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10. Pathology and Oncology MCQs

Practice Set 158 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 3141

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with chronic, dull back pain that is not completely relieved by NSAIDs. Imaging reveals a 3 cm expansile, partially sclerotic lesion in the posterior elements of L3.

Based on the clinical and radiographic findings, which of the following is true regarding this pathology?

. It typically measures less than 1.5 cm in diameter
. Malignant transformation to osteosarcoma is highly common
. Pain is characteristically dramatically relieved by aspirin
. Histology will show loose fibrovascular tissue with irregular osteoid
. It exclusively affects the anterior vertebral body

Correct Answer & Explanation

. Histology will show loose fibrovascular tissue with irregular osteoid

Explanation

The clinical and radiographic presentation is classic for an osteoblastoma, which typically affects the posterior elements of the spine and is >2 cm. Unlike osteoid osteomas, the pain is less predictably relieved by NSAIDs, and histology shows loose fibrovascular connective tissue with irregular osteoid.

Question 3142

Topic: 10. Pathology and Oncology

A 17-year-old girl undergoes biopsy of a solitary bone lesion. The photomicrograph is shown below.

The presence of loose fibrovascular connective tissue intermixed with irregular osteoid and normal-appearing mitotic figures most strongly supports which diagnosis?

. Osteosarcoma
. Osteoblastoma
. Chondroblastoma
. Ewing Sarcoma
. Fibrous Dysplasia

Correct Answer & Explanation

. Osteoblastoma

Explanation

The histology describes osteoblastoma, characterized by interlacing trabeculae of osteoid in a loose, highly vascular fibrous stroma. While mitotic figures may be present, the lack of atypical mitoses and absence of permeative destruction helps differentiate it from osteosarcoma.

Question 3143

Topic: Bone Tumors

A 16-year-old male presents with a 6-month history of chronic, dull back pain that is not completely relieved by NSAIDs. Radiographs reveal an expansile, lytic lesion in the posterior elements of L3.

What is the most likely diagnosis?

. Aneurysmal Bone Cyst
. Osteoid Osteoma
. Osteosarcoma
. Osteoblastoma
. Ewing Sarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastomas frequently involve the posterior elements of the spine and are classically larger than 2 cm. Unlike osteoid osteomas, the pain is typically less responsive to NSAIDs and less likely to be strictly nocturnal.

Question 3144

Topic: 10. Pathology and Oncology

A biopsy is taken from a 3 cm expansile lesion in the posterior elements of the cervical spine. Histological analysis reveals loose fibrovascular connective tissue intermixed with irregular osteoid and plump osteoblasts.

Which of the following is a primary characteristic distinguishing this condition from osteoid osteoma?

. Presence of chondroid matrix
. Lesion size greater than 2 cm
. Malignant potential within 5 years
. Inability to produce woven bone
. Positive staining for S-100

Correct Answer & Explanation

. Lesion size greater than 2 cm

Explanation

Osteoblastoma and osteoid osteoma share identical histology, featuring irregular osteoid lined by plump osteoblasts in a vascular stroma. They are distinguished primarily by size (osteoblastoma > 2 cm) and clinical symptoms.

Question 3145

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful mass on his distal femur. Radiographs show a permeative, diaphyseal lesion with an 'onion-skin' periosteal reaction. Which chromosomal translocation is most classically associated with this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma typically presents as a permeative diaphyseal lesion with onion-skinning. It is strongly associated with the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein.

Question 3146

Topic: Bone Tumors

A 9-year-old boy sustains a minor fall and presents with arm pain. Radiographs reveal a centrally located, lytic metaphyseal lesion in the proximal humerus with a 'fallen leaf' sign. Aspiration yields clear, yellow fluid. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Unicameral bone cyst
. Non-ossifying fibroma
. Chondroblastoma
. Osteosarcoma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

Unicameral (simple) bone cysts are fluid-filled, centrally located metaphyseal lesions commonly found in the proximal humerus or femur. A 'fallen leaf' sign represents a fractured piece of cortex settling at the bottom of the cystic cavity.

Question 3147

Topic: 10. Pathology and Oncology

Which of the following clinical features most accurately differentiates an osteoblastoma from an osteoid osteoma?

. Osteoblastomas are typically asymptomatic and discovered incidentally.
. Osteoblastomas commonly exhibit progressive, dull pain not dramatically relieved by salicylates.
. Osteoid osteomas have a high rate of malignant transformation.
. Osteoid osteomas present exclusively in the posterior elements of the spine.
. Osteoblastomas typically measure less than 1.5 cm in diameter.

Correct Answer & Explanation

. Osteoblastomas commonly exhibit progressive, dull pain not dramatically relieved by salicylates.

Explanation

Unlike osteoid osteomas, osteoblastomas produce dull, aching pain that is less strictly nocturnal and less predictably relieved by NSAIDs. Osteoblastomas are also defined by a size greater than 2 cm.

Question 3148

Topic: 10. Pathology and Oncology

A 14-year-old male presents with knee pain. Radiographs show a well-circumscribed, eccentrically placed, lytic lesion in the distal femoral epiphysis with a thin sclerotic rim. Histological examination shows mononuclear cells and areas of 'chicken-wire' calcification. What is the diagnosis?

. Giant cell tumor
. Osteochondroma
. Chondroblastoma
. Clear cell chondrosarcoma
. Enchondroma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare benign cartilage tumor that characteristically arises in the epiphysis of long bones in skeletally immature patients. 'Chicken-wire' calcification is the pathognomonic histologic feature.

Question 3149

Topic: 10. Pathology and Oncology

A 15-year-old girl presents with a rapidly growing mass on her distal femur. Biopsy reveals malignant spindle cells producing delicate, lace-like osteoid matrix. What is the most common subtype of this tumor?

. Conventional intramedullary osteosarcoma
. Parosteal osteosarcoma
. Periosteal osteosarcoma
. Telangiectatic osteosarcoma
. Secondary osteosarcoma

Correct Answer & Explanation

. Conventional intramedullary osteosarcoma

Explanation

Osteosarcoma is characterized by malignant cells producing an osteoid matrix. The conventional intramedullary subtype is the most common form, typically arising in the metaphyses of long bones in adolescents.

Question 3150

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with a solitary, 'punched-out' lytic skull lesion. Biopsy reveals cells with grooved nuclei (coffee-bean appearance) and eosinophils. Immunohistochemistry will likely be positive for which of the following markers?

. Cytokeratin and EMA
. CD1a and S-100
. CD99 and FLI-1
. Vimentin and SMA
. Desmin and Myogenin

Correct Answer & Explanation

. CD1a and S-100

Explanation

Langerhans Cell Histiocytosis (LCH), previously known as Eosinophilic Granuloma in its localized form, features Langerhans cells with coffee-bean nuclei and Birbeck granules on EM. They characteristically stain positive for CD1a and S-100.

Question 3151

Topic: 10. Pathology and Oncology

A 12-year-old boy with Multiple Hereditary Exostoses (MHE) is monitored for malignant transformation. Which anatomical location of an osteochondroma carries the highest risk of malignant transformation into a secondary chondrosarcoma?

. Distal femur
. Proximal tibia
. Distal radius
. Pelvis
. Phalanges

Correct Answer & Explanation

. Pelvis

Explanation

While osteochondromas are most common around the knee, lesions located in the pelvis, shoulder girdle, and proximal femur carry the highest risk for malignant transformation into secondary chondrosarcomas.

Question 3152

Topic: 10. Pathology and Oncology

An incidental finding on a knee radiograph of a 14-year-old male shows an eccentrically located, multilobulated lucent lesion with a sclerotic rim in the distal femoral metaphysis. Histology from a similar lesion typically shows spindle cells in a storiform pattern with foamy histiocytes. What is the most appropriate management?

. Observation
. Intralesional curettage and bone grafting
. Wide resection
. Radiofrequency ablation
. Neoadjuvant chemotherapy followed by excision

Correct Answer & Explanation

. Observation

Explanation

Non-ossifying fibromas (NOF) are common, benign, self-limiting lesions in children and adolescents. They are asymptomatic, discovered incidentally, and heal spontaneously by sclerosis, requiring only observation.

Question 3153

Topic: 10. Pathology and Oncology

An 11-year-old boy presents with fever, focal distal femur pain, and elevated inflammatory markers. Radiographs show a permeative diaphyseal lesion. Biopsy shows sheets of small round blue cells. Immunohistochemistry is strongly positive for CD99. Which of the following is the most important component of the initial treatment algorithm for this condition?

. Immediate wide surgical resection without biopsy
. Neoadjuvant multidrug chemotherapy
. Amputation
. Isolated radiation therapy
. Intralesional curettage and cementation

Correct Answer & Explanation

. Neoadjuvant multidrug chemotherapy

Explanation

The clinical presentation, small round blue cells, and CD99 positivity indicate Ewing sarcoma. The standard of care involves neoadjuvant systemic chemotherapy to address micrometastatic disease, followed by local control (surgery or radiation).

Question 3154

Topic: 10. Pathology and Oncology

A 19-year-old undergoes curettage of a 3.5 cm expansile lesion in the posterior elements of T12. Grossly, the tissue is a hemorrhagic, gritty, purplish-red friable mass.

What is the recommended standard surgical treatment for this benign but locally aggressive lesion?

. Observation
. Extended intralesional curettage and bone grafting
. Systemic chemotherapy
. Amputation
. External beam radiation alone

Correct Answer & Explanation

. Extended intralesional curettage and bone grafting

Explanation

Osteoblastomas are locally aggressive benign tumors. The standard treatment is extended intralesional curettage, high-speed burring of the cavity, and bone grafting, which provides a low recurrence rate.

Question 3155

Topic: 10. Pathology and Oncology

A 19-year-old female undergoes biopsy of an expansile lytic lesion in the posterior elements of L3.

The histology demonstrates irregular osteoid trabeculae in a vascular connective tissue stroma with prominent osteoblasts. What is the most likely diagnosis?

. Osteosarcoma
. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

The histology shows benign, irregular osteoid intermixed with loose fibrovascular connective tissue and prominent osteoblastic rimming, characteristic of osteoblastoma. It differs from osteosarcoma by lacking severe cytologic atypia and atypical mitoses.

Question 3156

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with right knee pain. Radiographs reveal a well-circumscribed, eccentrically located lytic lesion with a thin sclerotic rim within the proximal tibial epiphysis. Histology shows mononuclear cells with grooved nuclei and "chicken-wire" calcifications. Which immunohistochemical marker is characteristically positive in this tumor?

. CD99
. S-100
. MUC4
. Brachyury
. SOX9

Correct Answer & Explanation

. S-100

Explanation

Chondroblastomas are benign, epiphyseal cartilage-producing tumors that classically exhibit "chicken-wire" calcification and coffee-bean shaped nuclei. They are characteristically positive for S-100 and DOG1 on immunohistochemical staining.

Question 3157

Topic: 10. Pathology and Oncology

A 10-year-old girl presents with a permeative lytic lesion in the femoral diaphysis with an "onion-skin" periosteal reaction. A biopsy confirms Ewing sarcoma. Which of the following cytogenetic abnormalities is most commonly associated with this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation. This chromosomal abnormality fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, creating an oncogenic transcription factor.

Question 3158

Topic: 10. Pathology and Oncology

A 15-year-old boy has a biopsy-proven high-grade intramedullary osteosarcoma of the distal femur without distant metastasis. What is the standard treatment protocol for this patient?

. Primary amputation followed by radiation
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Wide surgical resection alone
. Radiation therapy followed by wide surgical resection
. Intralesional curettage with adjuvant chemotherapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

The standard of care for high-grade conventional osteosarcoma includes neoadjuvant chemotherapy, followed by wide surgical resection (favoring limb salvage if feasible), and concluding with adjuvant chemotherapy. This multidisciplinary approach maximizes long-term survival.

Question 3159

Topic: 10. Pathology and Oncology



A 16-year-old boy presents with a painful rigid scoliosis that is poorly relieved by NSAIDs. Radiographs and CT show a 3.5 cm expansile, radiolucent lesion in the posterior elements of L3. Histology reveals woven bone trabeculae rimmed by prominent osteoblasts without nuclear atypia. What is the most appropriate definitive management?

. Indefinite NSAID therapy
. Intralesional curettage and bone grafting
. Wide en bloc excision with negative margins
. Radiation therapy
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

Osteoblastoma is a benign bone-forming tumor characteristically larger than 2 cm, frequently presenting in the posterior elements of the spine. Unlike osteoid osteoma, it is less responsive to NSAIDs and is best managed with meticulous intralesional curettage and bone grafting.

Question 3160

Topic: 10. Pathology and Oncology



A biopsy from a symptomatic lytic bone lesion in the distal femur of a 14-year-old reveals the provided histology, showing loose fibrovascular connective tissue intermixed with irregular osteoid. Which of the following features most reliably differentiates this lesion clinically from an osteoid osteoma?

. Progressive, nocturnal pain relieved dramatically by salicylates
. Size greater than 2 centimeters in diameter
. Presence of malignant cartilage on histology
. Production of high levels of prostaglandin E2
. Predominant diaphyseal location in long bones

Correct Answer & Explanation

. Size greater than 2 centimeters in diameter

Explanation

Both osteoblastoma and osteoid osteoma share identical, benign histologic features of woven bone and vascular stroma. They are primarily distinguished by size, with osteoblastomas arbitrarily defined as being greater than 2 centimeters in diameter.

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