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10. Pathology and Oncology MCQs

Practice Set 244 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 4861

Topic: Bone Tumors
A 10-year-old girl is found to have a diaphyseal femur fracture after a minor fall. Radiographs show a "shepherd's crook" deformity with an intramedullary "ground-glass" appearance. She also has precocious puberty and large café-au-lait spots. What is the underlying genetic mutation?
. Rb1
. TP53
. GNAS
. FGFR3
. SH3BP2

Correct Answer & Explanation

. GNAS

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, endocrine abnormalities (such as precocious puberty), and "coast of Maine" café-au-lait spots. It is caused by a somatic activating missense mutation in the GNAS gene.

Question 4862

Topic: 10. Pathology and Oncology

A 25-year-old male presents with chronic anterior tibial pain. Radiographs demonstrate a multilocular, eccentric, "soap-bubble" lytic lesion in the anterior diaphysis of the tibia. Biopsy reveals islands of epithelial cells within a dense fibrous stroma. What is the most appropriate management?

. Observation with serial imaging
. Intralesional curettage and bone grafting
. Wide surgical resection and reconstruction
. Neoadjuvant chemotherapy followed by excision
. Primary radiation therapy

Correct Answer & Explanation

. Wide surgical resection and reconstruction

Explanation

Adamantinoma is a rare, low-grade malignant bone tumor that almost exclusively affects the anterior tibial diaphysis. Because it is largely resistant to radiation and chemotherapy, wide surgical resection with reconstruction is the gold standard treatment.

Question 4863

Topic: 10. Pathology and Oncology

A 65-year-old male presents with generalized bone pain and fatigue. Radiographs show multiple "punched-out" lytic lesions in his skull and pelvis. A technetium-99m bone scan shows decreased uptake in these affected areas. Laboratory tests reveal hypercalcemia. What is the most likely diagnosis?

. Metastatic prostate cancer
. Hyperparathyroidism
. Paget disease of bone
. Multiple myeloma
. Metastatic lung cancer

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma classically presents with multiple lytic "punched-out" bone lesions that are "cold" on a technetium bone scan due to a lack of reactive osteoblastic activity. Diagnostic criteria also include hypercalcemia, renal failure, and anemia (CRAB criteria).

Question 4864

Topic: 10. Pathology and Oncology

A 55-year-old male complains of chronic low back pain and recent onset of bowel incontinence. MRI reveals a large destructive mass centered in the sacrum. Biopsy shows lobules of vacuolated cells with a bubbly cytoplasm. From what embryonic structure does this tumor arise?

. Neural crest
. Notochord
. Somites
. Endoderm
. Mesenchyme

Correct Answer & Explanation

. Notochord

Explanation

Chordomas are rare, slow-growing malignant bone tumors that arise from the embryonic remnants of the notochord. They typically occur in the midline of the axial skeleton, most commonly in the sacrum and clivus, and feature pathognomonic "physaliferous" cells.

Question 4865

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with multiple asymmetrical hard lumps on his hands. Exam reveals several bluish soft tissue nodules on his forearm. Radiographs show multiple expansile radiolucent lesions in the phalanges with stippled calcifications. What is this patient at highest risk of developing later in life?

. Osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Leukemia
. Fibrosarcoma

Correct Answer & Explanation

. Chondrosarcoma

Explanation

This presentation is classic for Maffucci syndrome, which is characterized by multiple enchondromas and soft tissue hemangiomas. Patients with Maffucci syndrome have a very high risk of malignant transformation, most commonly to secondary chondrosarcoma.

Question 4866

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a painless, deep intramuscular mass in his thigh. Core biopsy reveals myxoid liposarcoma. Which of the following translocations is most strongly associated with this specific histology?

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

Correct Answer & Explanation

. t(12;16)

Explanation

Myxoid liposarcoma is characterized by the t(12;16)(q13;p11) translocation, which creates the FUS-DDIT3 fusion protein. The presence of a round cell component (>5%) indicates a higher-grade tumor and a significantly worse prognosis.

Question 4867

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a deep, slow-growing mass in the popliteal fossa. Core needle biopsy demonstrates a biphasic tumor consisting of epithelial and spindle cells. Which of the following chromosomal translocations is most characteristic of this diagnosis?

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

Correct Answer & Explanation

. t(X;18)

Explanation

This patient has a synovial sarcoma, which characteristically features the t(X;18)(p11;q11) translocation resulting in the SYT-SSX fusion gene. This molecular marker is present in over 90% of synovial sarcomas.

Question 4868

Topic: 10. Pathology and Oncology

A 15-year-old boy completes neoadjuvant chemotherapy for conventional osteosarcoma of the distal femur and subsequently undergoes wide local excision. Which of the following variables is the most significant prognostic factor for long-term overall survival?

. Initial tumor volume
. Alkaline phosphatase level at diagnosis
. Histologic necrosis greater than 90% in the resected specimen
. Specific anatomic location of the primary tumor
. Presence of a soft tissue extension pre-operatively

Correct Answer & Explanation

. Histologic necrosis greater than 90% in the resected specimen

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the most critical prognostic indicator for overall survival in osteosarcoma. Greater than 90% necrosis indicates a good histologic response and significantly improved prognosis.

Question 4869

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a large, destructive pelvic mass showing 'ring and arc' calcifications on plain radiography. Biopsy confirms a grade II conventional chondrosarcoma. What is the most appropriate management for this patient?

. Neoadjuvant chemotherapy followed by wide resection
. Definitive external beam radiation therapy
. Wide surgical resection alone
. Intralesional curettage, burring, and bone grafting
. Neoadjuvant denosumab therapy followed by resection

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcoma is notoriously resistant to both chemotherapy and radiation therapy. The gold standard treatment for intermediate to high-grade chondrosarcoma of the pelvis is wide surgical resection with negative margins.

Question 4870

Topic: Bone Tumors

An 18-year-old boy complains of nocturnal lower back pain that is completely relieved by ibuprofen. A CT scan reveals a 1 cm sclerotic lesion with a central radiolucent nidus in the L4 pedicle. What is the most appropriate initial minimally invasive treatment?

. Intralesional curettage and bone grafting
. CT-guided radiofrequency ablation
. En bloc spondylectomy
. Selective arterial embolization
. External beam radiation

Correct Answer & Explanation

. CT-guided radiofrequency ablation

Explanation

The clinical presentation and imaging are classic for an osteoid osteoma. CT-guided radiofrequency ablation (RFA) is highly successful, minimally invasive, and is considered the treatment of choice for typical osteoid osteomas.

Question 4871

Topic: 10. Pathology and Oncology

A 55-year-old woman with advanced breast cancer presents with progressively worsening right thigh pain. Radiographs reveal a 3.5 cm lytic lesion in the peritrochanteric region of the right femur, involving 60% of the cortical diameter. Her Mirels' score is 10. What is the most appropriate next step in management?

. Observation and protected weight-bearing
. Intravenous bisphosphonate therapy alone
. Definitive external beam radiation alone
. Prophylactic cephalomedullary nailing followed by radiation
. Core biopsy and immediate neoadjuvant chemotherapy

Correct Answer & Explanation

. Prophylactic cephalomedullary nailing followed by radiation

Explanation

A Mirels' score of 9 or greater indicates a high risk for impending pathologic fracture. Prophylactic internal fixation is indicated, followed by post-operative radiation to achieve local tumor control.

Question 4872

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with pain and swelling of her left knee. MRI demonstrates an expansile, eccentric lytic lesion in the distal femur metaphysis containing multiple fluid-fluid levels. Genetic analysis of this lesion would most likely reveal which of the following alterations?

. USP6 (t(16;17)) rearrangement
. GNAS mutation
. EXT1 mutation
. EWSR1-FLI1 (t(11;22)) translocation
. MDM2 amplification

Correct Answer & Explanation

. USP6 (t(16;17)) rearrangement

Explanation

The clinical and MRI findings (fluid-fluid levels) are diagnostic of an aneurysmal bone cyst (ABC). Primary ABCs are true neoplasms driven by a USP6 rearrangement, most commonly t(16;17).

Question 4873

Topic: Bone Tumors

A 9-year-old boy experiences acute right shoulder pain after a minor fall. X-rays show a central, purely lytic lesion in the proximal humerus metaphysis extending to the physis, with a small piece of cortical bone resting at the dependent portion of the cyst. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Osteosarcoma
. Non-ossifying fibroma
. Unicameral bone cyst
. Eosinophilic granuloma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

A central, lytic metaphyseal lesion in a child with a 'fallen leaf' sign (a fragment of fractured cortex at the bottom of the cyst) is pathognomonic for a fractured unicameral bone cyst (UBC).

Question 4874

Topic: 10. Pathology and Oncology

A 30-year-old woman undergoes excision of a slow-growing, deep mass in the plantar aspect of her foot. Histology demonstrates fascicles of uniform spindle cells with clear cytoplasm. Immunohistochemistry is strongly positive for S-100 and HMB-45. What is the most likely diagnosis?

. Synovial sarcoma
. Clear cell sarcoma
. Epithelioid sarcoma
. Myxoid liposarcoma
. Alveolar soft part sarcoma

Correct Answer & Explanation

. Clear cell sarcoma

Explanation

Clear cell sarcoma (melanoma of soft parts) typically arises in the deep soft tissues of the foot and ankle in young adults. It shows melanocytic differentiation and stains positive for S-100 and HMB-45, distinguishing it from synovial sarcoma.

Question 4875

Topic: 10. Pathology and Oncology

A 50-year-old man requires surgical resection and radiation therapy for a high-grade soft tissue sarcoma of the anterior thigh. When counseling the patient, you explain that preoperative radiation therapy, compared to postoperative radiation therapy, carries a significantly higher risk of which complication?

. Long-term limb edema
. Major wound healing complications
. Local tumor recurrence
. Deep vein thrombosis
. Permanent joint stiffness

Correct Answer & Explanation

. Major wound healing complications

Explanation

Preoperative radiation therapy for soft tissue sarcomas is associated with a significantly higher rate of major acute wound healing complications (approx. 35%). However, it results in less long-term fibrosis, stiffness, and edema compared to postoperative radiation.

Question 4876

Topic: Bone Tumors

A 35-year-old woman with an unresectable giant cell tumor of the sacrum is initiated on denosumab therapy. Which of the following best describes the expected histologic and radiographic response to this medication?

. Cystic degeneration with the development of prominent fluid-fluid levels
. Intense peripheral rim enhancement with central liquefactive necrosis
. Depletion of multinucleated giant cells and replacement with dense osteosclerosis
. Massive intralesional hemorrhage mimicking an aneurysmal bone cyst
. Rapid dedifferentiation into a high-grade osteosarcoma

Correct Answer & Explanation

. Depletion of multinucleated giant cells and replacement with dense osteosclerosis

Explanation

Denosumab is a RANKL inhibitor that prevents the maturation of osteoclast-like giant cells. Treatment results in the rapid depletion of giant cells and the laying down of woven bone, appearing as dense central osteosclerosis on radiographs.

Question 4877

Topic: Bone Tumors
A 10-year-old girl is evaluated for a limp. Radiographs demonstrate a 'ground-glass' expansile lesion with a 'shepherd's crook' deformity in the proximal femur. Physical exam reveals unilateral café-au-lait spots with irregular 'coast of Maine' borders. This syndrome is caused by a post-zygotic mutation in which gene?
. EXT1
. NF1
. GNAS
. RB1
. TP53

Correct Answer & Explanation

. GNAS

Explanation

This patient has McCune-Albright syndrome, featuring polyostotic fibrous dysplasia, café-au-lait spots, and precocious puberty. It is caused by an activating missense mutation in the GNAS gene, which encodes the alpha subunit of the Gs protein.

Question 4878

Topic: 10. Pathology and Oncology

A 45-year-old man has a biopsy-proven myxoid liposarcoma of the left thigh. During the staging workup, in addition to evaluating the lungs, which anatomic area must be meticulously imaged due to this tumor's unique pattern of extrapulmonary metastasis?

. Brain parenchyma
. Liver
. Axial skeleton
. Regional lymph nodes
. Contralateral lower extremity

Correct Answer & Explanation

. Axial skeleton

Explanation

Myxoid liposarcoma has a distinct propensity to metastasize to extrapulmonary bone sites, particularly the spine. Whole-body MRI or a targeted MRI of the entire spine is recommended during the initial staging workup.

Question 4879

Topic: 10. Pathology and Oncology

A 25-year-old woman presents with a slow-growing, painless mass on the posterior distal femur. Radiographs reveal a densely ossified mass arising from the cortex with a radiolucent cleft separating the tumor from the underlying bone. What molecular alteration is highly specific to this tumor?

. MDM2 and CDK4 amplification
. EWSR1 translocation
. H3F3A mutation
. USP6 rearrangement
. EXT1 deletion

Correct Answer & Explanation

. MDM2 and CDK4 amplification

Explanation

The clinical and radiographic presentation ('string sign' or radiolucent cleft) is classic for parosteal osteosarcoma. This low-grade surface osteosarcoma is driven by the amplification of MDM2 and CDK4 on chromosome 12q13-15.

Question 4880

Topic: 10. Pathology and Oncology

A 42-year-old man is found to have an incidental cartilaginous lesion in the proximal humerus diaphysis. Which of the following radiographic features is the most reliable indicator of malignant transformation to a secondary chondrosarcoma?

. Intralesional 'pop-corn' calcification
. Endosteal scalloping involving greater than two-thirds of the cortical thickness
. Lesion size of exactly 2 centimeters
. Location in the diaphysis rather than the metaphysis
. A well-defined sclerotic margin without periosteal reaction

Correct Answer & Explanation

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

Explanation

Differentiating an enchondroma from a low-grade chondrosarcoma relies heavily on radiographic features. Deep endosteal scalloping (more than 2/3 of the cortical thickness), cortical thickening, or cortical breakthrough are highly indicative of chondrosarcoma.

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