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10. Pathology and Oncology MCQs

Practice Set 241 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 4801

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with an enlarging, painful mass in the diaphysis of his left femur. Biopsy reveals sheets of small round blue cells. Cytogenetic analysis is ordered to confirm the diagnosis. Which chromosomal translocation is the diagnostic hallmark of this bone tumor?

. t(11;22)(q24;q12)
. t(9;22)(q34;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(X;18)(p11;q11)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The clinical scenario describes Ewing sarcoma. The diagnostic hallmark is the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion gene, present in over 85% of cases. t(9;22) is found in extraskeletal myxoid chondrosarcoma (and CML). t(12;16) is seen in myxoid liposarcoma. t(2;13) is characteristic of alveolar rhabdomyosarcoma. t(X;18) is pathognomonic for synovial sarcoma.

Question 4802

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. Biopsy reveals sheets of small round blue cells. Which of the following is the most common chromosomal translocation associated with this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22) translocation in over 90% of cases, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, t(2;13) in alveolar rhabdomyosarcoma, and t(12;16) in myxoid liposarcoma.

Question 4803

Topic: Bone Tumors

Which of the following histologic variants of osteosarcoma typically carries the most favorable prognosis following wide surgical resection without neoadjuvant chemotherapy?

. Telangiectatic osteosarcoma
. Parosteal osteosarcoma
. Periosteal osteosarcoma
. High-grade surface osteosarcoma
. Conventional osteosarcoma

Correct Answer & Explanation

. Parosteal osteosarcoma

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma that carries an excellent prognosis with wide surgical resection alone. Telangiectatic, high-grade surface, and conventional osteosarcomas are high-grade lesions that require systemic neoadjuvant and adjuvant chemotherapy.

Question 4804

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive diaphyseal lesion in his femur with an associated soft tissue mass. Biopsy reveals small round blue cells. The most likely cytogenetic abnormality driving this pathology is:

. t(9;22) resulting in BCR-ABL
. t(11;22)(q24;q12) resulting in EWS-FLI1
. t(X;18)(p11;q11) resulting in SYT-SSX
. t(12;16)(q13;p11) resulting in FUS-CHOP
. Mutations in the EXT1 or EXT2 genes

Correct Answer & Explanation

. t(11;22)(q24;q12) resulting in EWS-FLI1

Explanation

The patient has Ewing Sarcoma, characterized by small round blue cells. The classic genetic translocation is t(11;22)(q24;q12), which produces the EWS-FLI1 fusion protein.

Question 4805

Topic: 10. Pathology and Oncology

During a routine fracture fixation under general anesthesia, a patient develops generalized muscle rigidity, tachycardia, and rapidly rising core temperature. The definitive pharmacological treatment for this life-threatening condition acts by:

. Inhibiting acetylcholinesterase in the synaptic cleft
. Antagonizing non-depolarizing neuromuscular blockers
. Inhibiting calcium ion release from the sarcoplasmic reticulum via the ryanodine receptor
. Stimulating beta-2 adrenergic receptors in skeletal muscle
. Blocking voltage-gated sodium channels in the motor end plate

Correct Answer & Explanation

. Inhibiting calcium ion release from the sarcoplasmic reticulum via the ryanodine receptor

Explanation

The patient is experiencing Malignant Hyperthermia, caused by a mutation in the RYR1 gene. Dantrolene is the antidote, acting directly on the ryanodine receptor to inhibit massive calcium release from the sarcoplasmic reticulum.

Question 4806

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a pathological fracture of the proximal femur. Biopsy reveals a primary malignant bone tumor with a 'honeycomb' or 'bubbly' appearance on histology, characterized by cells containing abundant clear cytoplasm. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Clear cell chondrosarcoma
. Multiple myeloma

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade malignant bone tumor that commonly targets the epiphyses of long bones, particularly the proximal femur. Histologically, it is defined by a lobular architecture with cells demonstrating abundant clear cytoplasm and distinct cell membranes.

Question 4807

Topic: 10. Pathology and Oncology
A 70-year-old male with metastatic prostate cancer presents with progressive back pain and difficulty walking. MRI reveals an epidural tumor at T8 causing high-grade spinal cord compression. His Spinal Instability Neoplastic Score (SINS) is 10. He has good overall performance status and an estimated survival of > 1 year. Which of the following is the most appropriate next step in management?
. Conventional external beam radiation therapy (cEBRT) alone
. High-dose glucocorticoids and close observation
. Surgical decompression and stabilization followed by radiation
. Stereotactic radiosurgery alone
. Initiation of intravenous bisphosphonates alone

Correct Answer & Explanation

. Surgical decompression and stabilization followed by radiation

Explanation

According to the Neurologic, Oncologic, Mechanical, and Systemic (NOMS) framework, a SINS score of >= 7 indicates indeterminate or frank mechanical instability. Mechanical instability is an absolute indication for surgical stabilization regardless of tumor histology or radiosensitivity. Because the patient has high-grade epidural cord compression, instability, and a good prognosis, surgical decompression and stabilization followed by radiotherapy is indicated.

Question 4808

Topic: 10. Pathology and Oncology

A 55-year-old male presents with deep, persistent sacral pain and mild bowel dysfunction. Imaging reveals a large, destructive midline sacral mass extending to the S2 level. Histopathology demonstrates lobules of large cells with prominent intracytoplasmic vacuoles. Which of the following is the most appropriate definitive management for this lesion?

. Neoadjuvant chemotherapy followed by intralesional curettage
. En bloc wide surgical resection
. Primary external beam radiation therapy
. Radiofrequency ablation
. Observation with serial MRI scans

Correct Answer & Explanation

. En bloc wide surgical resection

Explanation

The clinical presentation and histology (physaliferous cells with large intracytoplasmic vacuoles) are pathognomonic for chordoma. Chordomas are slow-growing but locally aggressive, malignant primary bone tumors derived from notochord remnants. They are notoriously radioresistant and chemoresistant. The mainstay of treatment for sacral chordomas is en bloc wide surgical resection with negative margins, as intralesional resection inevitably leads to high local recurrence rates.

Question 4809

Topic: 10. Pathology and Oncology

A 60-year-old male with metastatic renal cell carcinoma presents with acute T8 paraparesis. MRI shows a T8 metastatic lesion causing high-grade epidural spinal cord compression. Based on the Neurologic, Oncologic, Mechanical, and Systemic (NOMS) framework, what is the optimal treatment strategy?

. Conventional external beam radiation therapy alone
. Stereotactic radiosurgery (SRS) alone
. Surgical separation (decompression) followed by SRS
. En bloc spondylectomy with clear margins
. Intravenous bisphosphonates and bracing

Correct Answer & Explanation

. Surgical separation (decompression) followed by SRS

Explanation

Renal cell carcinoma is traditionally radioresistant. For radioresistant tumors causing high-grade cord compression, the NOMS framework recommends "separation surgery" to decompress the cord and create a safe margin, followed by high-dose Stereotactic Radiosurgery (SRS).

Question 4810

Topic: 10. Pathology and Oncology

A 50-year-old active intravenous drug user presents with progressive back pain, fever, and markedly elevated CRP and ESR. MRI reveals T1 hypointensity and T2 hyperintensity in the L3-L4 disc space with destruction of the adjacent vertebral endplates. The patient is neurologically intact and hemodynamically stable. What is the most appropriate immediate next step in management?

. Immediate empirical intravenous broad-spectrum antibiotics
. CT-guided needle biopsy of the affected disc space
. Urgent anterior debridement, strut grafting, and fusion
. Lumbar laminectomy with epidural washout
. Discharge on outpatient oral antibiotics and a rigid brace

Correct Answer & Explanation

. CT-guided needle biopsy of the affected disc space

Explanation

In a hemodynamically stable patient with pyogenic spondylodiscitis and no neurological deficits, it is critical to establish a microbiological diagnosis via image-guided biopsy before initiating antibiotic therapy. Empiric antibiotics should be withheld to avoid falsely negative cultures.

Question 4811

Topic: 10. Pathology and Oncology
A 16-year-old boy diagnosed with conventional high-grade osteosarcoma of the distal femur completes a standard regimen of neoadjuvant chemotherapy. He subsequently undergoes wide surgical resection. According to the Huvos grading system, which histological finding is the most significant predictor of long-term survival?
. A decrease in serum alkaline phosphatase to normal levels
. A reduction in the primary tumor volume by > 50%
. Tumor necrosis > 90% in the resected specimen
. The loss of p53 tumor suppressor gene expression
. The formation of an intact fibrous pseudocapsule

Correct Answer & Explanation

. Tumor necrosis > 90% in the resected specimen

Explanation

The histological response to neoadjuvant chemotherapy is the single most important prognostic factor for conventional osteosarcoma. The Huvos grading system categorizes this response based on the percentage of tumor necrosis. A 'good response' is defined as Grade III (90-99% necrosis) or Grade IV (100% necrosis), which correlates directly with significantly improved disease-free and overall survival rates.

Question 4812

Topic: 10. Pathology and Oncology

A 13-year-old boy presents with night pain and swelling over the mid-thigh. Radiographs show an aggressive, permeative, diaphyseal lytic lesion of the femur with a multilaminated 'onion-skin' periosteal reaction. A core needle biopsy demonstrates uniform, small round blue cells. Cytogenetic analysis of this tumor is most likely to identify which of the following characteristic chromosomal translocations?

. t(9;22)(q34;q11)
. t(X;18)(p11;q11)
. t(2;13)(q35;q14)
. t(12;16)(q13;p11)
. t(11;22)(q24;q12)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The clinical, radiographic, and histologic presentation strongly points to Ewing sarcoma. Approximately 85-90% of Ewing sarcomas are characterized by a t(11;22)(q24;q12) chromosomal translocation, which results in the fusion of the EWSR1 gene on chromosome 22 with the FLI1 gene on chromosome 11. t(X;18) is seen in synovial sarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma. t(12;16) is seen in myxoid liposarcoma.

Question 4813

Topic: 10. Pathology and Oncology

A 16-year-old male presents with knee pain and a palpable mass over the distal femur. Radiographs reveal a metaphyseal lesion with a 'sunburst' periosteal reaction and Codman's triangle. A core needle biopsy demonstrates anaplastic spindle cells producing fine, lace-like osteoid. Following staging workup showing no metastasis, what is the most appropriate management sequence?

. Primary amputation followed by radiation therapy
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Wide surgical resection followed by radiation therapy
. Definitive radiation therapy alone
. Intralesional curettage and bone grafting

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

The clinical, radiographic, and histologic presentation is classic for conventional high-grade osteosarcoma. The standard of care for non-metastatic extremity osteosarcoma is neoadjuvant (preoperative) chemotherapy, followed by wide surgical resection (limb-salvage or amputation), and subsequent adjuvant (postoperative) chemotherapy. Radiation is typically reserved for unresectable tumors, as osteosarcoma is relatively radioresistant.

Question 4814

Topic: 10. Pathology and Oncology
A 55-year-old male presents with deep thigh pain. Radiographs reveal a lytic lesion in the proximal femur with endosteal scalloping and 'ring and arc' calcifications. Biopsy confirms a Grade II chondrosarcoma. What is the most appropriate surgical management?
. Intralesional curettage and bone grafting
. Intralesional curettage, phenol adjuvant, and cementation
. Wide surgical resection
. Radiation therapy followed by wide resection
. Neoadjuvant chemotherapy followed by wide resection

Correct Answer & Explanation

. Wide surgical resection

Explanation

Chondrosarcoma is classically resistant to both chemotherapy and radiation. Grade II and III chondrosarcomas of the pelvis and long bones require wide surgical resection to minimize local recurrence and maximize survival. Intralesional curettage is generally reserved for benign enchondromas or carefully selected, non-aggressive Grade I lesions (atypical cartilaginous tumors) in the appendicular skeleton.

Question 4815

Topic: 10. Pathology and Oncology

A 60-year-old male with a history of prostate cancer presents with severe thigh pain. Radiographs reveal a lytic lesion in the proximal femur involving 50% of the cortex, with an associated pain score of 8/10. According to Mirels' criteria, what is the appropriate management?

. Observation with crutches
. Radiation therapy alone
. Bisphosphonate therapy alone
. Prophylactic internal fixation followed by radiation
. Core needle biopsy and observation

Correct Answer & Explanation

. Prophylactic internal fixation followed by radiation

Explanation

Mirels' criteria assess the risk of pathologic fracture based on site, pain, lesion nature, and size. A score of 9 or greater strongly indicates the need for prophylactic internal fixation to prevent catastrophic failure.

Question 4816

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with right thigh pain and a low-grade fever. Radiographs show a diaphyseal permeative lytic lesion with an "onion skin" periosteal reaction. A biopsy is performed. Which specific chromosomal translocation is diagnostic for this patient's most likely condition?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The t(11;22)(q24;q12) translocation is found in approximately 85% of Ewing sarcoma cases, producing the EWS-FLI1 fusion protein.

Question 4817

Topic: 10. Pathology and Oncology

A 60-year-old male with a history of renal cell carcinoma presents with acute-onset bilateral lower extremity weakness. MRI reveals a large metastatic lesion at T10 causing high-grade epidural spinal cord compression. The NOMS framework is utilized to guide treatment. Given that renal cell carcinoma is highly radioresistant, what is the most appropriate management?

. Posterior decompression alone via laminectomy
. Conventional external beam radiation therapy (cEBRT) immediately
. Separation surgery followed by stereotactic body radiation therapy (SBRT)
. En bloc spondylectomy
. Vertebroplasty with cement augmentation

Correct Answer & Explanation

. Separation surgery followed by stereotactic body radiation therapy (SBRT)

Explanation

The NOMS (Neurologic, Oncologic, Mechanical, Systemic) framework dictates that for radioresistant tumors (like renal cell carcinoma, melanoma, thyroid, and GI tumors) causing high-grade epidural spinal cord compression, standard cEBRT is ineffective. SBRT is effective against radioresistant tumors but requires a 'safe margin' of 2-3 mm from the spinal cord to prevent radiation myelitis. Therefore, 'separation surgery' (decompression to create a margin) followed by post-operative SBRT is the gold standard.

Question 4818

Topic: 10. Pathology and Oncology

A 55-year-old male intravenous drug user presents with 4 weeks of severe localized back pain and low-grade fevers. He is neurologically intact. MRI confirms discitis and osteomyelitis at L3-L4 without spinal cord compression. Two sets of blood cultures are drawn and are negative at 48 hours. What is the most appropriate next step in management?

. Initiate broad-spectrum empiric intravenous antibiotics immediately
. Perform urgent open posterior surgical debridement and fusion
. Obtain a CT-guided needle biopsy of the L3-L4 disc space
. Repeat blood cultures and wait 7 more days
. Obtain an FDG-PET scan to confirm active infection

Correct Answer & Explanation

. Obtain a CT-guided needle biopsy of the L3-L4 disc space

Explanation

In a hemodynamically stable, neurologically intact patient with suspected pyogenic vertebral osteomyelitis/discitis, it is crucial to obtain a microbiologic diagnosis before initiating antibiotics. If blood cultures are negative, the gold standard next step is a percutaneous image-guided (CT-guided) biopsy of the affected disc space/vertebra. Empiric antibiotics should be withheld (if clinically safe) to maximize the yield of the biopsy.

Question 4819

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a deep, enlarging soft tissue mass in the anterior thigh. An MRI suggests a soft tissue sarcoma. Which of the following is a critical oncologic principle when performing an open incisional biopsy of this mass?

. Transverse incision to follow Langer lines and minimize scarring.
. Meticulous hemostasis utilizing a tourniquet during and after the procedure.
. Placing the incision longitudinally and in line with the planned future resection tract.
. Extensive soft tissue dissection to expose the entire neurovascular bundle for protection.
. Routing the drain, if used, to exit through a separate distant skin site outside the resection field.

Correct Answer & Explanation

. Placing the incision longitudinally and in line with the planned future resection tract.

Explanation

Biopsy tracts for suspected sarcomas must be placed longitudinally and directly in line with the definitive surgical incision. This ensures the entire biopsy tract can be excised en bloc with the tumor during definitive wide resection. Transverse incisions contaminate wider margins. Drains must exit directly in line with the incision within the planned resection field. Tourniquets, if used, should be deflated prior to closure to ensure absolute hemostasis, preventing post-operative hematoma which can contaminate adjacent compartments.

Question 4820

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphysial tibial lesion characterized radiographically by a 'hair-on-end' periosteal reaction. Core biopsy reveals sheets of small round blue cells staining positive for CD99. Cytogenetic analysis is most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma classically presents in the diaphysis of long bones in children and young adults. It is associated with the t(11;22)(q24;q12) translocation in over 85% of cases, resulting in the EWS-FLI1 fusion protein. Synovial sarcoma is associated with t(X;18) (SYT-SSX). Myxoid liposarcoma has t(12;16) (FUS-DDIT3). Alveolar rhabdomyosarcoma has t(2;13) (PAX3-FOXO1a). Extraskeletal myxoid chondrosarcoma has t(9;22).

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