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10. Pathology and Oncology MCQs

Practice Set 217 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 4321

Topic: 10. Pathology and Oncology

A 45-year-old female with a known history of polyostotic fibrous dysplasia presents with a progressively enlarging, painless mass in her quadriceps muscle. A core needle biopsy of the soft tissue mass reveals bland, stellate-to-spindle-shaped cells in an abundant hypovascular, mucopolysaccharide-rich myxoid stroma.

What is the most likely diagnosis for the soft tissue mass in the context of her underlying skeletal condition?

. Myxofibrosarcoma
. Intramuscular myxoma
. Plexiform neurofibroma
. Desmoid tumor
. Liposarcoma

Correct Answer & Explanation

. Intramuscular myxoma

Explanation

The patient has Mazabraud syndrome, which is characterized by the association of fibrous dysplasia (usually polyostotic) and one or more intramuscular myxomas. The histology describes a benign intramuscular myxoma, which classically presents as an avascular, hypocellular mass with abundant myxoid stroma. Both the fibrous dysplasia and the myxomas in this syndrome share a somatic activating mutation in the GNAS gene.

Question 4322

Topic: 10. Pathology and Oncology

A 58-year-old male presents with bowel and bladder dysfunction and sacral pain. Imaging reveals a large, destructive, midline mass in the sacrum. Biopsy demonstrates cords and lobules of large cells with abundant, vacuolated, bubbly cytoplasm set in a myxoid stroma.

Which of the following immunohistochemical markers is highly sensitive and specific for the diagnosis of this tumor?

. Cytokeratin
. Brachyury
. S100
. CD99
. SATB2

Correct Answer & Explanation

. Brachyury

Explanation

The vignette describes a Chordoma, a locally aggressive malignancy arising from remnants of the embryonic notochord. The cells with bubbly cytoplasm are 'physaliferous' cells. Brachyury, a transcription factor essential for notochordal development, is a highly sensitive and specific nuclear immunohistochemical marker for chordoma, reliably distinguishing it from chondrosarcoma. While chordomas also co-express cytokeratin and S100, these are not highly specific.

Question 4323

Topic: 10. Pathology and Oncology

A 14-year-old boy is diagnosed with Ewing Sarcoma of the ilium. Cytogenetics confirm a t(11;22) translocation resulting in the EWS-FLI1 fusion protein. At the time of diagnosis, which of the following represents the most significant adverse prognostic factor for overall survival?

. Age older than 10 years
. Pelvic location of the primary tumor
. Tumor size greater than 8 cm
. Presence of clinically detectable metastatic disease
. Elevated serum lactate dehydrogenase (LDH)

Correct Answer & Explanation

. Presence of clinically detectable metastatic disease

Explanation

While older age, large tumor size, elevated LDH, and pelvic location (axial skeleton) are all poor prognostic factors in Ewing Sarcoma, the presence of metastatic disease at the time of diagnosis is consistently the most powerful and significant adverse prognostic factor for overall survival. Patients with localized disease have a long-term survival rate of ~70-75%, whereas those with metastatic disease at presentation have a survival rate of <30%.

Question 4324

Topic: 10. Pathology and Oncology

A 62-year-old male with known metastatic clear cell renal cell carcinoma presents with progressive thigh pain and a substantial, lytic lesion in the proximal femur with an impending pathologic fracture.

Prophylactic stabilization with an intramedullary nail is planned. What is the most critical adjunctive procedure to perform 24-48 hours prior to surgical intervention?

. Postoperative radiation therapy simulation
. Administration of neoadjuvant systemic immunotherapy
. Preoperative selective arterial embolization of the lesion
. Intravenous bisphosphonate infusion to harden the cortex
. Prophylactic stabilization of the contralateral asymptomatic femur

Correct Answer & Explanation

. Preoperative selective arterial embolization of the lesion

Explanation

Metastatic lesions from renal cell carcinoma (RCC) and thyroid carcinoma are notoriously hypervascular. Surgical intervention, such as curettage or intramedullary nailing, carries a high risk of massive, life-threatening hemorrhage. Preoperative selective arterial embolization is strongly recommended 24-48 hours prior to surgery to minimize intraoperative blood loss.

Question 4325

Topic: 10. Pathology and Oncology

A 50-year-old male presents with polyneuropathy, generalized edema, new-onset diabetes mellitus, and skin hyperpigmentation. A skeletal survey demonstrates multiple osteosclerotic lesions rather than typical 'punched-out' lytic lesions. This specific constellation of clinical findings is most classically associated with which underlying pathology?

. Monoclonal plasma cell proliferative disorder
. Metastatic breast carcinoma
. Metastatic prostate carcinoma
. Langerhans cell histiocytosis
. Eosinophilic granulomatosis

Correct Answer & Explanation

. Monoclonal plasma cell proliferative disorder

Explanation

The vignette describes POEMS syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy, and Skin changes). POEMS syndrome is uniquely associated with a variant of plasma cell dyscrasia (monoclonal plasma cell proliferative disorder), most notably osteosclerotic myeloma, where the bone lesions are sclerotic rather than the classic lytic lesions seen in standard multiple myeloma.

Question 4326

Topic: 10. Pathology and Oncology

A 35-year-old male presents with multi-centric, well-defined osteolytic lesions distributed throughout the bones of his right lower extremity (femur, tibia, and talus).

Biopsy of the tibial lesion reveals interconnecting cords and nests of plump, epithelioid cells with intracytoplasmic vacuoles containing erythrocytes, strongly positive for CD31 and ERG. What is the most likely diagnosis?

. Metastatic melanoma
. Epithelioid hemangioendothelioma
. Enchondromatosis (Ollier disease)
. Kaposi sarcoma
. Bacillary angiomatosis

Correct Answer & Explanation

. Epithelioid hemangioendothelioma

Explanation

Epithelioid hemangioendothelioma is a low-to-intermediate grade vascular tumor. A classic and highly characteristic presentation of vascular tumors of bone (like hemangioma, hemangioendothelioma, or angiosarcoma) is regional multicentricity—multiple lesions clustering within the bones of a single anatomic region or extremity. Histologically, it forms vascular channels lined by plump epithelioid endothelial cells, which are positive for vascular markers like CD31, CD34, and ERG.

Question 4327

Topic: Bone Tumors

An 18-year-old male presents with severe, progressive back pain that worsens at night and is dramatically relieved by naproxen. He has recently developed a painful scoliosis. CT imaging identifies a 1.0 cm radiolucent nidus surrounded by dense reactive sclerosis in the right posterior elements of the T8 vertebra. Regarding the resultant spinal deformity, which statement is most accurate?

. The lesion is typically located on the concavity of the scoliotic curve.
. The lesion is typically located on the convexity of the scoliotic curve.
. The lesion is typically located at the exact apex of the convexity.
. The curvature varies randomly and shows no consistent relationship to the lesion side.
. The resultant scoliosis is always non-structural and purely compensatory for leg length inequality.

Correct Answer & Explanation

. The lesion is typically located on the concavity of the scoliotic curve.

Explanation

The patient has an osteoid osteoma of the spine. When an osteoid osteoma arises in the spine, it predominantly affects the posterior elements (lamina, pedicle). The severe pain causes asymmetric muscle spasm, leading to a scoliotic deformity. Classically, the resulting curve is rigid, and the tumor nidus is found on the concavity of the curve due to the intense local muscle spasm.

Question 4328

Topic: Bone Tumors

A 9-year-old boy sustains a proximal humerus fracture after a minor fall. Radiographs demonstrate a fracture through a large, centrally located, radiolucent lesion in the metaphysis that mildly expands the bone. A small fragment of cortical bone is visible resting at the dependent (bottom) portion of the radiolucent cavity.

What is this characteristic radiographic sign called?

. Sunburst sign
. Fallen leaf sign
. Shepherd's crook deformity
. Corduroy sign
. Blade of grass sign

Correct Answer & Explanation

. Fallen leaf sign

Explanation

The 'fallen leaf' or 'fallen fragment' sign is pathognomonic for a Simple Bone Cyst (Unicameral Bone Cyst). Because the cyst is fluid-filled and lacks a solid matrix, a fractured fragment of cortex can fall freely through the fluid to rest at the dependent portion of the cavity. If the cyst were a solid tumor (like an enchondroma or fibrous dysplasia), the fragment would remain suspended in place.

Question 4329

Topic: 10. Pathology and Oncology

A 45-year-old male presents with chronic knee pain and a sensation of multiple loose bodies 'catching' in the joint. Radiographs show dozens of uniformly sized, calcified nodules confined to the joint space. A synovial biopsy confirms primary synovial chondromatosis. Which of the following best represents the approximate lifetime risk of malignant transformation of this primary condition to chondrosarcoma?

. Less than 1%
. 5%
. 15%
. 25%
. 50%

Correct Answer & Explanation

. 5%

Explanation

Primary synovial chondromatosis is a benign neoplastic process of the synovium resulting in multiple intra-articular cartilaginous loose bodies. Although benign, it has a well-documented risk of malignant transformation into secondary synovial chondrosarcoma. The universally cited textbook rate for this malignant transformation is approximately 5%.

Question 4330

Topic: 10. Pathology and Oncology

A 16-year-old female presents with knee pain. MRI reveals a rapidly expanding, eccentric, purely lytic lesion in the distal femur metaphysis demonstrating multiple fluid-fluid levels.

A core biopsy confirms the diagnosis of a primary Aneurysmal Bone Cyst (ABC). The pathogenesis of a primary ABC is most strongly driven by a recurrent chromosomal translocation resulting in the upregulation of which gene?

. EWS
. MDM2
. USP6
. H3F3A
. EXT1

Correct Answer & Explanation

. USP6

Explanation

Primary Aneurysmal Bone Cysts (ABCs) are genuine neoplasms (not just reactive phenomena) driven by recurrent translocations, most commonly t(16;17)(q22;p13), which places the USP6 gene promoter under the control of highly active promoters like CDH11. This leads to the upregulation of USP6. MDM2 is associated with atypical lipomatous tumors and parosteal osteosarcoma; H3F3A with giant cell tumors; EXT1 with osteochondromas; and EWS with Ewing Sarcoma.

Question 4331

Topic: 10. Pathology and Oncology

A 60-year-old male presents with a permeative, destructive lesion in the diaphyseal marrow cavity of his femur. Biopsy reveals sheets of large, atypical lymphoid cells with prominent nucleoli. The cells strongly express CD20 and CD45, and lack CD99 expression. Which of the following special stains will most characteristically demonstrate a network of fibers wrapping around individual tumor cells, aiding in differentiating this entity from Ewing sarcoma?

. Periodic Acid-Schiff (PAS)
. Reticulin stain
. Fontana-Masson
. Congo Red
. Masson Trichrome

Correct Answer & Explanation

. Reticulin stain

Explanation

Primary bone lymphoma (typically Diffuse Large B-Cell Lymphoma, expressing CD20/CD45) can radiographically and histologically mimic Ewing sarcoma. Ewing sarcoma expresses CD99 and is strongly PAS positive (due to intracellular glycogen). A defining histologic feature visible on special stains is that reticulin fibers surroundindividualtumor cells in lymphoma, whereas in Ewing sarcoma (and other carcinomas), reticulin fibers surroundnestsor clusters of cells, rather than individual cells.

Question 4332

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with painless anterior bowing of the tibia. Radiographs demonstrate a multiloculated, expansile, osteolytic lesion confined to the anterior cortex of the tibial diaphysis. Biopsy reveals fibrous tissue interspersed with trabeculae of woven bone ringed by plump osteoblasts, consistent with Osteofibrous Dysplasia (Campanacci disease). What is the primary reason that wide resection or very close observation is mandated for this condition?

. It has a near 100% risk of pathological fracture requiring prophylactic nailing.
. It is strongly associated with Neurofibromatosis Type 1 (NF1).
. It shares a close histogenetic relationship with, and may coexist with or progress to, Adamantinoma.
. It carries a high risk of rapid, fatal lung metastasis.
. It undergoes spontaneous malignant transformation to osteosarcoma during adolescence.

Correct Answer & Explanation

. It shares a close histogenetic relationship with, and may coexist with or progress to, Adamantinoma.

Explanation

Osteofibrous dysplasia (OFD) is a rare fibro-osseous lesion of childhood that predominantly affects the anterior cortex of the tibia. It is critically important because it is considered a precursor to, or part of a spectrum with, Adamantinoma. Because small foci of adamantinoma may coexist within a lesion that is otherwise indistinguishable from OFD, biopsy requires extensive sampling, and some authorities recommend wide resection for larger lesions to avoid missing a diagnosis of adamantinoma.

Question 4333

Topic: 10. Pathology and Oncology

A 22-year-old female presents with a bone tumor on the anterior surface of the mid-tibial diaphysis. The surgeon is differentiating between parosteal osteosarcoma and periosteal osteosarcoma. Which of the following characteristics is most strictly associated with periosteal osteosarcoma compared to parosteal osteosarcoma?

. It is typically a low-grade, predominantly fibro-osseous lesion.
. It is an intermediate-grade lesion with a predominantly chondroblastic matrix.
. It typically occurs on the posterior aspect of the distal femur.
. It has a significantly lower risk of metastasis.
. It is characterized molecularly by consistent MDM2 and CDK4 amplification.

Correct Answer & Explanation

. It typically occurs on the posterior aspect of the distal femur.

Explanation

Periosteal osteosarcoma is an intermediate-grade surface osteosarcoma that typically arises on the anterior surface of the tibial diaphysis and has a predominantly chondroblastic matrix. In contrast, parosteal osteosarcoma is a low-grade surface tumor that typically arises on the posterior aspect of the distal femur metaphysis, has a predominantly fibro-osseous matrix, and is defined by MDM2/CDK4 amplification. Periosteal osteosarcoma has a higher risk of metastasis than parosteal, but lower than conventional intramedullary osteosarcoma.

Question 4334

Topic: 10. Pathology and Oncology

A 14-year-old patient is diagnosed with localized, high-grade osteosarcoma of the distal femur. Following wide surgical resection and reconstruction, the pathology report is reviewed. What is the single most significant prognostic factor for this patient's long-term overall survival?

. Tumor volume at the time of initial presentation
. Histologic subtype of the osteosarcoma (e.g., osteoblastic vs. chondroblastic)
. The width of the surgical margins achieved
. Patient age and gender at diagnosis
. Percentage of tumor necrosis following neoadjuvant chemotherapy

Correct Answer & Explanation

. Tumor volume at the time of initial presentation

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the single most important prognostic indicator for overall survival in patients with localized, high-grade osteosarcoma. A good response is typically defined as greater than 90% tumor necrosis.

Question 4335

Topic: Bone Tumors

A 65-year-old female presents with progressive back pain and fatigue. Radiographs demonstrate multiple 'punched-out' lytic lesions in her skull and lumbar vertebral bodies without a sclerotic rim. Laboratory analysis reveals hypercalcemia, anemia, and an elevated serum creatinine. The primary neoplastic cells involved in this disease process are derived from which of the following cellular lineages?

. Osteoblasts
. Chondrocytes
. T-lymphocytes
. Macrophages
. B-lymphocytes (Plasma cells)

Correct Answer & Explanation

. B-lymphocytes (Plasma cells)

Explanation

The clinical presentation (CRAB criteria: Calcium elevation, Renal insufficiency, Anemia, Bone lesions) and radiographic findings are classic for Multiple Myeloma, the most common primary malignancy of bone in adults. It is characterized by the neoplastic clonal proliferation of plasma cells, which are terminally differentiated B-lymphocytes.

Question 4336

Topic: 10. Pathology and Oncology

A 15-year-old male presents with a painful mass around his right knee. Radiographs reveal a sunburst periosteal reaction in the distal femur. Biopsy confirms high-grade osteosarcoma. Which of the following genetic syndromes is most strongly associated with an increased risk of developing this specific primary bone tumor?

. Rothmund-Thomson syndrome (RECQL4 mutation)
. Multiple Hereditary Exostoses (EXT1 mutation)
. Fibrous Dysplasia (GNAS1 mutation)
. Neurofibromatosis type 1 (NF1 mutation)
. Osteogenesis Imperfecta (COL1A1 mutation)

Correct Answer & Explanation

. Rothmund-Thomson syndrome (RECQL4 mutation)

Explanation

Osteosarcoma is strongly associated with retinoblastoma (Rb gene), Li-Fraumeni syndrome (p53 mutation), and Rothmund-Thomson syndrome (RECQL4 helicase mutation). EXT1 is associated with osteochondromas and secondary chondrosarcoma. GNAS1 is seen in fibrous dysplasia and McCune-Albright syndrome. NF1 is associated with malignant peripheral nerve sheath tumors.

Question 4337

Topic: 10. Pathology and Oncology

A patient undergoing an orthopedic procedure under general anesthesia develops generalized muscle rigidity, tachycardia, and a rapid rise in core body temperature. The underlying pathophysiology of this life-threatening event involves a genetic mutation in which of the following?

. Nicotinic acetylcholine receptor
. Ryanodine receptor (RYR1)
. Dihydropyridine (DHP) receptor
. GABAA receptor
. Voltage-gated sodium channel

Correct Answer & Explanation

. Nicotinic acetylcholine receptor

Explanation

Malignant hyperthermia is an autosomal dominant pharmacogenetic disorder most commonly caused by a mutation in the Ryanodine receptor 1 (RYR1) gene on chromosome 19. Exposure to triggering agents causes massive, uncontrolled calcium release from the sarcoplasmic reticulum.

Question 4338

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful, permeative diaphyseal lesion in his femur with an associated soft tissue mass. Biopsy confirms small blue round cells. Which of the following genetic translocations is most pathognomonic for this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22) translocation, leading to the EWS-FLI1 fusion protein. Synovial sarcoma is associated with t(X;18), and alveolar rhabdomyosarcoma with t(2;13).

Question 4339

Topic: Bone Tumors

A 65-year-old male presents with a pathologic fracture of the proximal humerus. Radiographs show a distinct "punched-out" lytic lesion. Laboratory tests reveal an M-spike on serum protein electrophoresis. Which of the following imaging modalities is the most appropriate next step for staging the skeletal extent of this disease?

. Technetium-99m bone scan
. Whole-body low-dose CT or skeletal survey
. Gallium-67 scan
. Indium-111 WBC scan
. Ultrasound of the long bones

Correct Answer & Explanation

. Technetium-99m bone scan

Explanation

Whole-body low-dose CT is now the standard for staging the skeletal involvement of multiple myeloma, replacing the traditional radiographic skeletal survey. Technetium-99m bone scans rely on osteoblastic activity and often produce false negatives in purely lytic myeloma lesions.

Question 4340

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with thigh pain and a low-grade fever. Radiographs reveal a permeative diaphyseal lesion in the femur with a laminated periosteal reaction. A biopsy shows small round blue cells. Which of the following chromosomal translocations is most strongly associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and histologic picture describes Ewing sarcoma, classically presenting as a permeative diaphyseal lesion with small round blue cells. It is strongly associated with the t(11;22) chromosomal translocation, resulting in the EWS-FLI1 fusion protein.

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