controlled trial
. Prospective cohort study
. Case-control study
. Cross-sectional study
. Ecological study

Correct Answer & Explanation

. Case-control study

Explanation

A case-control study is the most efficient design for evaluating rare diseases. It retrospectively compares previous exposures between a group with the disease (cases) and a group without the disease (controls).

Question 430

Topic: 10. Pathology and Oncology

What is the most important prognostic factor for long-term survival in a patient with localized, non-metastatic osteosarcoma of the distal femur?

. Tumor volume at presentation
. Initial serum alkaline phosphatase level
. Percentage of histologic necrosis following neoadjuvant chemotherapy
. Age of the patient at the time of diagnosis
. Anatomic location of the tumor

Correct Answer & Explanation

. Percentage of histologic necrosis following neoadjuvant chemotherapy

Explanation

The percentage of histologic tumor necrosis after neoadjuvant chemotherapy is the most critical prognostic indicator in localized osteosarcoma. A good response, defined as greater than 90% necrosis, correlates strongly with improved disease-free and overall survival rates.

Question 431

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. A biopsy is planned. Which specific chromosomal translocation is most characteristically associated with this pathology?

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

Correct Answer & Explanation

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

Explanation

Ewing sarcoma is classically characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. Synovial sarcoma is t(X;18), and myxoid liposarcoma is t(12;16).

Question 432

Topic: 10. Pathology and Oncology

A 32-year-old male presents with a slowly enlarging, painful mass near his knee joint. MRI reveals a soft tissue mass adjacent to the joint space. Biopsy demonstrates a biphasic pattern of spindle cells and epithelial cells. Which of the following chromosomal translocations is most characteristic of this lesion?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, which results in the SYT-SSX fusion gene. It commonly presents in young adults as a calcified soft tissue mass near, but rarely within, a joint.

Question 433

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain. Radiographs reveal a sunburst periosteal reaction and Codman's triangle in the distal femur. Biopsy confirms osteosarcoma. What is the most significant prognostic factor for long-term survival in this patient?

. Tumor size at the time of diagnosis
. Histologic subtype of the osteosarcoma
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Initial serum alkaline phosphatase level
. Patient age at presentation

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The most critical prognostic factor for localized osteosarcoma is the histological response to neoadjuvant chemotherapy. Greater than 90% tumor necrosis is associated with significantly improved long-term overall survival.

Question 434

Topic: Bone Tumors

A 65-year-old man presents with a pathologic subtrochanteric femur fracture. Laboratory workup reveals hypercalcemia, renal insufficiency, and anemia. Serum protein electrophoresis shows an M-spike. Which of the following radiographic findings is most characteristic of this patient's underlying disease?

. Diffuse osteoblastic lesions
. "Punched-out" lytic lesions without sclerotic margins
. Sunburst periosteal reaction
. Ground-glass matrix
. Soap-bubble expansile lesion

Correct Answer & Explanation

. "Punched-out" lytic lesions without sclerotic margins

Explanation

The patient's clinical presentation is classic for multiple myeloma. The characteristic radiographic appearance includes multiple "punched-out" lytic bone lesions lacking a reactive sclerotic rim due to simultaneous osteoclast activation and osteoblast inhibition.

Question 435

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain. Radiographs reveal a metaphyseal permeative lesion in the distal femur with a "sunburst" periosteal reaction. Biopsy shows malignant spindle cells producing unmineralized osteoid. What is the most likely diagnosis?

. Ewing sarcoma
. Chondrosarcoma
. Osteosarcoma
. Non-ossifying fibroma
. Osteoblastoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

The production of osteoid by malignant mesenchymal cells is the histological hallmark of osteosarcoma. A "sunburst" periosteal reaction in the metaphysis of a teenager further supports this diagnosis over Ewing sarcoma.

Question 436

Topic: Bone Tumors

A 65-year-old man with hypercalcemia and an M-spike on protein electrophoresis has multiple "punched-out" skull lesions. Which is the most appropriate initial screening test to evaluate for impending pathologic appendicular fractures?

. Technetium-99m bone scan
. Whole-body MRI
. Skeletal survey with plain radiographs
. PET-CT scan
. Dual-energy X-ray absorptiometry (DEXA)

Correct Answer & Explanation

. Skeletal survey with plain radiographs

Explanation

Multiple myeloma lesions are purely lytic and often lack an osteoblastic response, leading to "cold" or false-negative results on a bone scan. A complete plain radiographic skeletal survey is the standard initial imaging modality.

Question 437

Topic: 10. Pathology and Oncology

A 16-year-old male presents with distal thigh pain. Radiographs reveal a destructive metaphyseal lesion with a "sunburst" periosteal reaction. A core needle biopsy confirms high-grade osteosarcoma. Which of the following is the most critical prognostic factor for his overall survival?

. Histologic subtype of the tumor
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Baseline serum alkaline phosphatase level
. Patient's age at the time of diagnosis
. Volume of the soft tissue extension

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The histologic response to neoadjuvant chemotherapy is the single most important prognostic factor in high-grade osteosarcoma. A response of greater than 90% tumor necrosis correlates with significantly improved long-term survival.

Question 438

Topic: 10. Pathology and Oncology

A 16-year-old girl presents with a destructive diaphyseal lesion of the femur. Radiographs reveal a large soft tissue mass and an "onion skin" periosteal reaction. Histological examination shows sheets of small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

This patient has Ewing sarcoma, a malignant bone tumor classically presenting with an "onion skin" periosteal reaction and sheets of small round blue cells on histology. It is most strongly associated with the t(11;22) chromosomal translocation, which produces the characteristic EWS-FLI1 fusion protein.

Question 439

Topic: Bone Tumors

Aneurysmal bone cyst of the spine is most likely in this age group:

. First decade
. Second decade
. Third decade
. Fourth decade
. Fifth decade

Correct Answer & Explanation

. Second decade

Explanation

The most common age is the second decade; the mean age is 13 years old for patients with this disorder.

Question 440

Topic: 10. Pathology and Oncology

A 14-year-old girl is examined because of a pain in her left flank. The radiographs of the lumbar spine show loss of the pedicle with expansion of the lateral wall of the third lumbar vertebral body. Magnetic resonance imaging shows multiple fluid levels with no additional areas of involvement. She is neurologically normal. Recommended treatment includes:

. Observation
. Radiation therapy
. Selective arterial embolization
. Radical en bloc resection
. C urettage plus radiation therapy

Correct Answer & Explanation

. Selective arterial embolization

Explanation

This patient has an aneurysmal bone cyst. Selective arterial embolization is a minimally invasive treatment that often succeeds in arresting the lesions. Many times it is the only treatment needed. Selective arterial embolization can also be used as part of a strategy to be followed by curettage and reconstruction to decrease operative bleeding. This lesion will continue to expand and might cause neurologic compromise or mechanical instability. Radiation therapy poses risks of later malignant degeneration. There are other ways of treating this lesion. Radical en bloc resection may unnecessarily injure neurologic structures. While curettage is often necessary, there is no reason to introduce the risk of radiation therapy.

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