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10. Pathology and Oncology MCQs

Practice Set 349 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 6961

Topic: 10. Pathology and Oncology

A biopsy of an eccentric, lytic metaphyseal lesion in a 25-year-old male shows a lobular architecture with stellate and spindle-shaped cells in a myxoid and chondroid background. Multinucleated giant cells are present at the lobular periphery. What is the diagnosis?

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

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

The histological hallmark of Chondromyxoid fibroma (CMF) is its lobular pattern of stellate/spindle cells in a myxochondroid background, with hypercellular fibrous septa containing osteoclast-like giant cells at the periphery of the lobules.

Question 6962

Topic: Bone Tumors

A 20-year-old male presents with chronic pain below the knee. A radiograph is obtained.

Which radiographic description best characterizes this lesion, consistent with Chondromyxoid fibroma?

. A centrally located epiphyseal lesion with stippled calcifications
. An eccentric, sharply circumscribed metaphyseal lucency with a sclerotic rim
. A permeative diaphyseal lesion with Codman's triangle
. An expansile diaphyseal lesion giving a ground-glass appearance
. A cortical lucency with a surrounding dense sclerotic nidus

Correct Answer & Explanation

. An eccentric, sharply circumscribed metaphyseal lucency with a sclerotic rim

Explanation

CMF typically presents as an eccentric, geographic, osteolytic lesion in the metaphysis with a well-defined, scalloped sclerotic margin. Intralesional calcification is rarely visible on plain radiographs.

Question 6963

Topic: 10. Pathology and Oncology

A 5-year-old child with Hunter syndrome (MPS II) is scheduled for elective bilateral hip osteotomies. Which of the following is the most critical perioperative consideration for the anesthesia team?

. Susceptibility to malignant hyperthermia
. Difficult airway management due to upper airway mucopolysaccharide deposition
. High risk of fatal intraoperative coagulopathy
. Severe post-operative hypercalcemia
. Myocardial ischemia due to early atherosclerosis

Correct Answer & Explanation

. Difficult airway management due to upper airway mucopolysaccharide deposition

Explanation

Patients with MPS (especially Hurler and Hunter syndromes) accumulate glycosaminoglycans in their upper airway tissues (macroglossia, stiff tissues) and have a short neck, making them extremely difficult to intubate and at high risk for perioperative airway loss.

Question 6964

Topic: 10. Pathology and Oncology

A 25-year-old female undergoes a biopsy for a painful, eccentric, osteolytic lesion in the proximal tibial metaphysis with a well-defined sclerotic margin.

Histological analysis shows stellate cells in a myxoid background with osteoclast-like giant cells at the periphery of lobules. What is the most common genetic alteration associated with this tumor?

. GNAS1 mutation
. EXT1/EXT2 mutation
. GRM1 gene rearrangement
. USP6 gene rearrangement
. H3F3A mutation

Correct Answer & Explanation

. GRM1 gene rearrangement

Explanation

The lesion is a Chondromyxoid Fibroma (CMF), which frequently involves a rearrangement of chromosome 6q25, leading to promoter swapping and upregulation of the GRM1 (glutamate receptor 1) gene. This mutation is found in up to 80% of CMF cases.

Question 6965

Topic: 10. Pathology and Oncology

A 28-year-old male is diagnosed with a chondromyxoid fibroma of the proximal tibia after an incisional biopsy. He is neurologically intact with a stable knee joint. Which of the following is the most appropriate definitive surgical management?

. Wide extra-articular en bloc resection
. Extended intralesional curettage with high-speed burring and bone grafting
. Radiofrequency ablation
. Intralesional steroid injection
. Amputation

Correct Answer & Explanation

. Extended intralesional curettage with high-speed burring and bone grafting

Explanation

Chondromyxoid fibroma is a benign but locally aggressive cartilaginous tumor. The standard of care to minimize recurrence while preserving joint function is extended intralesional curettage with the use of a high-speed burr, followed by bone grafting or cementation.

Question 6966

Topic: 10. Pathology and Oncology

A 50-year-old patient undergoes an MRI for a suspected Primary Bone Lymphoma of the humerus. Which of the following MRI characteristics is most typically associated with this malignancy?

. High T1 signal intensity due to intralesional fat
. Low to intermediate T1 signal with surrounding extensive soft tissue mass and minimal cortical disruption
. Fluid-fluid levels on T2-weighted imaging diagnostic of the primary tumor
. Target sign with a hyperintense center and a hypointense rim
. Drop-out signal on out-of-phase imaging indicating microscopic fat

Correct Answer & Explanation

. Low to intermediate T1 signal with surrounding extensive soft tissue mass and minimal cortical disruption

Explanation

Primary bone lymphoma classically demonstrates low to intermediate signal on T1-weighted imaging with an extensive marrow and soft tissue component. A hallmark feature is the relative preservation of the cortical bone despite the large size of the marrow and soft tissue masses.

Question 6967

Topic: 10. Pathology and Oncology

In Chondromyxoid Fibroma, approximately 20% of cases may be complicated by secondary changes that can obscure the primary diagnosis on small biopsy samples. What is this common secondary histological finding?

. Malignant transformation to chondrosarcoma
. Secondary aneurysmal bone cyst (ABC) formation
. Extensive reactive woven bone mimicking osteosarcoma
. Langerhans cell histiocytosis infiltration
. Amyloid deposition

Correct Answer & Explanation

. Secondary aneurysmal bone cyst (ABC) formation

Explanation

Secondary aneurysmal bone cyst (ABC) changes can occur in approximately 20% of Chondromyxoid Fibromas. This can lead to misdiagnosis if a limited biopsy only samples the cystic, blood-filled spaces of the ABC component.

Question 6968

Topic: 10. Pathology and Oncology

Primary bone lymphoma can easily be confused with chronic osteomyelitis clinically and radiographically. Which of the following histological stains is most helpful in highlighting the characteristic dense connective tissue framework surrounding the malignant cells in lymphoma?

. Periodic acid-Schiff (PAS)
. Congo Red
. Reticulin stain
. Toluidine blue
. Prussian blue

Correct Answer & Explanation

. Reticulin stain

Explanation

Reticulin staining in primary bone lymphoma characteristically demonstrates a dense, intertwining network of reticulin fibers surrounding individual lymphoma cells. PAS is positive in Ewing sarcoma, while Toluidine blue highlights mucin/cartilage.

Question 6969

Topic: 10. Pathology and Oncology

A 21-year-old male with an eccentric, sharply circumscribed, osteolytic lesion in the proximal tibia is diagnosed with Chondromyxoid Fibroma. Radiographically, what is the typical character of the periosteal reaction associated with this lesion?

. Codman triangle
. Onion-skinning
. Sunburst appearance
. Solid, thick periosteal buttress at the margin
. There is typically no aggressive periosteal reaction unless there is a fracture

Correct Answer & Explanation

. There is typically no aggressive periosteal reaction unless there is a fracture

Explanation

Chondromyxoid Fibroma is a benign lesion (Lodwick Type 1A or 1B) that typically causes geographic bone destruction with a sclerotic inner margin. It expands the cortex but typically lacks aggressive periosteal reactions (like onion-skinning or sunburst) unless complicated by a pathological fracture.

Question 6970

Topic: 10. Pathology and Oncology

A 25-year-old female undergoes a biopsy of an eccentric, lytic metaphyseal lesion in her proximal tibia. The pathologist diagnoses a Chondromyxoid Fibroma (CMF). Which of the following is the defining histological hallmark of this tumor?

. Sheets of uniform, small round blue cells with scant cytoplasm
. A biphasic lobular pattern with hypocellular myxoid centers and hypercellular peripheries
. A uniform proliferation of benign chondrocytes in lacunae without atypia
. Chicken-wire calcifications surrounding mononuclear cells and multinucleated giant cells
. Woven bone trabeculae surrounded by a dense fibroblastic stroma

Correct Answer & Explanation

. A biphasic lobular pattern with hypocellular myxoid centers and hypercellular peripheries

Explanation

CMF is characterized microscopically by a distinct lobular architecture featuring hypocellular, myxoid or chondroid centers and hypercellular peripheries containing spindle cells and osteoclast-like giant cells. This biphasic pattern is essential for diagnosis.

Question 6971

Topic: 10. Pathology and Oncology

A 30-year-old presents with chronic knee pain. Imaging reveals the following lesion.

Biopsy confirms a benign cartilaginous tumor. What is the most common anatomical site for this specific tumor type?

. Distal femur metaphysis
. Proximal tibia metaphysis
. Proximal humerus epiphysis
. Distal radius diaphysis
. Calcaneus

Correct Answer & Explanation

. Proximal tibia metaphysis

Explanation

Chondromyxoid fibroma (CMF) is a rare benign primary bone tumor. While it can occur in various bones, it has a strong predilection for the long bones of the lower extremity, specifically the proximal tibial metaphysis.

Question 6972

Topic: 10. Pathology and Oncology

When working up a 60-year-old patient with a newly diagnosed primary bone lymphoma of the humerus, which staging study is absolutely essential and distinguishes the workup of this disease from that of primary bone sarcomas (e.g., osteosarcoma)?

. CT angiography of the affected limb
. Technetium-99m bone scintigraphy
. Bone marrow aspiration and biopsy along with whole-body PET-CT
. MRI of the complete neuraxis
. Diagnostic thoracoscopy

Correct Answer & Explanation

. Bone marrow aspiration and biopsy along with whole-body PET-CT

Explanation

Primary bone lymphoma requires accurate hematologic staging to ensure there is no systemic involvement. A whole-body PET-CT and a unilateral or bilateral bone marrow aspirate/biopsy are standard to rule out widespread systemic lymphoma.

Question 6973

Topic: 10. Pathology and Oncology

A 28-year-old patient undergoes surgical treatment for a progressively painful, biopsy-proven chondromyxoid fibroma in the distal femur. What is the standard surgical management that offers the lowest recurrence rate while preserving the joint?

. Simple intralesional curettage
. Extended intralesional curettage with high-speed burring and use of local adjuvants
. Wide en bloc resection with endoprosthetic reconstruction
. Amputation proximal to the joint
. Percutaneous radiofrequency ablation

Correct Answer & Explanation

. Extended intralesional curettage with high-speed burring and use of local adjuvants

Explanation

Chondromyxoid fibromas are locally aggressive benign tumors (Campanacci stage 2 or 3). The standard of care is extended intralesional curettage using a high-speed burr, often followed by local adjuvants (phenol, cryotherapy) and bone grafting or cementing, which significantly reduces the recurrence rate compared to simple curettage.

Question 6974

Topic: 10. Pathology and Oncology

A 55-year-old male was successfully treated for primary bone lymphoma of the distal femur 8 years ago using R-CHOP chemotherapy and localized radiation therapy (45 Gy). He now presents with a new onset of severe knee pain at rest and an aggressive, destructive lytic lesion on radiographs. What is the most likely diagnosis?

. Recurrence of primary bone lymphoma
. Chronic radiation osteomyelitis
. Secondary radiation-induced sarcoma
. Avascular necrosis of the distal femur
. Metastatic prostate carcinoma

Correct Answer & Explanation

. Secondary radiation-induced sarcoma

Explanation

A new, aggressive, destructive bone lesion arising in the field of prior radiation (usually >5 years post-exposure) is highly suspicious for a radiation-induced secondary sarcoma, most commonly osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma.

Question 6975

Topic: 10. Pathology and Oncology

While Chondromyxoid Fibroma (CMF) and Chondroblastoma are both rare, benign cartilaginous bone tumors, they have distinct classic presentations. Which feature best differentiates CMF from chondroblastoma clinically and radiographically?

. CMF exclusively occurs in the spine, whereas chondroblastoma occurs in long bones.
. CMF typically presents in the diaphysis, whereas chondroblastoma is metaphyseal.
. CMF is classically located in the metaphysis, whereas chondroblastoma almost always involves the epiphysis or apophysis.
. CMF is highly sensitive to radiation therapy, whereas chondroblastoma requires amputation.
. CMF frequently undergoes spontaneous malignant transformation, whereas chondroblastoma does not.

Correct Answer & Explanation

. CMF is classically located in the metaphysis, whereas chondroblastoma almost always involves the epiphysis or apophysis.

Explanation

The location of the tumor is a key differentiating feature. Chondroblastoma characteristically arises in the epiphysis (or apophysis) of long bones, whereas Chondromyxoid Fibroma is classically found in the metaphysis.

Question 6976

Topic: 10. Pathology and Oncology

A 48-year-old patient presents with a destructive diaphyseal lesion.

A core needle biopsy is taken, but the initial histology shows significant 'crush artifact' among the small round blue cells. Which adjunctive test on the fresh tissue sample is most reliable to confirm a suspected diagnosis of Primary Bone Lymphoma?

. Electron microscopy to identify Birbeck granules
. Flow cytometry to detect clonal B-cell populations
. Bacterial and fungal tissue cultures
. Polymerase chain reaction for EWS-FLI1 fusion
. Karyotyping for t(X;18) translocation

Correct Answer & Explanation

. Flow cytometry to detect clonal B-cell populations

Explanation

Lymphoma cells are extremely fragile and prone to 'crush artifact' on standard needle biopsy, obscuring cellular architecture. Submitting fresh tissue in saline for flow cytometry is highly reliable for identifying the clonal B-cell or T-cell populations characteristic of lymphoma.

Question 6977

Topic: 10. Pathology and Oncology

A 45-year-old male presents with deep right thigh pain. Radiographs demonstrate a subtle permeative diaphyseal lesion with minimal cortical destruction. However, MRI reveals extensive marrow replacement and a large soft tissue mass. Biopsy confirms primary bone lymphoma (diffuse large B-cell). What is the most appropriate initial treatment for this patient?

. Wide surgical resection and endoprosthetic reconstruction
. Neoadjuvant chemotherapy followed by limb-salvage surgery
. Systemic chemoradiation therapy alone
. Intralesional curettage, adjuvant cryotherapy, and bone grafting
. Above-knee amputation

Correct Answer & Explanation

. Systemic chemoradiation therapy alone

Explanation

Primary bone lymphoma is highly sensitive to chemotherapy and radiation. Systemic chemoradiation (e.g., R-CHOP) is the standard of care, and surgical intervention is strictly reserved for impending or actual pathologic fractures.

Question 6978

Topic: 10. Pathology and Oncology

An 18-year-old female presents with chronic dull knee pain. Radiographs show an eccentric, radiolucent, sharply marginated metaphyseal lesion in the proximal tibia.

Which of the following best describes the classic histologic appearance of this tumor?

. Sheets of uniform, small round blue cells with scant cytoplasm
. Fibrous stroma arranged in a storiform pattern with giant cells
. Lobules of stellate cells in a myxoid background separated by cellular fibrous septa
. Malignant cartilage producing a myxoid matrix with frequent mitoses
. Hyaline cartilage cap overlying mature trabecular bone

Correct Answer & Explanation

. Lobules of stellate cells in a myxoid background separated by cellular fibrous septa

Explanation

Chondromyxoid fibroma (CMF) is characterized histologically by a distinct lobular architecture. It features lobules of myxoid and chondroid tissue containing stellate cells, which are separated by highly cellular fibrous septa with osteoclast-like giant cells.

Question 6979

Topic: 10. Pathology and Oncology

A 55-year-old female presents with a destructive osteolytic lesion in the proximal humerus associated with a soft tissue mass. Following a biopsy, she is diagnosed with primary bone lymphoma. Which of the following imaging features is considered highly characteristic of this malignancy?

. A narrow zone of transition with a well-defined sclerotic rim
. Fluid-fluid levels universally pathognomonic on T2-weighted MRI
. Extensive intramedullary marrow replacement that exceeds the apparent cortical destruction on plain radiographs
. A characteristic 'fallen leaf' sign inside a purely lytic cavity
. Extensive 'popcorn' calcifications within the soft tissue mass

Correct Answer & Explanation

. Extensive intramedullary marrow replacement that exceeds the apparent cortical destruction on plain radiographs

Explanation

A classic imaging hallmark of primary bone lymphoma is an MRI demonstrating extensive bone marrow infiltration that is disproportionately large compared to the minimal cortical destruction seen on plain radiographs.

Question 6980

Topic: Bone Tumors

When distinguishing a chondromyxoid fibroma (CMF) from a chondroblastoma based on clinical and histologic criteria, which of the following features is most indicative of CMF?

. Predilection for the epiphysis of long bones prior to physeal closure
. Presence of 'chicken-wire' calcifications surrounding mononuclear cells
. Eccentric metaphyseal location with distinct lobular architecture
. Production of extensive and mature true hyaline cartilage
. Frequent association with secondary aneurysmal bone cysts

Correct Answer & Explanation

. Eccentric metaphyseal location with distinct lobular architecture

Explanation

CMF typically presents as an eccentric metaphyseal lesion with lobular architecture consisting of myxoid and chondroid zones. Chondroblastomas are classically epiphyseal and feature 'chicken-wire' calcifications.

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