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10. Pathology and Oncology MCQs

Practice Set 195 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 3881

Topic: Bone Tumors

A 15-year-old male presents with a symptomatic surface lesion on his proximal humerus.

Imaging displays a 2 cm lesion causing saucerization of the outer cortex, with an intact sclerotic rim and without medullary extension. Which feature most reliably differentiates this lesion from a periosteal osteosarcoma?

. Saucerization of the underlying cortex
. Intact sclerotic cortical margin without true medullary extension
. Presence of a 'sunburst' periosteal reaction
. Location in the metaphysis rather than the diaphysis
. Size greater than 5 cm

Correct Answer & Explanation

. Saucerization of the underlying cortex

Explanation

Periosteal chondromas typically cause a well-defined saucerization of the outer cortex with a thick sclerotic rim and do not invade the medullary canal. Periosteal osteosarcoma tends to be larger, lacks a well-defined sclerotic rim, and often exhibits aggressive periosteal reactions.

Question 3882

Topic: 10. Pathology and Oncology

A 25-year-old female presents with severe asymmetric limb deformity and multiple bluish subcutaneous nodules. Radiographs reveal multiple expansile cartilaginous lesions in the phalanges and long bones. Which of the following is true regarding this patient's condition compared to Ollier disease?

. It has a lower risk of malignant transformation
. It is inherited in an autosomal dominant pattern
. It is associated with a higher risk of extraskeletal and visceral malignancies
. It is caused by a germline mutation in the EXT1 gene
. It typically presents with bilateral, highly symmetric involvement

Correct Answer & Explanation

. It is associated with a higher risk of extraskeletal and visceral malignancies

Explanation

The patient has Maffucci syndrome, characterized by multiple enchondromas and soft-tissue venous malformations (hemangiomas). Compared to Ollier disease, Maffucci syndrome carries a significantly higher risk of extraskeletal malignancies, including astrocytomas, GI tumors, and angiosarcomas.

Question 3883

Topic: 10. Pathology and Oncology

A 22-year-old male presents with a slow-growing, painless mass on his proximal humerus. Radiographs demonstrate the surface lesion shown below, measuring 2.5 cm with underlying cortical saucerization.

Biopsy reveals hypercellular cartilage with no cytological atypia or host bone permeation. What is the recommended definitive treatment?

. Wide en bloc resection with 2 cm margins
. Neoadjuvant chemotherapy followed by limb salvage
. Intralesional curettage and burring
. Marginal excision including the underlying sclerotic cortex
. Observation with serial MRI scans

Correct Answer & Explanation

. Marginal excision including the underlying sclerotic cortex

Explanation

The image and clinical presentation describe a periosteal (juxtacortical) chondroma, a benign surface cartilage tumor. The treatment of choice for symptomatic lesions is marginal excision en bloc with the underlying sclerotic bone to minimize the risk of recurrence.

Question 3884

Topic: 10. Pathology and Oncology

A 45-year-old male complains of new-onset, deep aching pain in his right shoulder, primarily occurring at rest and at night. Radiographs demonstrate a 6 cm cartilaginous intramedullary lesion in the proximal humerus. Which of the following radiographic features most strongly differentiates a secondary low-grade chondrosarcoma from a benign enchondroma?

. Popcorn-like stippled calcifications
. Endosteal scalloping greater than two-thirds of the cortical thickness
. Sclerotic margins surrounding the lesion
. Central location within the diaphyseal medullary canal
. Lesion size measuring between 3 to 5 cm

Correct Answer & Explanation

. Endosteal scalloping greater than two-thirds of the cortical thickness

Explanation

While both enchondromas and low-grade chondrosarcomas share stippled calcifications, endosteal scalloping involving greater than 2/3 of the cortical thickness, cortical breakthrough, and the presence of rest pain strongly indicate malignant transformation to a chondrosarcoma.

Question 3885

Topic: 10. Pathology and Oncology

A 40-year-old male presents with chronic hip pain. Radiographs reveal a purely lytic, slightly expansile lesion in the femoral head epiphysis extending to the articular surface. Biopsy demonstrates cells with abundant clear cytoplasm, distinct cell membranes, and interspersed areas of hyaline cartilage. What is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Giant cell tumor of bone
. Osteoblastoma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a low-grade malignant cartilage tumor that characteristically arises in the epiphysis of long bones in adults aged 30-50. It must be histologically and clinically distinguished from chondroblastoma, which typically occurs in pediatric patients with open physes.

Question 3886

Topic: 10. Pathology and Oncology

Somatic mosaic mutations in the IDH1 or IDH2 (isocitrate dehydrogenase) genes are most frequently associated with the pathogenesis of which of the following pairs of conditions?

. Osteochondroma and Multiple Hereditary Exostoses
. Enchondroma and Ollier disease
. Periosteal chondroma and Chondromyxoid fibroma
. Chondroblastoma and Clear cell chondrosarcoma
. Non-ossifying fibroma and Jaffe-Campanacci syndrome

Correct Answer & Explanation

. Enchondroma and Ollier disease

Explanation

Mutations in the IDH1 and IDH2 genes are strongly linked to the development of central cartilaginous tumors. These somatic mutations are found in a majority of solitary enchondromas, as well as in patients with Ollier disease and Maffucci syndrome.

Question 3887

Topic: 10. Pathology and Oncology

A 45-year-old male presents with night pain, particularly in the midshaft of his femur, which is relieved by aspirin. Radiographs show a small lucent nidus surrounded by reactive sclerosis. What is the most likely diagnosis?

. Osteosarcoma
. Ewing sarcoma
. Osteoid osteoma
. Chondrosarcoma
. Fibrous dysplasia

Correct Answer & Explanation

. Osteoid osteoma

Explanation

The classic presentation of an osteoid osteoma includes nocturnal pain, often worse at night, which is characteristically relieved by NSAIDs (like aspirin) due to its prostaglandin-mediated pain. Radiographically, it presents as a small lucent nidus (typically <1.5 cm) surrounded by a zone of reactive sclerosis. Osteosarcoma and Ewing sarcoma are malignant and would not typically be relieved by aspirin in this manner. Chondrosarcoma is a cartilaginous tumor. Fibrous dysplasia has a different radiographic appearance and pain pattern.

Question 3888

Topic: Bone Tumors

Which of the following describes the characteristic radiographic appearance of a unicameral bone cyst (UBC)?

. Sunburst periosteal reaction with Codman's triangle
. Ground-glass appearance with shepherd's crook deformity
. Eccentric lytic lesion with cortical destruction
. Metaphyseal lesion with 'fallen leaf' sign
. Onion-skin periosteal reaction

Correct Answer & Explanation

. Metaphyseal lesion with 'fallen leaf' sign

Explanation

A unicameral bone cyst (UBC), or simple bone cyst, is typically a metaphyseal lesion (often proximal humerus or femur) that appears as a well-circumscribed, lytic lesion. The 'fallen leaf' sign refers to a fragment of cortical bone that has fractured off and fallen into the fluid-filled cavity of the cyst, indicating a pathologic fracture through the cyst. Sunburst reaction and Codman's triangle are associated with osteosarcoma. Ground-glass appearance with shepherd's crook deformity is characteristic of fibrous dysplasia. Eccentric lytic lesion with cortical destruction is more indicative of aggressive tumors like osteosarcoma or giant cell tumor. Onion-skin reaction is seen in Ewing sarcoma.

Question 3889

Topic: 10. Pathology and Oncology

What is the most common primary malignant bone tumor in children and adolescents?

. Chondrosarcoma
. Fibrosarcoma
. Ewing sarcoma
. Osteosarcoma
. Multiple myeloma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, typically presenting in the metaphysis of long bones (e.g., distal femur, proximal tibia, proximal humerus). Ewing sarcoma is the second most common, often affecting the diaphysis of long bones and flat bones. Chondrosarcoma and fibrosarcoma are less common in this age group, and multiple myeloma is a malignancy of plasma cells typically seen in older adults.

Question 3890

Topic: 10. Pathology and Oncology

Which of the following is the most common primary benign bone tumor?

. Osteosarcoma
. Enchondroma
. Osteochondroma
. Giant cell tumor
. Aneurysmal bone cyst

Correct Answer & Explanation

. Osteochondroma

Explanation

Osteochondroma (exostosis) is the most common primary benign bone tumor. It is a cartilage-capped bony projection on the external surface of bone, arising from the metaphysis. Enchondroma is common but less frequent than osteochondroma. Osteosarcoma is malignant. Giant cell tumors and aneurysmal bone cysts are less common benign tumors.

Question 3891

Topic: Bone Tumors

Which of the following describes the characteristic radiographic appearance of fibrous dysplasia?

. Sunburst periosteal reaction with Codman's triangle
. Ground-glass appearance with shepherd's crook deformity
. Onion-skin periosteal reaction
. Lytic lesion with a 'soap bubble' appearance
. Dense sclerosis with a central nidus

Correct Answer & Explanation

. Ground-glass appearance with shepherd's crook deformity

Explanation

Fibrous dysplasia is characterized by a 'ground-glass' appearance on radiographs due to immature woven bone within a fibrous stroma. When affecting the proximal femur, severe forms can lead to bowing and deformity known as a 'shepherd's crook deformity.' Sunburst reaction is osteosarcoma. Onion-skin reaction is Ewing sarcoma. Lytic lesions with 'soap bubble' appearance can be seen in aneurysmal bone cysts or giant cell tumors. Dense sclerosis with a central nidus is characteristic of osteoid osteoma.

Question 3892

Topic: 10. Pathology and Oncology

A 16-year-old male presents with localized knee pain, worse at night and relieved by aspirin. Radiographs show a small lucent lesion with a central nidus and surrounding sclerotic bone in the proximal tibia. What is the MOST likely diagnosis?

. Osteochondroma
. Enchondroma
. Osteosarcoma
. Osteoid osteoma
. Ewing's sarcoma

Correct Answer & Explanation

. Osteoid osteoma

Explanation

The classic clinical presentation of localized pain, worse at night, relieved by aspirin, combined with the radiographic finding of a small lucent lesion with a central nidus and surrounding reactive sclerosis, is pathognomonic for an Osteoid Osteoma. Osteochondroma is an exostosis. Enchondroma is a lucent lesion often in the hand/foot. Osteosarcoma and Ewing's sarcoma are malignant and present differently, without the typical aspirin relief.

Question 3893

Topic: 10. Pathology and Oncology

A 16-year-old male presents with progressively worsening knee pain and swelling. Radiographs show a destructive lesion in the distal femur with a "sunburst" periosteal reaction and Codman's triangle. What is the MOST likely diagnosis?

. Ewing's sarcoma
. Chondrosarcoma
. Osteosarcoma
. Fibrous dysplasia
. Enchondroma

Correct Answer & Explanation

. Osteosarcoma

Explanation

This classic radiographic presentation of a destructive lesion with "sunburst" periosteal reaction and Codman's triangle in the metaphysis of a long bone (distal femur is common) in an adolescent is highly characteristic of Osteosarcoma, the most common primary malignant bone tumor in this age group. Ewing's sarcoma often has an "onion-skin" reaction and is typically diaphyseal. Chondrosarcoma presents differently. Fibrous dysplasia and enchondroma are benign.

Question 3894

Topic: 10. Pathology and Oncology

Which of the following factors is considered the MOST significant determinant of prognosis in patients with osteosarcoma?

. Patient age at diagnosis
. Location of the primary tumor
. Size of the primary tumor
. Presence of metastatic disease at presentation
. Response to neoadjuvant chemotherapy

Correct Answer & Explanation

. Presence of metastatic disease at presentation

Explanation

The presence of metastatic disease at presentation is by far the MOST significant determinant of prognosis in patients with osteosarcoma. Patients with metastatic disease have a significantly worse prognosis than those with localized disease. While tumor size, location, and response to chemotherapy are important prognostic indicators for localized disease, metastasis is the overriding factor for overall survival.

Question 3895

Topic: 10. Pathology and Oncology

A 60-year-old male with a history of prostate cancer metastatic to bone presents with new onset lower back pain and bilateral leg weakness. On examination, he has decreased motor strength in both lower extremities (3/5), decreased sensation below T10, and hyperreflexia. What is the most appropriate emergent management?

. High-dose oral corticosteroids and pain management
. Urgent MRI of the spine
. Surgical decompression of the spinal cord
. Radiation therapy to the metastatic lesion
. Physical therapy for strengthening

Correct Answer & Explanation

. High-dose oral corticosteroids and pain management

Explanation

This patient presents with signs and symptoms highly suggestive of impending or established spinal cord compression due to metastatic disease (epidural spinal cord compression - ESCC). The most appropriate emergent step is high-dose intravenous corticosteroids (e.g., dexamethasone) to reduce peritumoral edema and preserve neurological function while further evaluation (urgent MRI) and definitive treatment planning (surgical decompression, radiation therapy) are underway. While an MRI is critical for diagnosis, steroids should not be delayed awaiting imaging if ESCC is suspected. Surgery or radiation are definitive treatments, but steroids buy time and can temporarily improve symptoms.

Question 3896

Topic: Bone Tumors

What is the classic radiographic finding associated with osteosarcoma?

. Punctuated calcifications with a 'ring and arc' pattern
. Expansile lytic lesion with a 'soap bubble' appearance
. Cortical thickening and periosteal reaction with 'onion skin' appearance
. Sunburst periosteal reaction and Codman's triangle
. Geographic lysis with sclerotic border

Correct Answer & Explanation

. Sunburst periosteal reaction and Codman's triangle

Explanation

Osteosarcoma classically presents with aggressive radiographic features, including a 'sunburst' periosteal reaction (spicules of new bone radiating outwards) and Codman's triangle (triangular elevation of the periosteum at the margins of the lesion). These indicate rapid bone formation and destruction. 'Ring and arc' calcifications are characteristic of chondrosarcoma. 'Soap bubble' appearance is often seen in giant cell tumors. 'Onion skin' periosteal reaction is characteristic of Ewing's sarcoma. Geographic lysis with a sclerotic border is more indicative of a benign or slow-growing lesion.

Question 3897

Topic: 10. Pathology and Oncology

What is the most common benign bone tumor?

. Osteoid osteoma
. Enchondroma
. Osteochondroma
. Fibrous dysplasia
. Non-ossifying fibroma

Correct Answer & Explanation

. Osteochondroma

Explanation

Osteochondroma (exostosis) is by far the most common benign bone tumor, accounting for approximately 35-50% of all benign bone tumors. It is characterized by an outgrowth of bone covered by a cartilaginous cap, typically arising from the metaphysis of long bones. While other options are benign bone tumors, they are less common than osteochondromas.

Question 3898

Topic: 10. Pathology and Oncology

A patient undergoing knee arthroscopy develops acute hypertension (BP 180/95 mmHg) and tachycardia (HR 115 bpm) during local anesthetic injection. The patient reports anxiety. What is the most likely cause of this acute hemodynamic change?

. Systemic absorption of local anesthetic with cardiac toxicity
. Venous air embolism
. Pain and anxiety
. Malignant hyperthermia
. Occult hemorrhage

Correct Answer & Explanation

. Pain and anxiety

Explanation

Acute pain and anxiety are very common causes of transient hypertension and tachycardia, especially during procedures where local anesthetics are administered or during surgical stimulation. Systemic absorption of local anesthetic with cardiac toxicity would typically present with more severe arrhythmias, neurological symptoms (seizures, perioral numbness), and often hypotension, not hypertension. Venous air embolism is associated with hypotension and increased ETCO2. Malignant hyperthermia is characterized by hyperthermia, muscle rigidity, and rapidly increasing ETCO2. Occult hemorrhage would lead to hypotension and tachycardia.

Question 3899

Topic: 10. Pathology and Oncology

A 65-year-old male with a history of prostate cancer (diagnosed 5 years ago, currently in remission) presents with new onset, severe lower back pain radiating down his left leg. He denies any recent trauma. On examination, he has tenderness over the L4 spinous process and mild weakness (4/5) in left ankle dorsiflexion. What is the most critical diagnostic test to perform first?

. Plain radiographs of the lumbar spine.
. Electromyography (EMG).
. MRI of the entire spine.
. Bone scan (technetium-99m).
. Lumbar discography.

Correct Answer & Explanation

. MRI of the entire spine.

Explanation

Given the patient's history of prostate cancer, new onset severe back pain, and neurological deficit (even mild), metastatic disease to the spine causing potential cord compression or nerve root involvement must be ruled out urgently. An MRI of the entire spine is the most critical diagnostic test as it can identify metastatic lesions, differentiate them from degenerative changes, and assess for spinal cord compression. Plain radiographs are often normal in early metastatic disease. EMG assesses nerve function but doesn't identify the cause. Bone scan is good for detecting bony metastases but doesn't show soft tissue involvement or cord compression as well as MRI. Lumbar discography is an invasive procedure used for diagnosing discogenic pain and is not appropriate here.

Question 3900

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with a painful swelling over his proximal tibia. He has a low-grade fever and appears unwell. X-rays show periosteal reaction and lucency in the metaphysis of the tibia. Blood tests reveal an elevated ESR and CRP. What is the most likely diagnosis?

. Ewing's sarcoma.
. Osteomyelitis.
. Osteoid osteoma.
. Stress fracture.
. Non-ossifying fibroma.

Correct Answer & Explanation

. Osteomyelitis.

Explanation

The constellation of painful swelling, fever, malaise, elevated inflammatory markers (ESR, CRP), and radiographic findings of periosteal reaction and metaphyseal lucency in a child is highly suggestive of acute osteomyelitis. This is an infection of the bone, most commonly hematogenous in children, affecting the highly vascular metaphysis. Ewing's sarcoma can also present with pain, swelling, and periosteal reaction ('onion skin'), but usually with more aggressive bone destruction and often a soft tissue mass. Osteoid osteoma is a benign bone tumor causing nocturnal pain relieved by NSAIDs, typically without systemic signs. Stress fractures are related to activity and usually lack systemic signs. Non-ossifying fibroma is a benign, often asymptomatic, cortical bone lesion.

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