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10. Pathology and Oncology MCQs

Practice Set 191 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 3801

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with severe, deep bone pain in his leg. Imaging demonstrates a destructive diaphyseal lesion with a classic onion-skin periosteal reaction, as seen in

. A core biopsy reveals a proliferation of small blue round cells. Which of the following chromosomal translocations is most characteristic of this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical scenario and 'onion-skin' periosteal reaction describe Ewing sarcoma. This malignant bone tumor is characterized by the t(11;22)(q24;q12) translocation in approximately 85% of cases, resulting in the EWS-FLI1 fusion protein. t(9;22) is seen in extraskeletal myxoid chondrosarcoma and CML; t(2;13) in alveolar rhabdomyosarcoma; t(X;18) in synovial sarcoma; and t(12;16) in myxoid liposarcoma.

Question 3802

Topic: Bone Tumors

A 68-year-old female presents with severe back pain and generalized fatigue. Laboratory workup reveals hypercalcemia and a monoclonal spike on serum protein electrophoresis. Radiographs demonstrate multiple punched-out lytic lesions in her skull and vertebral bodies. Which of the following urinary findings is most characteristic of her underlying diagnosis?

. Elevated alkaline phosphatase
. Tartrate-resistant acid phosphatase (TRAP)
. Bence Jones proteins
. Homogentisic acid
. Hydroxyproline

Correct Answer & Explanation

. Bence Jones proteins

Explanation

The patient's presentation is classic for multiple myeloma, the most common primary malignancy of bone in adults. Bence Jones proteins (free light chains) are typically found in the urine of these patients.

Question 3803

Topic: 10. Pathology and Oncology

A 15-year-old female undergoes neoadjuvant chemotherapy followed by limb-salvage surgery for osteosarcoma of the distal femur. Pathological evaluation of the resected tumor is performed. Which of the following is the single most important prognostic factor for long-term survival in this patient?

. Initial tumor volume on MRI
. Specific histologic subtype (e.g., osteoblastic vs. chondroblastic)
. Percentage of tumor necrosis responding to neoadjuvant chemotherapy
. Age of the patient at the time of diagnosis
. Distance of the tumor from the joint line

Correct Answer & Explanation

. Percentage of tumor necrosis responding to neoadjuvant chemotherapy

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy (specifically >90% necrosis) is the single most important prognostic indicator for overall survival in patients with high-grade osteosarcoma.

Question 3804

Topic: Bone Tumors

A 15-year-old boy presents with severe right tibial pain that occurs predominantly at night and is dramatically relieved by NSAIDs. Imaging

reveals a cortical radiolucent nidus measuring 8 mm surrounded by dense reactive sclerosis. What is the most appropriate definitive minimally invasive treatment?

. Observation alone
. Radiofrequency ablation
. En bloc resection
. Core decompression
. Curettage and bone grafting

Correct Answer & Explanation

. Radiofrequency ablation

Explanation

The clinical presentation and imaging are classic for an osteoid osteoma (nidus <1.5 cm, nocturnal pain relieved by NSAIDs). Radiofrequency ablation (RFA) under CT guidance is the standard of care and the most appropriate minimally invasive definitive treatment, offering excellent success rates with minimal morbidity.

Question 3805

Topic: 10. Pathology and Oncology

A 30-year-old male presents with a slow-growing, painful soft tissue mass deep in his distal thigh near the knee joint. Histopathology reveals a biphasic pattern consisting of both spindle cells and epithelial cells. Molecular testing of the biopsy specimen demonstrates a t(X;18) chromosomal translocation. What is the most likely diagnosis?

. Ewing sarcoma
. Synovial sarcoma
. Osteosarcoma
. Chondrosarcoma
. Clear cell sarcoma

Correct Answer & Explanation

. Synovial sarcoma

Explanation

The presence of a biphasic histologic pattern (spindle and epithelial cells) and the characteristic t(X;18)(p11;q11) chromosomal translocation, which results in the SYT-SSX fusion gene, are pathognomonic for Synovial Sarcoma. Despite its name, synovial sarcoma rarely arises directly from joint synovium, often occurring in periarticular soft tissues of young adults.

Question 3806

Topic: 10. Pathology and Oncology
A 55-year-old woman presents with worsening thigh pain. Radiographs demonstrate a large, permeative lytic lesion in the proximal femur with intralesional 'popcorn' calcifications. An open biopsy confirms a high-grade (Grade III) conventional chondrosarcoma. What is the most appropriate definitive treatment?
. Neoadjuvant multidrug chemotherapy followed by wide surgical resection
. Wide surgical resection alone
. Intralesional curettage with adjuvant phenol and cementation
. Primary fractionated external beam radiation therapy
. Wide surgical resection followed by adjuvant radiation therapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcoma is notoriously resistant to both chemotherapy and radiation therapy. Therefore, the mainstay of treatment for high-grade (Grade II and III) lesions is wide surgical resection alone, typically with endoprosthetic reconstruction. Curettage is reserved only for low-grade (Grade I/atypical cartilaginous tumors) in specific anatomic locations.

Question 3807

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion exhibiting an 'onion-skin' periosteal reaction.

Biopsy confirms sheets of small, uniform, blue round cells with scant cytoplasm. Which of the following chromosomal translocations is most characteristic of this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical, radiographic, and histologic descriptions are classic for Ewing sarcoma. The most common chromosomal translocation associated with Ewing sarcoma is t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein. t(9;22) is seen in extraskeletal myxoid chondrosarcoma (and CML). t(2;13) is seen in alveolar rhabdomyosarcoma. t(X;18) is seen in synovial sarcoma. t(12;16) is seen in myxoid liposarcoma.

Question 3808

Topic: Bone Tumors

A 19-year-old male complains of severe, localized thigh pain that occurs primarily at night and is dramatically relieved by aspirin. Radiographs demonstrate an area of dense cortical sclerosis with a 6 mm radiolucent nidus. The intense pain associated with this lesion is mediated primarily by the local production of:

. Interleukin-1 (IL-1)
. Tumor necrosis factor-alpha (TNF-a)
. Prostaglandin E2 (PGE2)
. Substance P
. Histamine

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical presentation is classic for an osteoid osteoma. The nidus of an osteoid osteoma has a very high concentration of cyclooxygenase-2 (COX-2), which produces high levels of Prostaglandin E2 (PGE2). This massive localized PGE2 release is responsible for the intense pain, which explains why NSAIDs (which inhibit COX and thus PGE2 production) are highly effective in providing symptomatic relief.

Question 3809

Topic: Bone Tumors

A 15-year-old male presents with persistent knee pain. Radiographs reveal a metaphyseal lesion in the distal femur with a "sunburst" periosteal reaction.

Which of the following genetic syndromes is most strongly associated with this primary bone malignancy?

. Li-Fraumeni syndrome
. Neurofibromatosis type 1
. Marfan syndrome
. McCune-Albright syndrome
. Multiple hereditary exostoses

Correct Answer & Explanation

. Li-Fraumeni syndrome

Explanation

Osteosarcoma is the most common primary bone malignancy in children and is characterized by a "sunburst" periosteal reaction. It is strongly associated with Li-Fraumeni syndrome (p53 mutation) and hereditary retinoblastoma (Rb mutation).

Question 3810

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion with an "onion-skin" periosteal reaction. Biopsy confirms a small blue round cell tumor. Which of the following chromosomal translocations is most characteristic of this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. This is a highly characteristic diagnostic molecular marker.

Question 3811

Topic: 10. Pathology and Oncology

A 60-year-old woman with breast cancer presents with a lytic metastatic lesion in the peritrochanteric region of the proximal femur. It is moderately painful and involves 2/3 of the cortical diameter. What is her Mirels score and recommended management?

. 7, conservative management with radiation
. 8, prophylactic internal fixation
. 10, prophylactic internal fixation
. 11, prophylactic internal fixation
. 12, conservative management

Correct Answer & Explanation

. 10, prophylactic internal fixation

Explanation

The Mirels score components: Site (Lower limb = 2), Pain (Moderate = 2), Lesion nature (Lytic = 3), Size (2/3 of cortex = 3). Total = 10. A score of 9 or greater strongly warrants prophylactic internal fixation.

Question 3812

Topic: 10. Pathology and Oncology

A 35-year-old asymptomatic woman undergoes radiographs after a minor knee contusion. Imaging reveals a well-defined intramedullary lesion with "popcorn" calcifications in the distal femur.

What is the most appropriate next step in management?

. Open biopsy
. Core needle biopsy
. Reassurance and observation
. Intralesional curettage
. Wide surgical resection

Correct Answer & Explanation

. Reassurance and observation

Explanation

Asymptomatic enchondromas with classic radiographic features do not require biopsy or intervention. Observation with serial radiographs is appropriate management.

Question 3813

Topic: Bone Tumors

Which of the following MRI findings is most indicative of a low-grade chondrosarcoma rather than an enchondroma in a long bone?

. Lobular high T2 signal
. Endosteal scalloping involving >2/3 of the cortical thickness
. Presence of intralesional calcifications
. Small size (<3 cm)
. Absence of surrounding soft tissue edema

Correct Answer & Explanation

. Endosteal scalloping involving >2/3 of the cortical thickness

Explanation

Endosteal scalloping of more than two-thirds of the cortical thickness, cortical breakthrough, and a soft-tissue mass are strongly suggestive of chondrosarcoma. Enchondromas rarely cause deep endosteal scalloping in long bones.

Question 3814

Topic: Bone Tumors
A 20-year-old male presents with a painless mass over his proximal humerus. Imaging shows a surface lesion < 3 cm with a "saucerized" appearance of the underlying cortex and an intact sclerotic margin. What is the diagnosis?
. Periosteal osteosarcoma
. Osteochondroma
. Periosteal chondrosarcoma
. Periosteal chondroma
. Parosteal osteosarcoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas are benign surface lesions typically presenting with saucerization of the underlying cortex and sclerotic margins. They must be differentiated from periosteal chondrosarcomas, which are usually larger and lack the sclerotic rim.

Question 3815

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with multiple enchondromas and multiple dark blue, compressible soft tissue nodules on his extremities. He is at highest risk for developing which of the following?

. Thyroid carcinoma
. Chondrosarcoma
. Osteosarcoma
. Leukemia
. Pulmonary hamartoma

Correct Answer & Explanation

. Chondrosarcoma

Explanation

Maffucci syndrome involves multiple enchondromas and soft-tissue hemangiomas. These patients have a nearly 100% lifetime risk of malignant transformation, most commonly to chondrosarcoma, as well as visceral malignancies.

Question 3816

Topic: 10. Pathology and Oncology

A 45-year-old male with a known distal femur osteochondroma reports recent onset of pain and growth of the mass. An MRI is obtained. Which cartilage cap thickness is considered the threshold most concerning for malignant transformation in an adult?

. 2 mm
. 5 mm
. 10 mm
. 20 mm
. 50 mm

Correct Answer & Explanation

. 20 mm

Explanation

In adults, a cartilage cap thicker than 1.5 to 2.0 cm (15-20 mm) on MRI is highly suspicious for malignant transformation of an osteochondroma to a secondary chondrosarcoma. Growth or new pain in adulthood also warrants immediate investigation.

Question 3817

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with knee pain. Radiographs reveal a lucent lesion in the epiphysis of the proximal tibia with a thin sclerotic rim. Histology shows polygonal cells with grooved nuclei and "chicken-wire" calcifications. What is the diagnosis?

. Giant cell tumor
. Clear cell chondrosarcoma
. Chondromyxoid fibroma
. Chondroblastoma
. Enchondroma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare, benign epiphyseal tumor seen in skeletally immature patients. The classic histologic finding is "chicken-wire" pericellular calcification surrounding chondroblasts.

Question 3818

Topic: 10. Pathology and Oncology

A 40-year-old man presents with chronic hip pain. Imaging demonstrates a lytic lesion in the femoral head epiphysis. Biopsy reveals malignant chondrocytes with abundant clear cytoplasm. This lesion is frequently misdiagnosed clinically and radiographically as which of the following?

. Chondroblastoma
. Enchondroma
. Osteoid osteoma
. Ewing sarcoma
. Osteosarcoma

Correct Answer & Explanation

. Enchondroma

Explanation

Clear cell chondrosarcoma typically arises in the epiphysis of long bones in adults (30-50 years). Because of its epiphyseal location, it is most often radiographically misdiagnosed as a chondroblastoma, which typically occurs in younger patients.

Question 3819

Topic: 10. Pathology and Oncology

A 65-year-old woman with a known low-grade chondrosarcoma presents with sudden, rapid enlargement of the lesion. Biopsy reveals a bimorphic pattern: a low-grade cartilage tumor adjacent to a high-grade non-cartilaginous sarcoma. What is the expected prognosis?

. Excellent with wide excision alone
. Excellent with chemotherapy
. Poor with 5-year survival < 20%
. Moderate with targeted IDH1 inhibitors
. Spontaneous regression is likely

Correct Answer & Explanation

. Poor with 5-year survival < 20%

Explanation

Dedifferentiated chondrosarcoma presents with a classic bimorphic histological appearance. It is highly aggressive and carries a very poor prognosis, with a 5-year survival rate of 10-20%.

Question 3820

Topic: 10. Pathology and Oncology

A biopsy of a bone tumor reveals a biphasic pattern consisting of islands of well-differentiated hyaline cartilage interspersed with highly cellular areas of small, round blue cells in a hemangiopericytoma-like vascular pattern. What is the diagnosis?

. Dedifferentiated chondrosarcoma
. Clear cell chondrosarcoma
. Conventional chondrosarcoma
. Mesenchymal chondrosarcoma
. Ewing sarcoma

Correct Answer & Explanation

. Mesenchymal chondrosarcoma

Explanation

Mesenchymal chondrosarcoma is uniquely characterized by its biphasic histology: islands of benign-appearing cartilage mixed with primitive small round blue cells and a hemangiopericytomatous vascular pattern. It often occurs in the jaw or spine.

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