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10. Pathology and Oncology MCQs

Practice Set 148 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 2941

Topic: 10. Pathology and Oncology

A 28-year-old woman presents with a slowly enlarging, painless mass on the posterior aspect of her distal femur. Radiographs demonstrate a heavily ossified, lobulated mass arising from the posterior cortex with a broad base and no medullary involvement. Histology reveals mature bone trabeculae in a bland fibrous stroma. Which of the following represents the most likely diagnosis and its characteristic molecular profile?

. Periosteal osteosarcoma; MDM2/CDK4 amplification
. Parosteal osteosarcoma; MDM2/CDK4 amplification
. Classic high-grade osteosarcoma; TP53 mutation
. Osteochondroma; EXT1 mutation
. Myositis ossificans; GNAS mutation

Correct Answer & Explanation

. Parosteal osteosarcoma; MDM2/CDK4 amplification

Explanation

The clinical and radiographic presentation is classic for a parosteal osteosarcoma, a low-grade surface osteosarcoma that typically presents as a densely ossified mass on the posterior aspect of the distal femur. Histologically, it shows bland spindle cells and woven or lamellar bone. Parosteal osteosarcoma is characterized molecularly by ring chromosomes containing amplified sequences of 12q13-15, which includes the MDM2 and CDK4 genes. Periosteal osteosarcoma is typically intermediate grade, more chondroblastic, and often arises on the anterior tibia.

Question 2942

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a painful mass in his proximal thigh. Imaging shows a lytic lesion with intralesional popcorn-like calcifications in the proximal femur, accompanied by cortical destruction. A core needle biopsy confirms a grade II chondrosarcoma. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection alone
. Radiation therapy alone
. Primary amputation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Chondrosarcomas are largely resistant to conventional chemotherapy and radiation therapy due to their poor vascularity and slow growth rate. Therefore, wide surgical resection is the standard of care for intermediate (grade II) to high-grade chondrosarcomas. Intralesional curettage is only appropriate for latent, benign cartilaginous lesions like enchondromas or selected grade I atypical cartilaginous tumors in the appendicular skeleton.

Question 2943

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive leg pain and swelling. Radiographs show a permeative diaphyseal lesion of the femur with an 'onion-skin' periosteal reaction. A core needle biopsy reveals sheets of small, round, blue cells. Which of the following cytogenetic abnormalities is most characteristic of this diagnosis?

. t(X;18)
. USP6 rearrangement
. MDM2 amplification
. t(11;22)
. GNAS mutation

Correct Answer & Explanation

. t(11;22)

Explanation

This patient has Ewing sarcoma, characterized clinically by its diaphyseal location, permeative appearance, and 'onion-skin' periosteal reaction. Histologically, it presents as a small round blue cell tumor. The classic genetic abnormality is the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma; MDM2 amplification in parosteal osteosarcoma/atypical lipomatous tumors; USP6 in aneurysmal bone cysts; and GNAS mutations in fibrous dysplasia.

Question 2944

Topic: Bone Tumors

A 19-year-old male presents with dull, aching thigh pain that worsens at night and is completely relieved by ibuprofen. Radiographs and a CT scan reveal a 1 cm radiolucent nidus surrounded by dense sclerotic bone in the femoral diaphysis. What is the primary underlying biochemical mechanism for the characteristic pain pattern associated with this lesion?

. Compression of adjacent peripheral nerves
. Localized production of inflammatory cytokines (TNF-alpha)
. Microfractures in the surrounding sclerotic bone
. High levels of prostaglandins within the nidus
. Rapid periosteal expansion

Correct Answer & Explanation

. High levels of prostaglandins within the nidus

Explanation

The clinical presentation is classic for an osteoid osteoma. The intense night pain, which is exquisitely sensitive to nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin, is caused by the production of high levels of prostaglandins (specifically PGE2) by the osteoblasts within the central nidus. This local prostaglandin storm causes vasodilation and nerve irritation.

Question 2945

Topic: 10. Pathology and Oncology

A 28-year-old man presents with a slow-growing, deep-seated soft tissue mass near the plantar aspect of his foot. MRI shows a heterogenous mass adjacent to the plantar fascia. Biopsy reveals a biphasic tumor with both epithelial (glandular) and spindle cell components. Which of the following gene fusions is diagnostic for this tumor?

. SYT-SSX1 or SYT-SSX2 fusion
. EWS-FLI1 fusion
. FUS-CHOP fusion
. COL1A1-PDGFB fusion
. PAX3-FOXO1 fusion

Correct Answer & Explanation

. SYT-SSX1 or SYT-SSX2 fusion

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which leads to the formation of the SYT-SSX fusion gene. It often presents in young adults as a slow-growing mass in the extremities, especially around the knee or foot/ankle. Despite its name, it rarely arises within the joint space. EWS-FLI1 is associated with Ewing sarcoma. FUS-CHOP is associated with myxoid liposarcoma. COL1A1-PDGFB is associated with dermatofibrosarcoma protuberans (DFSP). PAX3-FOXO1 is associated with alveolar rhabdomyosarcoma.

Question 2946

Topic: 10. Pathology and Oncology

A 25-year-old woman presents with a painless, hard mass behind her knee. Radiographs reveal a densely ossified mass arising from the posterior cortex of the distal femur, with a thin radiolucent cleft (the 'string sign') separating part of the tumor from the underlying bone cortex. Histology reveals well-differentiated bone trabeculae in a bland fibrous stroma. Which of the following is true regarding this condition?

. It typically arises within the medullary canal
. It has a higher propensity for early pulmonary metastasis compared to conventional osteosarcoma
. First-line treatment is neoadjuvant chemotherapy
. It is characterized by MDM2 and CDK4 gene amplification
. The tumor primarily affects patients in their first decade of life

Correct Answer & Explanation

. It is characterized by MDM2 and CDK4 gene amplification

Explanation

The clinical and radiographic presentation ('string sign', posterior distal femur) describes a parosteal osteosarcoma, a low-grade surface osteosarcoma. Molecularly, it is characterized by ring chromosomes containing amplifications of the MDM2 and CDK4 genes on chromosome 12q13-15. Because it is a low-grade lesion, it has a lower risk of metastasis than conventional intramedullary osteosarcoma. First-line treatment is wide surgical resection; chemotherapy is generally not required unless there is dedifferentiation.

Question 2947

Topic: Bone Tumors
A 10-year-old girl is evaluated for a leg deformity and a limp. Radiographs of the proximal femur show an expansile, medullary lesion with a 'ground-glass' appearance and a Shepherd's crook deformity. Physical examination reveals a large café-au-lait spot on her back with irregular 'Coast of Maine' borders. Which of the following gene mutations is the primary cause of her condition?
. NF1
. GNAS1
. EXT1
. FGFR3
. RUNX2

Correct Answer & Explanation

. GNAS1

Explanation

This patient has McCune-Albright syndrome, which consists of polyostotic fibrous dysplasia, café-au-lait spots with irregular borders, and endocrine hyperfunction (e.g., precocious puberty). The underlying cause is an activating post-zygotic somatic mutation in the GNAS1 gene, which encodes the alpha subunit of the Gs protein. This leads to constitutive activation of adenylate cyclase and increased intracellular cAMP, disrupting normal bone remodeling and melanocyte function.

Question 2948

Topic: 10. Pathology and Oncology

A 65-year-old man presents with severe, atraumatic mid-back pain. Plain radiographs of the lumbar spine show a densely sclerotic, ivory-like vertebral body at L3 without significant loss of height or collapse. Which of the following primary malignancies is the most likely cause of this specific radiographic appearance?

. Prostate carcinoma
. Renal cell carcinoma
. Thyroid carcinoma
. Multiple myeloma
. Melanoma

Correct Answer & Explanation

. Prostate carcinoma

Explanation

Metastatic prostate carcinoma is the most common cause of purely osteoblastic (sclerotic) bony metastases in adult males. The resulting dense, sclerotic vertebra is classic for an 'ivory vertebra'. In contrast, metastases from renal cell carcinoma, thyroid carcinoma, multiple myeloma, and melanoma are classically osteolytic (bone-destroying). Breast and lung carcinomas can produce mixed osteolytic and osteoblastic lesions.

Question 2949

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, enlarging mass in the diaphysis of his left femur. Radiographs reveal a permeative lytic lesion with an 'onion-skin' periosteal reaction. Biopsy demonstrates sheets of small round blue cells. Which of the following genetic translocations is most characteristic of this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical presentation and histopathology are classic for Ewing sarcoma. Ewing sarcoma is characterized by a t(11;22) chromosomal translocation in approximately 85-90% of cases, leading to the EWS-FLI1 fusion protein. t(X;18) is associated with synovial sarcoma; t(9;22) with extraskeletal myxoid chondrosarcoma; t(2;13) with alveolar rhabdomyosarcoma; and t(12;16) with myxoid liposarcoma.

Question 2950

Topic: 10. Pathology and Oncology
A 16-year-old girl is diagnosed with a high-grade intramedullary osteosarcoma of the distal femur. She completes a course of neoadjuvant chemotherapy prior to surgical resection. What is the most significant prognostic factor for her long-term survival?
. Histologic subtype of the tumor
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Initial size of the tumor
. Patient's age at diagnosis
. Magnitude of serum alkaline phosphatase elevation

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

In patients with localized high-grade osteosarcoma, the histologic response of the tumor to neoadjuvant chemotherapy is the single most important prognostic factor for long-term survival. A 'good response' is typically defined as 90% or greater tumor necrosis (Huvos grade III or IV) at the time of definitive surgical resection.

Question 2951

Topic: 10. Pathology and Oncology

A 65-year-old smoker presents with a pathologic fracture of the proximal humerus. Biopsy reveals an adenocarcinoma. Immunohistochemistry is expected to show positivity for which of the following markers if the primary tumor is pulmonary in origin?

. Cytokeratin 7 (CK7) and Thyroid Transcription Factor-1 (TTF-1)
. Cytokeratin 20 (CK20) and CDX2
. Prostate-Specific Antigen (PSA) and NKX3.1
. Cytokeratin 5/6 and p63
. Vimentin and CD99

Correct Answer & Explanation

. Cytokeratin 7 (CK7) and Thyroid Transcription Factor-1 (TTF-1)

Explanation

Metastatic adenocarcinoma of the lung typically stains positive for CK7 and TTF-1. CK20 and CDX2 are commonly positive in colorectal carcinomas. PSA and NKX3.1 are specific for prostate cancer. Squamous cell carcinoma of the lung is typically p63 and CK5/6 positive. Vimentin and CD99 are markers often utilized in the workup of mesenchymal tumors such as Ewing sarcoma.

Question 2952

Topic: 10. Pathology and Oncology
A 15-year-old boy undergoes neoadjuvant chemotherapy followed by wide resection for conventional high-grade osteosarcoma of the distal femur. Histological analysis of the resected specimen shows 95% tumor necrosis. What is the most significant prognostic factor associated with this patient's long-term survival?
. Tumor size at presentation
. Histological subtype of the osteosarcoma
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Intramedullary versus surface extension of the primary tumor
. Patient's age and gender

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the most reliable prognostic indicator for overall survival in high-grade osteosarcoma. Greater than 90% necrosis (Huvos Grade III or IV) represents a good response and is strongly correlated with improved long-term disease-free survival.

Question 2953

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a large, destructive, permeative lytic lesion in the diaphysis of the distal femur. Biopsy reveals uniform sheets of small round blue cells. Cytogenetic analysis demonstrates a t(11;22)(q24;q12) chromosomal translocation. Which of the following fusion genes is diagnostic for this condition?

. SYT-SSX
. EWS-FLI1
. TLS-CHOP
. COL1A1-PDGFB
. PAX3-FKHR

Correct Answer & Explanation

. EWS-FLI1

Explanation

The clinical and histological scenario describes Ewing sarcoma, characterized by small round blue cells and the classic t(11;22)(q24;q12) translocation. This specific translocation results in the EWS-FLI1 fusion gene. For comparison: SYT-SSX is seen in synovial sarcoma t(X;18); TLS-CHOP is seen in myxoid liposarcoma t(12;16); COL1A1-PDGFB is associated with dermatofibrosarcoma protuberans; and PAX3-FKHR is seen in alveolar rhabdomyosarcoma t(2;13).

Question 2954

Topic: 10. Pathology and Oncology

Which of the following genetic abnormalities is most characteristic of a primary aneurysmal bone cyst (ABC)?

. t(11;22) involving EWSR1 and FLI1
. t(X;18) involving SYT and SSX
. Translocation t(16;17) involving the USP6 gene
. Amplification of MDM2 and CDK4
. Mutation in the GNAS1 gene

Correct Answer & Explanation

. Translocation t(16;17) involving the USP6 gene

Explanation

Primary aneurysmal bone cysts are now recognized as true neoplasms driven by rearrangement of the USP6 gene on chromosome 17p13, most commonly resulting from a t(16;17)(q22;p13) translocation. In contrast, t(11;22) is seen in Ewing sarcoma, t(X;18) is seen in synovial sarcoma, MDM2/CDK4 amplification is characteristic of atypical lipomatous tumors and parosteal osteosarcoma, and GNAS1 mutations are seen in fibrous dysplasia.

Question 2955

Topic: 10. Pathology and Oncology

A 60-year-old man presents with chronic, dull, aching thigh pain. Radiographs show a large, purely lytic lesion in the diaphysis of the femur with endosteal scalloping and no periosteal reaction. Laboratory tests reveal anemia, hypercalcemia, and elevated creatinine. Serum protein electrophoresis shows a monoclonal spike. Which of the following is true regarding the surgical management of a pending pathologic fracture in this patient?

. Prophylactic fixation is contraindicated until radiation therapy is completed
. Surgical stabilization should ideally be performed prior to radiation therapy
. The primary tumor must be excised with wide margins prior to fixation
. Preoperative embolization is required due to high tumor vascularity
. The lesion is highly chemoresistant, making wide excision the only viable option

Correct Answer & Explanation

. Surgical stabilization should ideally be performed prior to radiation therapy

Explanation

The patient's presentation is highly suggestive of multiple myeloma (lytic bone lesion, anemia, hypercalcemia, renal insufficiency, M-spike). For impending or actual pathologic fractures in multiple myeloma, surgical stabilization is typically performed first, followed by postoperative radiation therapy. Multiple myeloma is highly radiosensitive, but radiation prior to surgery can impair wound healing and bone consolidation. Preoperative embolization is typically reserved for highly vascular metastases like renal cell or thyroid carcinoma.

Question 2956

Topic: 10. Pathology and Oncology

A 35-year-old woman is evaluated for a slowly enlarging, painless mass on the posterior aspect of her distal thigh. Radiographs demonstrate a heavily ossified, lobulated mass attached to the posterior cortex of the distal femur with a broad base, but lacking involvement of the medullary canal. Molecular testing of the biopsy specimen is most likely to show which of the following abnormalities?

. Extrachromosomal ring chromosomes containing amplified MDM2 and CDK4
. A somatic mutation in the IDH1 or IDH2 gene
. Overexpression of the RUNX2 transcription factor
. t(2;13) chromosomal translocation
. t(9;22) BCR-ABL translocation

Correct Answer & Explanation

. Extrachromosomal ring chromosomes containing amplified MDM2 and CDK4

Explanation

The clinical and radiographic description is classic for parosteal osteosarcoma, a low-grade surface osteosarcoma that typically arises on the posterior aspect of the distal femur. Molecularly, parosteal osteosarcomas are characterized by supernumerary ring chromosomes leading to the amplification of the 12q13-15 region, which contains the MDM2 and CDK4 genes. IDH1/IDH2 mutations are common in enchondromas and chondrosarcomas.

Question 2957

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with progressive knee pain and a palpable mass in the distal femur. Radiographs reveal a metaphyseal ill-defined sclerotic lesion with aggressive periosteal reaction ('sunburst' pattern) and a Codman triangle. A biopsy confirms conventional high-grade intramedullary osteosarcoma. Which of the following statements regarding the expected treatment protocol is correct?

. Radiation therapy is the primary definitive treatment for local control
. Neoadjuvant chemotherapy is administered, followed by surgical resection and adjuvant chemotherapy
. Immediate amputation is required to prevent pulmonary metastasis
. Bisphosphonate therapy alone provides adequate local control
. Surgical resection with marginal margins followed by radiation therapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy is administered, followed by surgical resection and adjuvant chemotherapy

Explanation

The standard of care for conventional high-grade intramedullary osteosarcoma consists of neoadjuvant (preoperative) chemotherapy, followed by wide surgical resection (limb salvage or amputation depending on neurovascular involvement), and then adjuvant (postoperative) chemotherapy. The histologic response to neoadjuvant chemotherapy (percentage of tumor necrosis) is a critical prognostic factor. Osteosarcoma is highly radioresistant, so radiation therapy is typically not used for local control unless the tumor is unresectable.

Question 2958

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with severe thigh pain and a low-grade fever. Radiographs display a permeative lytic lesion in the diaphysis of the femur with a classic 'onion-skin' periosteal reaction. Histology reveals small, uniform, round blue cells. Which of the following chromosomal translocations is the pathognomonic hallmark of this disease?

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

Correct Answer & Explanation

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

Explanation

The clinical and histological presentation is highly characteristic of Ewing sarcoma. The t(11;22)(q24;q12) translocation, resulting in the EWSR1-FLI1 fusion gene, is present in about 85% of Ewing sarcoma cases. The t(X;18) translocation is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 2959

Topic: 10. Pathology and Oncology

In the multidisciplinary management of conventional high-grade osteosarcoma, which of the following factors is considered the most significant predictor of long-term patient survival?

. The anatomical location of the primary tumor
. The patient's age and gender at the time of presentation
. The specific histological subtype of the tumor
. The percentage of tumor necrosis following neoadjuvant chemotherapy
. Pre-treatment serum levels of alkaline phosphatase and LDH

Correct Answer & Explanation

. The percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the most reliable prognostic indicator for long-term survival in high-grade osteosarcoma. According to the Huvos grading system, a 'good response' is defined as greater than 90% tumor necrosis, which strongly correlates with a significantly better prognosis and lower risk of metastasis.

Question 2960

Topic: 10. Pathology and Oncology
A 58-year-old man presents with deep, progressive thigh pain. Radiographs reveal a heavily calcified medullary lesion in the proximal femur with endosteal scalloping involving 80% of the cortical thickness. Biopsy indicates atypical chondrocytes with binucleation and mucoid stroma. What is the most appropriate definitive management?
. Intralesional curettage, bone grafting, and prophylactic internal fixation
. Intralesional curettage with phenol or liquid nitrogen adjuvant, followed by cementation
. Wide surgical resection and endoprosthetic reconstruction
. Preoperative radiation therapy followed by marginal resection
. Neoadjuvant multi-agent chemotherapy followed by wide surgical resection

Correct Answer & Explanation

. Wide surgical resection and endoprosthetic reconstruction

Explanation

The clinical presentation, significant endosteal scalloping (greater than two-thirds of cortical thickness), and histological findings of binucleation and mucoid stroma indicate a high-grade (Grade II or III) conventional chondrosarcoma. Conventional chondrosarcomas are highly resistant to both chemotherapy and radiotherapy. The gold standard of care is wide surgical resection to achieve negative margins, followed by appropriate structural reconstruction.

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