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10. Pathology and Oncology MCQs

Practice Set 336 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 6701

Topic: 10. Pathology and Oncology

A 35-year-old male presents with chronic hip pain. Radiographs reveal a lytic lesion in the femoral head epiphysis with a sclerotic margin and central calcification. Histology shows cells with abundant clear cytoplasm and distinct cell membranes interspersed with hyaline cartilage. What is the most appropriate definitive surgical treatment?

. Intralesional curettage with bone grafting
. Intralesional curettage with phenol and cement
. Wide local excision/resection
. Adjuvant radiation therapy alone
. Above-knee amputation

Correct Answer & Explanation

. Wide local excision/resection

Explanation

Clear cell chondrosarcoma is a low-grade malignancy that classically occurs in the epiphysis, mimicking benign chondroblastoma. Unlike chondroblastoma, it has a high local recurrence rate with curettage and requires wide local excision.

Question 6702

Topic: 10. Pathology and Oncology

A 60-year-old man presents with severe proximal thigh pain. Radiographs show a large, purely osteolytic, expansile lesion in the proximal femur with an impending subtrochanteric fracture. Biopsy confirms metastatic clear cell renal carcinoma. Before proceeding with prophylactic cephalomedullary nailing, which of the following is highly recommended?

. Preoperative radiation therapy
. Preoperative systemic targeted therapy (e.g., Sunitinib)
. Preoperative angioembolization of the lesion
. Neoadjuvant systemic chemotherapy
. Placement of a temporary external fixator

Correct Answer & Explanation

. Preoperative angioembolization of the lesion

Explanation

Renal cell carcinoma and thyroid carcinoma bone metastases are notoriously hypervascular. Preoperative angioembolization is strongly recommended 24 to 48 hours prior to surgery to minimize catastrophic intraoperative hemorrhage.

Question 6703

Topic: 10. Pathology and Oncology

A 28-year-old man with Hereditary Multiple Exostoses (HME) reports a rapidly enlarging, painful mass on his posterior thigh. MRI reveals a sessile osteochondroma with a newly thickened cartilage cap measuring 3.5 cm. Which of the following histological features most strongly suggests malignant transformation to secondary chondrosarcoma?

. Presence of a thick fibrous perichondrium
. Increased cellularity with binucleated chondrocytes and myxoid changes
. Columnar organization of chondrocytes in the deep layer
. Endochondral ossification at the stalk base
. Uniform hyaline cartilage matrix

Correct Answer & Explanation

. Increased cellularity with binucleated chondrocytes and myxoid changes

Explanation

Secondary chondrosarcoma arising from an osteochondroma presents with a cartilage cap >2 cm in adults. Histologically, it is distinguished from benign cartilage by increased cellularity, pleomorphism, binucleation, and myxoid matrix changes.

Question 6704

Topic: 10. Pathology and Oncology

A 19-year-old male presents with a hard, painless mass on his proximal humerus. Radiographs are shown:

Imaging confirms a surface lesion causing saucerization of the underlying cortex with a sclerotic rim, but no medullary extension. Biopsy shows mature hyaline cartilage without atypia. What is the most likely diagnosis?

. Parosteal osteosarcoma
. Periosteal osteosarcoma
. Periosteal chondroma
. Chondromyxoid fibroma
. Juxtacortical chondrosarcoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondroma typically presents in young adults as a benign cartilaginous surface lesion that erodes the underlying cortex, creating a 'saucerized' defect bordered by sclerotic bone.

Question 6705

Topic: 10. Pathology and Oncology

A 65-year-old man sustains a pathologic fracture of the proximal humerus. Imaging shows a heavily calcified medullary lesion bordered by a highly aggressive, purely radiolucent area destroying the cortex. Histology reveals low-grade hyaline cartilage sharply juxtaposed next to a high-grade, non-cartilaginous spindle cell sarcoma. What is the diagnosis?

. Mesenchymal chondrosarcoma
. Clear cell chondrosarcoma
. Dedifferentiated chondrosarcoma
. Secondary chondrosarcoma
. Osteosarcoma with chondroblastic features

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a classic 'biphasic' histologic pattern where a low-grade cartilaginous tumor abruptly transitions into a high-grade spindle cell sarcoma. This portends a very poor prognosis.

Question 6706

Topic: 10. Pathology and Oncology

A 24-year-old female presents with a destructive rib lesion. Biopsy reveals a highly cellular tumor composed of sheets of primitive, undifferentiated small round blue cells interspersed with distinct islands of well-differentiated, benign-appearing hyaline cartilage. What is the most likely diagnosis?

. Ewing sarcoma
. Chondroblastoma
. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Synovial sarcoma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Mesenchymal chondrosarcoma is a rare, aggressive tumor that often affects the jaws, ribs, and extraosseous tissues. Its hallmark is a biphasic histology consisting of small round blue cells and islands of mature hyaline cartilage.

Question 6707

Topic: 10. Pathology and Oncology

A 45-year-old male has deep thigh pain at night. Imaging shows a 6 cm cartilaginous lesion in the femoral diaphysis with focal endosteal scalloping involving 75% of the cortex. Core biopsy returns 'Atypical Cartilaginous Tumor / Grade 1 Chondrosarcoma'. What is the most appropriate joint-preserving surgical approach for this lesion?

. Extended intralesional curettage with high-speed burring and chemical adjuvant
. Primary radiation therapy followed by observation
. Marginal excision with a 1 mm soft tissue margin
. Amputation proximal to the lesion
. Neoadjuvant chemotherapy followed by standard curettage

Correct Answer & Explanation

. Extended intralesional curettage with high-speed burring and chemical adjuvant

Explanation

Recent guidelines support treating appendicular Atypical Cartilaginous Tumors (Grade 1 chondrosarcoma) with extended intralesional curettage, high-speed burring, and adjuvants (e.g., phenol, cryotherapy) to preserve function while maintaining low recurrence rates.

Question 6708

Topic: 10. Pathology and Oncology

A 12-year-old boy is diagnosed with Ewing sarcoma of the left ilium. During the initial staging workup, which of the following represents the single most significant prognostic factor for his overall survival?

. Tumor size greater than 8 cm
. Presence of a t(11;22) chromosomal translocation
. Pelvic location of the primary tumor
. Presence of distant metastasis at the time of diagnosis
. Elevated serum alkaline phosphatase

Correct Answer & Explanation

. Presence of distant metastasis at the time of diagnosis

Explanation

While pelvic location and large tumor volume are poor prognostic indicators, the presence of distant metastasis (primarily lung and bone marrow) at the time of diagnosis is the single most critical factor determining overall survival in Ewing sarcoma.

Question 6709

Topic: 10. Pathology and Oncology

A 70-year-old man presents with left thigh pain and a monoclonal gammopathy. The AP radiograph is shown. Which of the following is the most appropriate definitive orthopedic management to prevent a pathologic fracture in this patient?

. Wide resection and endoprosthetic reconstruction
. Prophylactic internal fixation with a locked intramedullary rod
. Open curettage and bone grafting
. Radiation therapy alone
. Dynamic hip screw fixation

Correct Answer & Explanation

. Prophylactic internal fixation with a locked intramedullary rod

Explanation

Correct Answer: BThe underlying diagnosis is multiple myeloma. Because the patient has a large lucent lesion in the peritrochanteric region of the left proximal femur, the risk of pathologic fracture is high. Consideration should be given to prophylactic internal fixation with a locked intramedullary rod. The lesion does not appear to be a sarcoma requiring wide resection and endoprosthetic reconstruction. Neither chemotherapy nor radiation therapy alone is likely to result in long-term stabilization of the proximal femur.

Question 6710

Topic: 10. Pathology and Oncology

A patient presents with back pain. An AP radiograph of the thoracolumbar spine is shown. The 'winking owl' sign observed is most characteristic of which of the following pathologic processes?

. Congenital absence of the pedicle
. Pyogenic spondylodiscitis
. Metastatic tumor involvement of the pedicle
. Inflammatory spondyloarthropathy
. Traumatic pedicle fracture

Correct Answer & Explanation

. Metastatic tumor involvement of the pedicle

Explanation

Correct Answer: CThe figure shows the missing pedicle or 'winking owl' sign that is characteristic of tumor involvement of the cortical bone of the pedicle. None of the other pathologic processes commonly gives this radiographic picture. Thinned, but not missing pedicles, have been described as a normal variant.

Question 6711

Topic: 10. Pathology and Oncology

A 14-year-old patient presents with anterior knee pain. Imaging and biopsy are performed. Histologic examination reveals sheets of small round blue cells. Which of the following genetic translocations is most consistently associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: BThe histology shows small round blue cells that are typical of Ewing's sarcoma. Ewing's sarcoma has been noted to have a consistent genetic translocation t(11;22). Although Ewing's sarcoma frequently occurs in the diaphysis, it can occur in the metaphysis.

Question 6712

Topic: 10. Pathology and Oncology

A 72-year-old woman presents with thigh pain after a fall. She has a history of increasing thigh pain prior to the fall. The radiograph shows a midstem periprosthetic fracture. What is the most likely underlying etiology contributing to this complication?

. Modulus mismatch
. Chronic infection
. Loosening of the prosthesis
. Osteolysis
. Metastatic tumor

Correct Answer & Explanation

. Loosening of the prosthesis

Explanation

Correct Answer: CThe patient has a midstem periprosthetic fracture, which commonly results in loosening of the prosthesis. Although the patient reported a fall, her history is also consistent with preexisting loosening of the prosthesis. Chronic infection has been shown in up to 16% of these fractures; however, the patient's work-up revealed no infection.

Question 6713

Topic: 10. Pathology and Oncology

A 16-year-old girl is evaluated for an asymptomatic proximal femur lesion discovered incidentally after a fall. Biopsy reveals spicules of woven bone without osteoblastic rimming in a bland fibrous background. Which of the following is the most appropriate management for this asymptomatic lesion?

. Wide resection and endoprosthetic reconstruction
. Curettage and bone grafting
. Prophylactic intramedullary nailing
. Observation
. Radiation therapy

Correct Answer & Explanation

. Observation

Explanation

Correct Answer: DThe histologic finding of spicules of woven bone without osteoblastic rimming in a bland fibrous background is diagnostic of fibrous dysplasia. Observation is indicated in the absence of symptoms, impending fracture, or deformity. Fibrous dysplasia most commonly occurs in the proximal femur.

Question 6714

Topic: 10. Pathology and Oncology

The provided radiograph demonstrates a 'winking owl' sign. This radiographic finding is most directly caused by tumor involvement and destruction of which of the following anatomical structures?

. Spinous process
. Transverse process
. Pars interarticularis
. Pedicle
. Vertebral body

Correct Answer & Explanation

. Vertebral body

Explanation

Correct Answer: DThe 'winking owl' sign is characteristic of tumor involvement of the cortical bone of the pedicle, leading to a missing pedicle on an AP radiograph. None of the other pathologic processes or anatomical structures commonly give this specific radiographic picture. Thinned, but not missing, pedicles have been described as a normal variant, but complete absence is highly suspicious for metastatic disease or tumor.

Question 6715

Topic: 10. Pathology and Oncology

A 14-year-old patient presents with anterior knee pain. Imaging and biopsy specimens are shown. Histology reveals small round blue cells. Which of the following genetic translocations is most characteristically associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: AThe imaging and histology (small round blue cells) are diagnostic of Ewing's sarcoma. Ewing's sarcoma is characteristically associated with the t(11;22) genetic translocation. Other translocations listed correspond to different sarcomas: t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 6716

Topic: 10. Pathology and Oncology

A 16-year-old girl is evaluated for an asymptomatic hip lesion discovered incidentally after a fall. Imaging and biopsy are provided. Which of the following histologic features is considered the hallmark of this condition?

. Small round blue cells with Homer-Wright rosettes
. Spicules of woven bone without osteoblastic rimming in a bland fibrous background
. Malignant spindle cells producing osteoid matrix
. Multinucleated giant cells in a background of mononuclear stromal cells
. Cartilage cap with underlying enchondral ossification

Correct Answer & Explanation

. Spicules of woven bone without osteoblastic rimming in a bland fibrous background

Explanation

Correct Answer: BThe imaging and histology are diagnostic of fibrous dysplasia. The classic histologic finding of fibrous dysplasia is spicules of woven bone (often described as 'Chinese characters') without osteoblastic rimming, set in a bland fibrous background. Observation is indicated in the absence of symptoms, impending fracture, or severe deformity.

Question 6717

Topic: 10. Pathology and Oncology

A 65-year-old man presents with insidious onset of back pain. An AP radiograph of the thoracolumbar spine is shown. The radiographic 'winking owl' sign observed is most characteristic of which of the following pathophysiologic processes?

. Congenital absence of the pedicle
. Pyogenic osteomyelitis
. Metastatic destruction of the cortical bone of the pedicle
. Tuberculous spondylitis
. Inflammatory spondyloarthropathy

Correct Answer & Explanation

. Metastatic destruction of the cortical bone of the pedicle

Explanation

Correct Answer: CThe 'winking owl' sign on an AP radiograph of the spine is caused by the absence or destruction of a pedicle. This is highly characteristic of tumor involvement (often metastatic) destroying the cortical bone of the pedicle. Infections and inflammatory processes typically involve the disc space and endplates rather than isolated pedicle destruction.

Question 6718

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with anterior knee pain. Imaging and biopsy are performed (Figures A and B). Histologic examination reveals sheets of small round blue cells. Which of the following genetic translocations is most consistently associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Correct Answer: AThe clinical, radiographic, and histologic findings (small round blue cells) are diagnostic of Ewing's sarcoma. Ewing's sarcoma is characterized by the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 6719

Topic: Bone Tumors

A 16-year-old girl undergoes radiographic evaluation after a minor fall, revealing an incidental proximal femoral lesion (Figure A). A biopsy is performed (Figure B). The histologic presence of spicules of woven bone without osteoblastic rimming in a bland fibrous stroma is pathognomonic for which of the following conditions?

. Osteosarcoma
. Osteoblastoma
. Fibrous dysplasia
. Nonossifying fibroma
. Unicameral bone cyst

Correct Answer & Explanation

. Fibrous dysplasia

Explanation

Correct Answer: CThe histologic description of 'Chinese character' spicules of woven bone lacking osteoblastic rimming, set within a bland fibrous background, is the classic hallmark of fibrous dysplasia. While the radiographic appearance can sometimes mimic other lesions, the histology is diagnostic. In asymptomatic patients without impending fracture, observation is appropriate.

Question 6720

Topic: 10. Pathology and Oncology
A 13-year-old girl presents with a firm, painful mass in her right shoulder. Radiographs and biopsy specimens are obtained. The histologic section demonstrates highly pleomorphic spindle cells directly producing an amorphous, eosinophilic extracellular matrix. This matrix is best identified as:
. Chondroid
. Osteoid
. Amyloid
. Myxoid
. Collagen type III

Correct Answer & Explanation

. Osteoid

Explanation

The diagnosis is osteosarcoma. The defining histologic feature of osteosarcoma is the direct production of osteoid (immature, unmineralized bone matrix) by malignant mesenchymal cells. The radiograph shows an aggressive, bone-forming lesion in the proximal humerus, typical of osteosarcoma in a pediatric patient.

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