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10. Pathology and Oncology MCQs

Practice Set 286 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 5701

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a destructive metaphyseal lesion in the distal femur with an associated soft tissue mass and a 'sunburst' periosteal reaction. Which of the following pairs of tumor suppressor genes are most commonly mutated or inactivated in the pathogenesis of this specific tumor?

. EXT1 and EXT2
. RB1 and TP53
. PTEN and APC
. NF1 and NF2
. SMARCB1 and EWSR1

Correct Answer & Explanation

. RB1 and TP53

Explanation

The clinical and radiographic presentation describes conventional osteosarcoma. The pathogenesis of osteosarcoma is strongly associated with mutations in the tumor suppressor genes RB1 (Retinoblastoma gene) and TP53 (p53). Patients with hereditary retinoblastoma (RB1 mutation) and Li-Fraumeni syndrome (TP53 mutation) have a significantly increased risk of developing osteosarcoma.

Question 5702

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, destructive diaphyseal lesion of the left femur and an associated large soft tissue mass. Biopsy reveals uniform, small, round, blue cells expressing CD99. What is the most common cytogenetic abnormality associated with this tumor?

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

Correct Answer & Explanation

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

Explanation

The clinical presentation and histology are classic for Ewing sarcoma. Over 85% of Ewing sarcomas are characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma; t(12;16) in myxoid liposarcoma; t(2;13) in alveolar rhabdomyosarcoma.

Question 5703

Topic: 10. Pathology and Oncology

Humoral hypercalcemia of malignancy is a paraneoplastic syndrome commonly caused by tumor secretion of Parathyroid Hormone-related Protein (PTHrP). Which of the following primary carcinomas is most classically associated with PTHrP secretion?

. Prostate adenocarcinoma
. Small cell carcinoma of the lung
. Papillary thyroid carcinoma
. Squamous cell carcinoma of the lung
. Multiple myeloma

Correct Answer & Explanation

. Squamous cell carcinoma of the lung

Explanation

Squamous cell carcinomas (especially of the lung, head, and neck), renal cell carcinoma, and breast carcinoma are classic sources of PTHrP. PTHrP mimics PTH by binding to the PTH-1 receptor, leading to increased bone resorption and hypercalcemia. Small cell lung cancer is more commonly associated with ACTH or ADH secretion. Prostate cancer usually causes osteoblastic lesions, not typically hypercalcemia via PTHrP.

Question 5704

Topic: 10. Pathology and Oncology

A 65-year-old female with metastatic breast cancer presents with a lytic lesion in the peritrochanteric region of the femur. The lesion measures 50% of the cortical diameter. She reports moderate pain with weight-bearing. Using Mirels' criteria, what is her calculated score and the most appropriate management?

. Score 7 - Observation and bisphosphonates
. Score 8 - Radiation therapy alone
. Score 9 - Cast immobilization
. Score 10 - Prophylactic internal fixation
. Score 12 - Amputation

Correct Answer & Explanation

. Score 10 - Prophylactic internal fixation

Explanation

Mirels' criteria score is calculated based on 4 variables (Site, Pain, Lesion, Size), assigning 1, 2, or 3 points for each. Site: Peritrochanteric = 3. Pain: Moderate = 2. Lesion: Lytic = 3. Size: 1/3 to 2/3 (50%) = 2. Total score = 3 + 2 + 3 + 2 = 10. A score of >/= 9 indicates impending pathologic fracture and prophylactic internal fixation is highly recommended.

Question 5705

Topic: 10. Pathology and Oncology

A 15-year-old male presents with a destructive, sunburst-pattern bone tumor in the distal femur. Biopsy confirms high-grade intramedullary osteosarcoma. A thorough family history reveals that his mother had breast cancer at age 32, and his younger sister was recently diagnosed with an adrenocortical carcinoma. Which underlying genetic mutation is most likely present in this patient?

. RB1 gene mutation
. TP53 gene mutation
. EXT1 gene mutation
. GNAS gene mutation
. NF1 gene mutation

Correct Answer & Explanation

. TP53 gene mutation

Explanation

The strong family history of early-onset breast cancer, adrenocortical carcinoma, and osteosarcoma is the hallmark of Li-Fraumeni syndrome. This autosomal dominant cancer predisposition syndrome is caused by a germline mutation in the TP53 tumor suppressor gene.

Question 5706

Topic: 10. Pathology and Oncology

A 15-year-old male presents with worsening nocturnal distal femur pain. Imaging reveals an aggressive metaphyseal lesion with a "sunburst" periosteal reaction and Codman's triangle. Which genetic mutation profile is most strongly associated with this primary bone tumor?

. t(11;22) chromosomal translocation
. t(X;18) chromosomal translocation
. Mutation in the EXT1 or EXT2 gene
. Mutation in the p53 and/or RB1 tumor suppressor genes
. GNAS1 somatic mutation

Correct Answer & Explanation

. Mutation in the p53 and/or RB1 tumor suppressor genes

Explanation

The clinical and radiographic picture represents classic osteosarcoma. Osteosarcomas are closely linked to mutations in tumor suppressor genes, particularly p53 (as seen in Li-Fraumeni syndrome) and RB1 (hereditary retinoblastoma).

Question 5707

Topic: Bone Tumors

A 65-year-old patient undergoes a workup for pathological vertebral compression fractures, anemia, and hypercalcemia. Radiographs show multiple punched-out lytic lesions in the calvarium. Which laboratory test is the most diagnostic for this suspected malignancy?

. Elevated serum alkaline phosphatase
. Elevated prostate-specific antigen
. Monoclonal spike on serum protein electrophoresis (SPEP)
. Decreased serum parathyroid hormone
. Elevated serum phosphorus

Correct Answer & Explanation

. Monoclonal spike on serum protein electrophoresis (SPEP)

Explanation

Multiple myeloma is the most common primary bone malignancy in adults. It is definitively diagnosed by the presence of a monoclonal spike (M-spike) on SPEP or UPEP, which represents the overproduction of abnormal immunoglobulins by clonal plasma cells.

Question 5708

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain. Radiographs reveal a mixed lytic/sclerotic lesion in the distal femoral metaphysis with a periosteal reaction ('sunburst' pattern). A biopsy confirms high-grade osteosarcoma. What is the standard of care for treatment?

. Wide surgical excision alone
. Neoadjuvant chemotherapy, wide surgical excision, and adjuvant chemotherapy
. Radiation therapy followed by surgical excision
. Amputation without systemic therapy
. Intralesional curettage, bone grafting, and adjuvant chemotherapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical excision, and adjuvant chemotherapy

Explanation

The standard treatment for high-grade intramedullary osteosarcoma includes neoadjuvant (preoperative) chemotherapy, followed by wide surgical resection (limb salvage or amputation), and then adjuvant (postoperative) chemotherapy. Radiation is generally ineffective for primary control of osteosarcoma.

Question 5709

Topic: 10. Pathology and Oncology

Osteoid osteoma and osteoblastoma are both benign bone forming tumors. Which of the following is the most reliable distinguishing feature between an osteoblastoma and an osteoid osteoma?

. Presence of an interconnected network of woven bone trabeculae
. Size of the nidus
. Presence of prominent osteoblasts
. Anatomic location within the vertebral body versus posterior elements
. Presence of malignant degeneration

Correct Answer & Explanation

. Size of the nidus

Explanation

Osteoid osteoma and osteoblastoma are histologically identical, both demonstrating an interconnected network of woven bone trabeculae lined by prominent osteoblasts. The primary distinguishing feature is the size of the nidus: osteoid osteomas are less than 1.5 to 2 cm, whereas osteoblastomas are greater than 2 cm. Osteoblastomas also typically do not produce the classic nocturnal pain relieved by NSAIDs seen in osteoid osteomas.

Question 5710

Topic: 10. Pathology and Oncology

A 14-year-old male presents with a permeative destructive lesion in the diaphysis of his femur with an associated 'onion skin' periosteal reaction. Biopsy confirms Ewing sarcoma. Which chromosomal translocation is pathognomonic for the most common variant of this disease?

. 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 classically associated with the t(11;22)(q24;q12) translocation, which creates the EWS-FLI1 fusion protein (present in about 85-90% of cases). t(9;22) is seen in CML and sometimes chondrosarcoma/myxoid liposarcoma variants, t(X;18) in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 5711

Topic: 10. Pathology and Oncology

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

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical picture describes Ewing sarcoma, which is classically associated with the t(11;22) chromosomal translocation. This specific translocation results in the formation of the EWS-FLI1 fusion protein.

Question 5712

Topic: 10. Pathology and Oncology

According to Mirels' criteria for impending pathologic fractures, which of the following characteristics scores the maximum points (3 points) in its respective category?

. Upper extremity location
. Blastic lesion
. Lesion size < 1/3 of the bone diameter
. Functional pain with weight-bearing
. Avulsion fracture

Correct Answer & Explanation

. Functional pain with weight-bearing

Explanation

Mirels' criteria assess site, pain, lesion type, and size to predict pathologic fracture risk. Functional pain (pain with weight-bearing) scores 3 points, predicting a higher risk of fracture requiring prophylactic fixation.

Question 5713

Topic: 10. Pathology and Oncology

A 20-year-old male complains of deep thigh pain that is distinctly worse at night and dramatically relieved by NSAIDs. Imaging shows a 1 cm radiolucent nidus surrounded by sclerotic bone. What is the central nidus predominantly composed of?

. Hyaline cartilage with endochondral ossification
. Highly vascularized woven bone and osteoblasts
. Multinucleated giant cells in a mononuclear background
. Acellular fibrous tissue with calcifications
. Malignant spindle cells producing osteoid

Correct Answer & Explanation

. Highly vascularized woven bone and osteoblasts

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. The nidus consists of highly vascularized woven bone, active osteoblasts, and unmineralized osteoid, which secretes high levels of prostaglandins.

Question 5714

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with night pain in his left thigh. Radiographs show a permeative diaphyseal lesion with a lamellated periosteal reaction. Biopsy reveals small round blue cells. Which chromosomal translocation is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common chromosomal abnormality is t(11;22), resulting in the EWS-FLI1 fusion protein.

Question 5715

Topic: 10. Pathology and Oncology

A 16-year-old male is diagnosed with conventional osteosarcoma of the distal femur. Molecular analysis of the tumor is most likely to reveal mutations in which of the following tumor suppressor genes?

. BRCA1 and BRCA2
. p53 and Rb
. APC and MLH1
. PTEN and VHL
. MYC and ERG

Correct Answer & Explanation

. p53 and Rb

Explanation

Osteosarcoma is strongly associated with mutations in the Rb (retinoblastoma) and p53 (Li-Fraumeni syndrome) tumor suppressor genes. Loss of heterozygosity at these loci leads to unregulated cell proliferation.

Question 5716

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a permeative lytic lesion in the diaphysis of the femur with an associated "onion-skin" periosteal reaction. A biopsy is planned. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma classically presents in the diaphysis of long bones with an "onion-skin" periosteal reaction. It is characterized by the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein.

Question 5717

Topic: 10. Pathology and Oncology
A 16-year-old boy undergoes a distal femoral resection for a high-grade osteosarcoma following 10 weeks of neoadjuvant chemotherapy. According to the Rosen and Huvos grading system, which of the following histologic findings in the resected specimen is the strongest predictor of long-term survival?
. Negative surgical margins > 2 cm
. Tumor volume < 200 cm3
. Absence of skip metastases in the proximal femur
. Percentage of tumor necrosis > 90%
. High lymphocytic infiltration at the tumor periphery

Correct Answer & Explanation

. Percentage of tumor necrosis > 90%

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the single most important prognostic factor for conventional high-grade osteosarcoma. A 'good response' is defined as > 90% tumor necrosis (Huvos grades III and IV) and correlates strongly with improved disease-free and overall survival rates.

Question 5718

Topic: 10. Pathology and Oncology

A 65-year-old male with long-standing polyostotic Paget's disease presents with a new, rapidly enlarging, painful mass in his proximal femur. Radiographs show a destructive lytic lesion. What is the most likely pathological diagnosis?

. Chondrosarcoma
. Secondary Osteosarcoma
. Multiple Myeloma
. Ewing Sarcoma
. Metastatic Prostate Cancer

Correct Answer & Explanation

. Secondary Osteosarcoma

Explanation

The most common and dreaded complication of Paget's disease is malignant transformation, predominantly into secondary osteosarcoma. It typically presents with new-onset severe pain and a destructive lesion in an older patient.

Question 5719

Topic: Bone Tumors

Multiple Hereditary Exostoses (MHE) is an autosomal dominant condition characterized by multiple osteochondromas. This disorder is most commonly associated with a loss-of-function mutation in genes responsible for the synthesis of:

. Type II collagen
. Heparan sulfate
. Fibroblast growth factor receptor 3
. Cartilage oligomeric matrix protein
. Core binding factor alpha-1

Correct Answer & Explanation

. Heparan sulfate

Explanation

MHE is caused by mutations in the EXT1 or EXT2 genes, which encode glycosyltransferases essential for the synthesis of heparan sulfate. Reduced heparan sulfate disrupts chondrocyte regulation at the growth plate, leading to osteochondroma formation.

Question 5720

Topic: 10. Pathology and Oncology

The "fallen leaf" or "fallen fragment" sign seen on plain radiographs is considered pathognomonic for which of the following benign bone lesions?

. Aneurysmal bone cyst
. Unicameral bone cyst
. Non-ossifying fibroma
. Chondromyxoid fibroma
. Osteoid osteoma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

The 'fallen leaf' sign occurs when a cortical fragment breaks off and falls into the fluid-filled cavity of a Unicameral (simple) bone cyst. This differentiates it from solid tumors where fragments would not sink.

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