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10. Pathology and Oncology MCQs

Practice Set 250 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 4981

Topic: 10. Pathology and Oncology

What is the primary goal of neoadjuvant (pre-operative) chemotherapy in Ewing's Sarcoma?

. To avoid the need for surgery completely.
. To improve patient nutrition before surgery.
. To reduce tumor size, treat micrometastatic disease, and assess tumor response.
. To definitively cure the local tumor without any further treatment.
. To induce a pathological fracture for easier tumor removal.

Correct Answer & Explanation

. To reduce tumor size, treat micrometastatic disease, and assess tumor response.

Explanation

The primary goals of neoadjuvant chemotherapy in Ewing's Sarcoma are to reduce the primary tumor size (making surgical resection easier and potentially limb-sparing), to eradicate micrometastatic disease (which is often present at diagnosis even if not detectable), and to assess the tumor's chemosensitivity, which has prognostic implications. It is rarely intended to completely avoid surgery or achieve definitive local cure alone.

Question 4982

Topic: 10. Pathology and Oncology

In the context of Ewing's Sarcoma, what does 'PNET' refer to?

. Primary Neural Exudative Tumor
. Peripheral Neuroectodermal Tissue
. Primitive Neuroectodermal Tumor
. Post-Neoplastic Endothelial Thrombosis
. Pulmonary Nodule Etiology Testing

Correct Answer & Explanation

. Primitive Neuroectodermal Tumor

Explanation

PNET stands for Primitive Neuroectodermal Tumor. Historically, PNETs were considered a separate but related entity to Ewing's Sarcoma, often exhibiting more neuroectodermal differentiation. However, with advances in molecular diagnostics, both Ewing's Sarcoma and PNET are now recognized as part of the 'Ewing Sarcoma Family of Tumors' (ESFT) due to sharing the same characteristic EWSR1 gene translocations and biological properties. The term 'Ewing's Sarcoma' is now often used inclusively for all tumors in this family.

Question 4983

Topic: 10. Pathology and Oncology

A 13-year-old with Ewing's Sarcoma of the humerus is completing chemotherapy. An MRI shows residual tumor within the bone. What is the most appropriate next step for local control?

. Continue chemotherapy indefinitely until complete resolution.
. Perform surgical resection of the residual tumor, possibly with adjuvant radiation.
. Treat with high-dose steroids to shrink the residual tumor.
. Monitor with serial MRIs every month without intervention.
. Perform a repeat biopsy and restart a different chemotherapy regimen.

Correct Answer & Explanation

. Perform surgical resection of the residual tumor, possibly with adjuvant radiation.

Explanation

After neoadjuvant chemotherapy, residual tumor requires definitive local treatment. For a resectable lesion like in the humerus, surgical resection with negative margins is the preferred option. Depending on the achieved margins and tumor response, adjuvant radiation therapy may also be indicated. Continuing chemotherapy indefinitely is not standard, steroids are not definitive treatment, observation is inappropriate for residual disease, and a repeat biopsy and new chemotherapy are typically for progression or relapse, not for residual tumor after planned neoadjuvant therapy.

Question 4984

Topic: 10. Pathology and Oncology

Which of the following describes the typical histological appearance of Ewing's Sarcoma?

. Abundant osteoid production with spindle cells
. Large pleomorphic cells with prominent nucleoli arranged in a herringbone pattern
. Sheets of small, round, uniform cells with scant cytoplasm, often glycogen-rich
. Chondroid matrix with entrapped lacunae
. Multinucleated giant cells and mononuclear stromal cells

Correct Answer & Explanation

. Sheets of small, round, uniform cells with scant cytoplasm, often glycogen-rich

Explanation

Ewing's Sarcoma is a 'small round blue cell tumor.' Histologically, it consists of sheets of relatively uniform, small, round cells with scant, clear cytoplasm (due to high glycogen content, which can be demonstrated by PAS staining) and ill-defined cell borders. Nuclei are often round to oval with fine chromatin and inconspicuous nucleoli. Abundant osteoid is seen in osteosarcoma, pleomorphic cells in undifferentiated pleomorphic sarcoma, chondroid matrix in chondrosarcoma, and giant cells in giant cell tumor.

Question 4985

Topic: 10. Pathology and Oncology

Which skeletal location for Ewing's Sarcoma is generally associated with a poorer prognosis due to challenges in achieving adequate surgical margins and higher rates of recurrence?

. Distal femur
. Proximal tibia
. Ribs
. Phalanges of the hand
. Pelvis

Correct Answer & Explanation

. Pelvis

Explanation

Pelvic Ewing's Sarcomas are notoriously challenging due to the complex anatomy, proximity to vital structures (sacral nerves, bladder, rectum), and the difficulty in obtaining wide, tumor-free surgical margins. This often results in higher rates of local recurrence and generally a poorer prognosis compared to extremity tumors, even with multimodal treatment. Distal femur, proximal tibia, ribs, and phalanges, while serious, often allow for more straightforward surgical resections with clearer margins.

Question 4986

Topic: 10. Pathology and Oncology

Which investigation is crucial for detecting skip lesions and assessing the full intraosseous extent of Ewing's Sarcoma in a long bone?

. Plain X-ray
. CT scan of the primary site
. Bone scintigraphy (bone scan)
. MRI of the entire involved bone and adjacent joint
. Ultrasound

Correct Answer & Explanation

. MRI of the entire involved bone and adjacent joint

Explanation

MRI of the entire involved bone, extending from joint to joint and including the adjacent joints, is essential for accurately assessing the intramedullary extent of the tumor, its relationship to growth plates, neurovascular structures, and for detecting 'skip lesions' (discontinuous tumor foci within the same bone). Plain X-rays and CT scans provide less detailed information about marrow involvement and soft tissue extension. Bone scans detect metabolic activity but lack anatomical detail for precise local staging. Ultrasound is primarily for soft tissue masses.

Question 4987

Topic: 10. Pathology and Oncology

A 10-year-old presents with a diaphyseal femur lesion, fever, and elevated ESR. What is the most important initial step in differentiating Ewing's Sarcoma from osteomyelitis?

. Start empiric antibiotics for suspected osteomyelitis.
. Perform an open biopsy immediately.
. Obtain an MRI of the affected limb and a core needle biopsy.
. Monitor symptoms and repeat X-rays in 4-6 weeks.
. Order a white blood cell count and C-reactive protein only.

Correct Answer & Explanation

. Obtain an MRI of the affected limb and a core needle biopsy.

Explanation

Ewing's Sarcoma can mimic osteomyelitis both clinically (pain, fever, elevated inflammatory markers) and radiographically. The most important initial step is to perform an MRI to better characterize the lesion and then a core needle biopsy to obtain tissue for definitive diagnosis (histology, immunohistochemistry, molecular genetics). Starting empiric antibiotics without a diagnosis risks delaying cancer treatment. Open biopsy is more invasive than core needle biopsy and typically not the first biopsy choice. Monitoring symptoms or just blood tests is insufficient given the potential for malignancy.

Question 4988

Topic: 10. Pathology and Oncology

Which of the following describes the most common type of translocation seen in Ewing's Sarcoma?

. Reciprocal translocation involving chromosomes 11 and 22
. Deletion of a segment on chromosome 13
. Duplication of the entire chromosome 8
. Inversion within chromosome 17
. Translocation between chromosomes 9 and 22 without EWSR1 involvement

Correct Answer & Explanation

. Reciprocal translocation involving chromosomes 11 and 22

Explanation

The most common translocation in Ewing's Sarcoma is the reciprocal translocation t(11;22)(q24;q12), which results in the fusion of the EWSR1 gene on chromosome 22 with the FLI1 gene on chromosome 11. Other translocations involve EWSR1 with different partners, but t(11;22) is the defining and most frequent event. The other options describe genetic anomalies not typical of Ewing's Sarcoma.

Question 4989

Topic: 10. Pathology and Oncology

Which factor generally correlates with a more favorable prognosis in patients with localized Ewing's Sarcoma?

. Tumor volume greater than 200 ml
. Primary tumor in the pelvis
. Poor histologic response (less than 90% necrosis) to neoadjuvant chemotherapy
. Complete surgical resection with wide, negative margins (R0)
. Elevated baseline C-reactive protein (CRP)

Correct Answer & Explanation

. Complete surgical resection with wide, negative margins (R0)

Explanation

Complete surgical resection with wide, negative margins (R0) is a crucial factor for achieving local control and is strongly associated with a more favorable prognosis in localized Ewing's Sarcoma. Conversely, large tumor volume, pelvic primary sites, and poor histologic response to chemotherapy (indicating chemoresistance) are all associated with a poorer prognosis. Elevated CRP, like LDH, is a non-specific inflammatory marker that can indicate more aggressive disease and is generally a poor prognostic sign.

Question 4990

Topic: 10. Pathology and Oncology

What is the primary concern when considering neoadjuvant chemotherapy for an extensive pelvic Ewing's Sarcoma in a 14-year-old patient?

. The chemotherapy will delay the definitive diagnosis.
. The risk of chemotherapy-induced hypertension.
. The potential for inadequate tumor response and subsequent surgical challenges.
. Chemotherapy may cause immediate pathological fracture.
. The impact on cosmetic appearance of the skin.

Correct Answer & Explanation

. The potential for inadequate tumor response and subsequent surgical challenges.

Explanation

For extensive pelvic Ewing's, neoadjuvant chemotherapy is crucial to reduce tumor burden and facilitate resection. The primary concern is the potential for inadequate tumor response, which would not only indicate a resistant tumor but also make subsequent surgical resection extremely difficult, potentially leading to positive margins, high morbidity, or even unresectability. Diagnosis is established via biopsy before starting chemotherapy. Hypertension is not a primary concern with standard regimens. While pathological fractures can occur, they are not aprimaryconcern of chemotherapy itself but rather tumor progression or bone weakening. Cosmetic appearance is a lesser concern.

Question 4991

Topic: 10. Pathology and Oncology

Which finding on gross pathological examination of a resected Ewing's Sarcoma specimen would indicate a good response to neoadjuvant chemotherapy?

. Extensive viable tumor at the surgical margins.
. Less than 10% tumor necrosis.
. Large areas of fibrosis and necrosis with minimal viable tumor.
. Presence of multiple skip lesions.
. Intact periosteal reaction with no change in tumor size.

Correct Answer & Explanation

. Large areas of fibrosis and necrosis with minimal viable tumor.

Explanation

A good response to neoadjuvant chemotherapy is histologically characterized by extensive tumor necrosis (typically >90% necrosis is considered a good response) and replacement of tumor by fibrosis, often with a significant reduction in viable tumor cells. Extensive viable tumor, less than 10% necrosis, or multiple skip lesions would indicate poor response or progression. An intact periosteal reaction with no change in tumor size would suggest lack of response.

Question 4992

Topic: 10. Pathology and Oncology

The diagnosis of Ewing's Sarcoma often requires a multidisciplinary team approach. Which specialist is primarily responsible for the definitive histological and molecular diagnosis?

. Orthopedic Surgeon
. Pediatric Oncologist
. Radiation Oncologist
. Pathologist
. Radiologist

Correct Answer & Explanation

. Pathologist

Explanation

The pathologist is the specialist primarily responsible for the definitive histological diagnosis of Ewing's Sarcoma, often utilizing immunohistochemistry and molecular genetic studies (e.g., FISH for EWSR1 translocations) on biopsy specimens to confirm the diagnosis and differentiate it from other small round blue cell tumors. While all other specialists are crucial in the management, the pathologist makes the tissue diagnosis.

Question 4993

Topic: 10. Pathology and Oncology

Regarding tumor vascularity in Ewing's Sarcoma, which statement is most accurate?

. Ewing's Sarcoma is typically avascular, making surgical resection straightforward.
. It is a highly vascular tumor, which can complicate surgical resection and embolization may be considered pre-operatively.
. Tumor vascularity is not a factor in treatment planning.
. It exhibits minimal vascularity, leading to good response to radiation therapy alone.
. Vascularity is only significant in extraskeletal variants.

Correct Answer & Explanation

. It is a highly vascular tumor, which can complicate surgical resection and embolization may be considered pre-operatively.

Explanation

Ewing's Sarcoma can be a highly vascular tumor, and this vascularity can lead to significant intraoperative bleeding, complicating surgical resection. Pre-operative angiography with embolization of feeding vessels is sometimes considered, particularly for large or difficult-to-access tumors (e.g., pelvic or sacral), to reduce intraoperative blood loss. Tumor vascularity is an important consideration in treatment planning. Avascularity is not typical, and high vascularity does not mean good response to radiation alone.

Question 4994

Topic: 10. Pathology and Oncology

Which benign condition can mimic the 'onion-skin' periosteal reaction seen in Ewing's Sarcoma on plain radiographs?

. Osteoid osteoma
. Fibrous dysplasia
. Chronic osteomyelitis
. Non-ossifying fibroma
. Enchondroma

Correct Answer & Explanation

. Chronic osteomyelitis

Explanation

Chronic osteomyelitis, particularly Brodie's abscess, can produce a lamellated or 'onion-skin' periosteal reaction due to repeated episodes of inflammation and new bone formation, making differentiation from Ewing's Sarcoma challenging. This is why a biopsy is critical when clinical and radiographic features overlap. Osteoid osteoma typically causes a central lucent nidus with dense surrounding sclerosis. Fibrous dysplasia causes a 'ground glass' matrix. Non-ossifying fibroma is a well-defined cortical lesion. Enchondroma is an intramedullary cartilaginous tumor.

Question 4995

Topic: 10. Pathology and Oncology

For a patient with Ewing's Sarcoma involving a vertebra, what is the primary indication for surgical decompression?

. Routine procedure for all spinal Ewing's Sarcomas.
. When there is neurological deficit due to spinal cord compression.
. To prevent systemic metastasis.
. To improve the cosmetic outcome of the spine.
. To obtain a definitive diagnosis without prior biopsy.

Correct Answer & Explanation

. When there is neurological deficit due to spinal cord compression.

Explanation

Surgical decompression for spinal Ewing's Sarcoma is indicated primarily when there is neurological compromise or imminent risk of spinal cord compression, causing deficits such as motor weakness, sensory loss, or bowel/bladder dysfunction. It is an emergent procedure aimed at preserving neurological function, often followed by radiation and chemotherapy. It's not routine for all spinal tumors, does not prevent systemic metastasis, and isn't for cosmetic improvement or initial diagnosis.

Question 4996

Topic: 10. Pathology and Oncology

Which of the following is an expected complication of Ifosfamide, a common chemotherapy agent used in Ewing's Sarcoma?

. Cardiotoxicity (dose-dependent)
. Peripheral neuropathy
. Hemorrhagic cystitis
. Ototoxicity
. Pulmonary fibrosis

Correct Answer & Explanation

. Hemorrhagic cystitis

Explanation

Ifosfamide is an alkylating agent often used in Ewing's Sarcoma. Its most characteristic and serious toxicity is hemorrhagic cystitis, caused by the metabolite acrolein. This is typically prevented by co-administering Mesna (2-mercaptoethane sulfonate sodium). Cardiotoxicity is associated with Doxorubicin. Peripheral neuropathy with Vincristine. Ototoxicity with Cisplatin. Pulmonary fibrosis with Bleomycin or Busulfan (less common in Ewing's regimens).

Question 4997

Topic: 10. Pathology and Oncology

The concept of 'chemoprimary' management is often applied to Ewing's Sarcoma. What does this refer to?

. Chemotherapy being the sole treatment modality for all stages of disease.
. Surgical resection being performed before any chemotherapy.
. Chemotherapy is initiated as the first therapeutic step, followed by local control and further chemotherapy.
. Only radiation therapy is used initially, with chemotherapy reserved for recurrence.
. Chemotherapy is administered only after metastasis has been confirmed.

Correct Answer & Explanation

. Chemotherapy is initiated as the first therapeutic step, followed by local control and further chemotherapy.

Explanation

'Chemoprimary' management signifies that systemic chemotherapy is the initial therapeutic intervention for Ewing's Sarcoma, even before local control (surgery or radiation). This approach aims to treat micrometastatic disease early and reduce the primary tumor burden. Local control (surgery/radiation) follows, and then further systemic chemotherapy is administered. It is not the sole treatment, nor is surgery performed first, and radiation is not typically first line alone.

Question 4998

Topic: 10. Pathology and Oncology

What is the typical dose range for radiation therapy (external beam) used in the local control of Ewing's Sarcoma?

. 5-10 Gy
. 20-30 Gy
. 45-60 Gy
. 70-80 Gy
. 100+ Gy

Correct Answer & Explanation

. 45-60 Gy

Explanation

The typical dose range for external beam radiation therapy in Ewing's Sarcoma is generally between 45-60 Gy (or higher for gross residual disease), delivered in daily fractions over several weeks. This dose is necessary to achieve local tumor control. Doses below 45 Gy are typically insufficient for definitive treatment, while doses above 60 Gy significantly increase the risk of severe long-term complications, particularly in children.

Question 4999

Topic: 10. Pathology and Oncology
Which tumor marker is sometimes elevated in Ewing's Sarcoma, particularly in patients with larger tumor burdens, and can be used for monitoring, though it is non-specific?
. Alpha-fetoprotein (AFP)
. Beta-human chorionic gonadotropin (β-hCG)
. Carcinoembryonic antigen (CEA)
. Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP)
. Prostate-specific antigen (PSA)

Correct Answer & Explanation

. Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP)

Explanation

Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP) are non-specific markers of inflammation that are frequently elevated in Ewing's Sarcoma patients, especially with larger, more aggressive tumors. They can be monitored to assess disease activity and response to treatment, though they are not specific diagnostic markers. AFP and β-hCG are markers for germ cell tumors, CEA for adenocarcinomas, and PSA for prostate cancer.

Question 5000

Topic: 10. Pathology and Oncology

What is the most common site for Ewing's Sarcoma to metastasize to at the time of initial diagnosis?

. Brain
. Liver
. Lungs
. Kidneys
. Regional lymph nodes

Correct Answer & Explanation

. Lungs

Explanation

At the time of diagnosis, the lungs are the most common site for distant metastases in Ewing's Sarcoma, observed in approximately 25-30% of patients. Bone and bone marrow are the next most common sites. Brain, liver, and kidneys are less frequent initial metastatic sites. Regional lymph node involvement is less common than in many other solid tumors.

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