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10. Pathology and Oncology MCQs

Practice Set 17 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 321

Topic: Bone Tumors

Which of the following clinical or radiographic features most reliably differentiates an osteoblastoma from an osteoid osteoma?

. Presence of a radiolucent nidus
. Dramatic response to nonsteroidal anti-inflammatory drugs (NSAIDs)
. Size greater than 2 cm in diameter with progressive pain
. Predilection for the diaphyseal cortex of long bones
. Production of abundant woven bone on histology

Correct Answer & Explanation

. Size greater than 2 cm in diameter with progressive pain

Explanation

Osteoblastomas are typically larger than 2 cm and lack the dramatic pain relief with NSAIDs seen in osteoid osteomas. Osteoid osteomas classically present with night pain relieved by NSAIDs and a nidus less than 1.5 to 2 cm.

Question 322

Topic: 10. Pathology and Oncology

A patient with multiple hereditary exostoses (MHE) undergoes genetic testing. The most common mutated genes in this condition are directly responsible for the synthesis of which of the following?

. Type I collagen
. Heparan sulfate
. Fibroblast growth factor receptor
. Parathyroid hormone-related protein (PTHrP)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Heparan sulfate

Explanation

MHE is associated with mutations in the EXT1 and EXT2 genes, which are tumor suppressors involved in the biosynthesis of heparan sulfate. Decreased heparan sulfate alters normal chondrocyte signaling, leading to osteochondroma formation.

Question 323

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with a solitary lytic lesion of the skull. Biopsy reveals histiocytes with folded nuclei and numerous eosinophils. Electron microscopy would most likely reveal which of the following structures?

. Weibel-Palade bodies
. Birbeck granules
. Cowdry A inclusions
. Russell bodies
. Call-Exner bodies

Correct Answer & Explanation

. Birbeck granules

Explanation

The diagnosis is Langerhans cell histiocytosis (eosinophilic granuloma). The pathognomonic electron microscopy finding is Birbeck granules, which have a characteristic "tennis racket" appearance.

Question 324

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, multi-loculated lytic lesion in the anterior cortex of the tibial diaphysis. Histological examination shows islands of epithelial cells in a fibrous stroma. Immunohistochemistry will likely be positive for which of the following markers?

. S-100
. Vimentin
. Cytokeratin
. Desmin
. CD99

Correct Answer & Explanation

. Cytokeratin

Explanation

Adamantinoma is a low-grade malignant bone tumor that almost exclusively occurs in the tibial diaphysis. It is characterized by a biphasic histological pattern of epithelial cells (which stain strongly positive for cytokeratin) within an osteofibrous stroma.

Question 325

Topic: 10. Pathology and Oncology

In a patient newly diagnosed with Ewing sarcoma of the femur, which of the following factors is associated with the worst overall prognosis?

. Distal femur location
. Tumor volume of 50 mL
. Presence of isolated lung metastases
. Presence of bone marrow metastases
. Age younger than 10 years

Correct Answer & Explanation

. Presence of bone marrow metastases

Explanation

The most significant adverse prognostic factor in Ewing sarcoma is the presence of distant metastases at presentation. Specifically, bone or bone marrow metastases confer a significantly worse prognosis than isolated lung metastases.

Question 326

Topic: 10. Pathology and Oncology

A 60-year-old man presents with bowel and bladder dysfunction. Imaging reveals a destructive midline sacral mass. Biopsy demonstrates physaliferous cells. This tumor originates from remnants of which of the following embryonic structures?

. Neural crest
. Notochord
. Paraxial mesoderm
. Endoderm
. Splanchnic mesoderm

Correct Answer & Explanation

. Notochord

Explanation

Chordomas are rare, slow-growing, locally aggressive neoplasms that arise from remnants of the embryonic notochord. They typically occur in the sacrum or clivus and are characterized histologically by vacuolated physaliferous cells.

Question 327

Topic: 10. Pathology and Oncology

Which of the following radiographic findings is most suggestive of the malignant transformation of an enchondroma to a secondary chondrosarcoma?

. Intralesional punctate calcifications
. Endosteal scalloping of less than one-third of cortical thickness
. New onset of deep cortical scalloping and a soft tissue mass
. Central diaphyseal location in the proximal phalanx
. A uniform sclerotic rim surrounding the lesion

Correct Answer & Explanation

. New onset of deep cortical scalloping and a soft tissue mass

Explanation

Signs of malignant transformation of an enchondroma to a chondrosarcoma include new onset of pain, cortical destruction, deep endosteal scalloping (greater than two-thirds of the cortex), and the presence of a soft tissue mass. Enchondromas typically have benign intralesional calcifications and only minor scalloping.

Question 328

Topic: 10. Pathology and Oncology
Following neoadjuvant chemotherapy and surgical resection for conventional osteosarcoma, a patient's tumor specimen is evaluated for histologic necrosis. According to the Huvos grading system, a "good response" indicating improved survival is defined by at least what percentage of tumor necrosis?
. 50%
. 75%
. 90%
. 95%
. 99%

Correct Answer & Explanation

. 90%

Explanation

A good histologic response to neoadjuvant chemotherapy in osteosarcoma is generally defined as greater than or equal to 90% tumor necrosis (Huvos Grade III or IV). This degree of necrosis is the single most important prognostic factor for long-term survival.

Question 329

Topic: Bone Tumors

A 15-year-old girl is found to have multiple enchondromas localized primarily to one side of her body, alongside multiple soft tissue hemangiomas. Which of the following complications is she at the highest risk for compared to a patient with multiple enchondromas alone?

. Pathologic fracture of the femur
. Development of visceral malignancies
. Premature physeal closure
. Development of secondary chondrosarcoma
. Transformation to osteosarcoma

Correct Answer & Explanation

. Development of visceral malignancies

Explanation

The presentation describes Maffucci syndrome, distinguished from Ollier disease by the presence of soft tissue hemangiomas. Patients with Maffucci syndrome have a significantly higher risk of developing concurrent visceral malignancies (e.g., astrocytoma, GI tract) in addition to their chondrosarcoma risk.

Question 330

Topic: 10. Pathology and Oncology

A 30-year-old woman presents with a slow-growing, hard mass on the posterior aspect of the distal femur. Radiographs show a heavily ossified, broad-based mass attached to the cortex. Histology shows low-grade spindle cells and woven bone. What is the most characteristic genetic alteration in this tumor?

. MDM2/CDK4 amplification
. t(11;22) translocation
. GNAS1 mutation
. EXT1 mutation
. p53 deletion

Correct Answer & Explanation

. MDM2/CDK4 amplification

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma typically arising on the posterior distal femur. It is characterized molecularly by supernumerary ring chromosomes leading to the amplification of the MDM2 and CDK4 genes.

Question 331

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a painless soft tissue mass near the knee joint. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Cytogenetic testing confirms a t(X;18)(p11;q11) translocation. This translocation results in which of the following fusion genes?

. EWS-FLI1
. SYT-SSX
. PAX3-FOXO1
. TLS-CHOP
. MYC-IGH

Correct Answer & Explanation

. SYT-SSX

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which fuses the SYT gene on chromosome 18 with one of the SSX genes on the X chromosome. The resulting SYT-SSX fusion protein acts as an aberrant transcriptional regulator.

Question 332

Topic: Bone Tumors

Which of the following factors has proven to increase the risk of degenerative disease of the wrist in patients with multiple hereditary osteochondromas:

. Ulnar negative variance of 5 mm
. Ulnar negative variance of 10 mm
. Distal radial articular slope larger than 25°
. Subluxation of the radial head
. None of the above

Correct Answer & Explanation

. None of the above

Explanation

The above findings are all more common in the forearms and wrists of patients with multiple hereditary exostoses than in the general population. However, there is no parameter shown to increase the risk of degenerative wrist disease.

Question 333

Topic: Bone Tumors

Which of the following bone lesions is shown to improve radiographically and clinically by use of systemic medication:

. Aneurysmal bone cyst
. Unicameral bone cyst
. Multiple exostoses
. Fibrous dysplasia
. Fibrous cortical defect

Correct Answer & Explanation

. Fibrous dysplasia

Explanation

In patients with polyostotic fibrous dysplasia, there is a decrease in pain and fracture rate and an improvement in radiodensity through the use of bisphosphonates. None of the other lesions mentioned respond radiographically to systemic medication.

Question 334

Topic: 10. Pathology and Oncology

A 17-year-old girl is newly diagnosed with an expansile lesion of the distal tibia that is causing pain. Radiographs and biopsy are consistent with an aneurysmal bone cyst. Recommended treatment includes:

. Intralesional steroid injection
. Intralesional bone marrow injection
. Curettage and bone graft
. Wide resection distal tibial osteoarticular allograft
. Local radiation

Correct Answer & Explanation

. Curettage and bone graft

Explanation

Aneurysmal bone cyst is a progressively expansile lesion that does not involute with time. Treatment of aneurysmal bone cysts is curettage and bone graft. Wide resection and structural allografts have a high complication rate and are not indicated for initial treatment. Injection of marrow or steroids is effective for unicameral cysts, but not for aneurysmal cysts. Local radiation is indicated only as an adjunct for lesions that are not surgically resectable.

Question 335

Topic: 10. Pathology and Oncology

A 6-year-old boy has a history of delayed motor milestones and pseudohypertrophy of the calves. He uses his hands to climb up his legs when rising from the floor (Gowers' sign). A muscle biopsy would most likely show an absence of which protein?

. Myosin
. Actin
. Dystrophin
. Laminin alpha-2
. Survival motor neuron (SMN) protein

Correct Answer & Explanation

. Dystrophin

Explanation

The clinical presentation is classic for Duchenne Muscular Dystrophy (DMD). DMD is an X-linked recessive disorder characterized by the absence of the protein dystrophin.

Question 336

Topic: 10. Pathology and Oncology
A 2-year-old child with multiple café-au-lait spots and axillary freckling presents with anterolateral bowing of the tibia. This orthopedic manifestation is notoriously associated with which of the following complications?
. Malignant transformation to osteosarcoma
. Congenital pseudoarthrosis of the tibia
. Overgrowth of the affected limb
. Rapid progression to severe genu valgum
. Ischemic necrosis of the distal tibial epiphysis

Correct Answer & Explanation

. Congenital pseudoarthrosis of the tibia

Explanation

Anterolateral bowing of the tibia is highly associated with Neurofibromatosis Type 1 (NF1) and often progresses to congenital pseudoarthrosis of the tibia. Once fractured, these lesions are notoriously difficult to heal and frequently require complex vascularized grafts or amputation.

Question 337

Topic: 10. Pathology and Oncology

A 54-year-old man with a 40-pack-year smoking history presents to the Respiratory Clinic complaining of a chronic cough and haemoptysis. He has lost 4 kg in weight recently. He has an abnormal chest X-ray, consistent with bronchial carcinoma.

Investigations:

Hb 11.0 g/dl

WCC 6.1 x 109/l

PLT 352 x 109/l

ESR 65 mm in 1 hour

Sodium 132 mmol/l

Potassium 3.9 mmol/l

Creatinine 130 µmol/l Bronchoscopy with transbronchial biopsy reveals adenocarcinoma of the bronchus. You arrange computed tomography of the thorax. Which of the following would tend to rule out the possibility of a surgical cure?

. Forced expiratory volume in 1 s (FEV1) 1.6 l
. Horner syndrome
. Ipsilateral mediastinal lymph node involvement
. Malignant pleural effusion
. Superior vena caval obstruction

Correct Answer & Explanation

. Malignant pleural effusion

Explanation

Correct Answer: D- Malignant pleural effusion Explanation Malignant pleural effusion Pleural effusion implies pleural involvement and this would preclude a surgical cure. Forced expiratory volume in 1 s (FEV1) 1.6 l Forced expiratory volume in 1 s (FEV1) 1.6 l is incorrect. A forced expiratory volume in 1 s (FEV1) of less than 1.5 l precludes surgery for bronchial carcinoma because there is not enough lung reserve. Horner syndrome Horner syndrome is incorrect. Horner syndrome is attributable to local nerve involvement and therefore does not exclude successful surgical excision of the primary tumour. Ipsilateral mediastinal lymph node involvement Ipsilateral mediastinal lymph node involvement is incorrect. Contralateral lymph node involvement implies distant spread and again precludes surgery. Superior vena caval obstruction Superior vena caval obstruction is incorrect. Superior vena caval obstruction is not an absolute contraindication to surgery.

Question 338

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain. Radiographs show a destructive, bone-forming lesion in the distal femoral metaphysis with a periosteal "sunburst" reaction. If a biopsy is planned, which of the following principles must be strictly followed?

. The biopsy tract should be placed transversely across the limb
. A tourniquet should be inflated and exsanguination performed prior to biopsy
. The biopsy tract must be excisable during definitive tumor resection
. Only the soft tissue component should be biopsied
. Hematoma drainage should be encouraged post-operatively

Correct Answer & Explanation

. The biopsy tract must be excisable during definitive tumor resection

Explanation

When performing a biopsy of a suspected primary bone sarcoma, the biopsy tract must be carefully planned so it can be excised en bloc with the tumor during definitive surgery. Transverse incisions and exsanguination are strictly contraindicated.

Question 339

Topic: 10. Pathology and Oncology

A 15-year-old male presents with persistent distal femur pain. Radiographs show a destructive metaphyseal lesion with a 'sunburst' periosteal reaction and Codman's triangle. Biopsy reveals pleomorphic spindle cells producing immature osteoid. What is the most common site of metastasis for this primary tumor?

. Liver
. Brain
. Lungs
. Regional lymph nodes
. Spine

Correct Answer & Explanation

. Lungs

Explanation

The clinical and histologic findings are diagnostic of osteosarcoma. The most common site of metastasis for osteosarcoma is the lungs, followed by other bones.

Question 340

Topic: Bone Tumors

A 14-year-old boy complains of progressive distal thigh pain that awakens him at night. Radiographs reveal a metaphyseal, poorly defined lytic lesion with a 'sunburst' periosteal reaction and Codman's triangle. What is the most likely diagnosis?

. Ewing sarcoma
. Osteosarcoma
. Chondrosarcoma
. Osteoid osteoma
. Multiple myeloma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma typically presents in the metaphysis of long bones (most commonly the distal femur) in adolescents. The 'sunburst' periosteal reaction and Codman's triangle are classic radiographic findings.

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