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10. Pathology and Oncology MCQs

Practice Set 330 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 6581

Topic: 10. Pathology and Oncology

A 16-year-old girl is diagnosed with high-grade osteosarcoma of the distal femur. She completes neoadjuvant chemotherapy and undergoes wide surgical resection. What is the most important prognostic factor for her long-term survival?

. The specific anatomic location of the tumor
. The histological subtype of the tumor
. The percentage of tumor necrosis following neoadjuvant chemotherapy
. The size of the tumor at initial presentation
. The presence of a pathological fracture

Correct Answer & Explanation

. The percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

In high-grade osteosarcoma, the degree of tumor necrosis (>90% is considered a good response) following neoadjuvant chemotherapy is the single most important prognostic indicator for long-term survival.

Question 6582

Topic: Bone Tumors

A 19-year-old male presents with painful scoliosis and back pain that is poorly relieved by NSAIDs. Imaging reveals a 2.5 cm radiolucent lesion in the posterior elements of L3 with a mineralized center. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Eosinophilic granuloma
. Osteosarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

The presentation of a painful, bone-forming lesion in the posterior spinal elements is typical for osteoblastoma or osteoid osteoma. A size greater than 2.0 cm generally distinguishes an osteoblastoma from an osteoid osteoma, and the pain is often less responsive to NSAIDs.

Question 6583

Topic: 10. Pathology and Oncology

A 65-year-old man presents with severe lower back pain and fatigue. Radiographs reveal diffuse osteopenia and multiple punched-out lytic lesions in the skull and spine.

Which of the following is the most likely cause of false-negative technetium-99m bone scans in this condition?

. Excessive osteoid production by malignant cells
. Absence of reactive osteoblastic activity
. Extremely rapid bone turnover overriding the tracer
. High vascularity of the lesions washing out the isotope
. Systemic inhibition of osteoclastogenesis

Correct Answer & Explanation

. Absence of reactive osteoblastic activity

Explanation

Multiple myeloma lesions are purely lytic and characteristically lack reactive osteoblastic activity due to the secretion of factors like Dkk-1 by myeloma cells, which inhibits osteoblasts. Thus, technetium-99m bone scans, which rely on osteoblastic activity for tracer uptake, are often false-negative.

Question 6584

Topic: 10. Pathology and Oncology

A 62-year-old female presents with hypercalcemia, anemia, and acute renal failure. A skeletal survey reveals multiple osteolytic lesions.

Which of the following describes the characteristic histological finding of the primary neoplastic cells in this disease?

. Small blue cells with scant cytoplasm forming rosettes
. Spindle cells arranged in a classic herringbone pattern
. Plasma cells with clock-face nuclei and perinuclear clearing
. Multinucleated giant cells within a stroma of mononuclear cells
. Large pleomorphic cells producing malignant osteoid

Correct Answer & Explanation

. Plasma cells with clock-face nuclei and perinuclear clearing

Explanation

Multiple myeloma is characterized by the malignant proliferation of plasma cells in the bone marrow. These cells typically display eccentric, 'clock-face' nuclei and a prominent perinuclear halo representing the Golgi apparatus.

Question 6585

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with progressive knee pain. Imaging reveals an eccentric, purely lytic lesion in the distal femoral epiphysis extending into the metaphysis. Biopsy confirms Giant Cell Tumor of bone. What is the mechanism of action of the targeted medical therapy most commonly used for unresectable cases?

. Direct cytotoxicity to the multinucleated giant cells
. Inhibition of RANK-L, preventing osteoclast-like giant cell formation
. Inhibition of VEGF, decreasing tumor angiogenesis and blood supply
. Cross-linking of DNA leading to neoplastic cell apoptosis
. Activation of local osteoblasts to induce intralesional ossification

Correct Answer & Explanation

. Inhibition of RANK-L, preventing osteoclast-like giant cell formation

Explanation

Denosumab is a monoclonal antibody that binds RANK-L, preventing its interaction with RANK receptors. In Giant Cell Tumor, the neoplastic mononuclear cells overexpress RANK-L, which drives the recruitment of the destructive, reactive osteoclast-like giant cells.

Question 6586

Topic: Bone Tumors

A 68-year-old man presents with severe back pain and fatigue. Radiographs demonstrate diffuse osteopenia and multiple punched-out lytic lesions in the skull and vertebral bodies.

Which of the following is the most sensitive test to establish the diagnosis?

. Bone scintigraphy
. Serum and urine protein electrophoresis
. Erythrocyte sedimentation rate
. Alkaline phosphatase
. C-reactive protein

Correct Answer & Explanation

. Serum and urine protein electrophoresis

Explanation

Serum and urine protein electrophoresis (SPEP/UPEP) with immunofixation are the most sensitive initial tests for Multiple Myeloma, detecting monoclonal proteins. Bone scintigraphy is often cold (negative) because myeloma suppresses osteoblast activity.

Question 6587

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a rapidly enlarging mass over his proximal tibia. MRI demonstrates an eccentric metaphyseal lesion with multiple fluid-fluid levels. Biopsy confirms an aneurysmal bone cyst (ABC). What is the most common cytogenetic abnormality associated with primary ABC?

. t(11;22) translocation
. t(X;18) translocation
. USP6 (17p13) gene rearrangement
. MDM2 amplification
. GNAS mutation

Correct Answer & Explanation

. USP6 (17p13) gene rearrangement

Explanation

Primary aneurysmal bone cysts are true neoplasms driven by a USP6 gene rearrangement on chromosome 17p13. Fluid-fluid levels are characteristic on MRI due to blood products separating by density.

Question 6588

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful mass near his knee. Radiographs reveal a metaphyseal lesion with a sunburst pattern of periosteal reaction and a Codman triangle. A biopsy confirms conventional osteosarcoma. What is the standard treatment protocol for this patient?

. Immediate amputation
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Wide surgical resection followed by radiation therapy
. Radiation therapy as primary monotherapy
. Intralesional curettage with liquid nitrogen cryotherapy

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

The standard of care for conventional high-grade osteosarcoma is neoadjuvant chemotherapy, followed by wide surgical resection (limb-salvage or amputation), and completed with adjuvant chemotherapy. Radiation therapy is typically not utilized as osteosarcoma is relatively radioresistant.

Question 6589

Topic: Bone Tumors

A 65-year-old male presents with deep bone pain in his lower back and ribs. Laboratory results show hypercalcemia and normocytic anemia. Radiographs reveal multiple "punched-out" lytic lesions in the skull and axial skeleton.

Which of the following is the most appropriate initial diagnostic test to confirm the underlying etiology?

. Alkaline phosphatase level
. Prostate-specific antigen (PSA)
. Serum protein electrophoresis (SPEP)
. Erythrocyte sedimentation rate (ESR)
. C-reactive protein (CRP)

Correct Answer & Explanation

. Serum protein electrophoresis (SPEP)

Explanation

The clinical presentation and "punched-out" lytic lesions are classic for Multiple Myeloma. SPEP and UPEP are the most appropriate initial tests, revealing a monoclonal spike (M-protein) in the majority of patients. It is the most common primary bone malignancy in adults.

Question 6590

Topic: 10. Pathology and Oncology

A 60-year-old female with known multiple myeloma presents with thigh pain. Radiographs reveal a purely lytic lesion in the subtrochanteric femur occupying 50% of the cortical diameter. She describes moderate pain with weight-bearing. Using the Mirels' criteria, what is the appropriate management?

. Observation and protected weight-bearing
. Radiotherapy alone
. Prophylactic internal fixation followed by radiotherapy
. Bisphosphonate therapy alone
. Chemotherapy adjustment only

Correct Answer & Explanation

. Prophylactic internal fixation followed by radiotherapy

Explanation

The Mirels' score for this lesion is 10: Site (lower limb = 3), Pain (moderate = 2), Lesion type (lytic = 3), Size (1/3 to 2/3 = 2). A score of 9 or greater indicates impending fracture and warrants prophylactic internal fixation, typically followed by radiotherapy.

Question 6591

Topic: Bone Tumors

A 45-year-old male presents with polyneuropathy, organomegaly, endocrinopathy, an M-protein spike, and skin changes. Skeletal survey reveals predominantly osteosclerotic bone lesions. What is the most likely diagnosis?

. Multiple Myeloma
. Waldenstrom's Macroglobulinemia
. POEMS Syndrome
. Osteosarcoma
. Paget's Disease of Bone

Correct Answer & Explanation

. POEMS Syndrome

Explanation

POEMS syndrome is a rare paraneoplastic disorder secondary to a plasma cell dyscrasia. The acronym stands for Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, and Skin changes. Unlike classic multiple myeloma, the bone lesions in POEMS syndrome are predominantly osteosclerotic.

Question 6592

Topic: 10. Pathology and Oncology

A 50-year-old patient is diagnosed with a solitary plasmacytoma of the L2 vertebral body. Systemic workup, including bone marrow biopsy and skeletal survey, is negative. What is the standard definitive treatment for this isolated lesion?

. Definitive local radiotherapy
. Systemic chemotherapy and autologous stem cell transplant
. En bloc surgical resection
. Intravenous bisphosphonates indefinitely
. Observation with serial MRI

Correct Answer & Explanation

. Definitive local radiotherapy

Explanation

The standard of care for a solitary plasmacytoma of bone is definitive local radiotherapy, as these lesions are highly radiosensitive. Surgery is reserved for structural instability or rapid neurological deterioration. Lifelong monitoring is required due to a high rate of progression to multiple myeloma.

Question 6593

Topic: Bone Tumors

A patient with multiple myeloma develops progressive acute kidney injury. Which of the following is the most common pathophysiologic cause of renal failure in these patients?

. Hyperuricemia leading to urate nephropathy
. Precipitation of free light chains in the distal renal tubules
. Direct infiltration of the renal parenchyma by plasma cells
. NSAID-induced interstitial nephritis
. Amyloid deposition in the renal glomeruli

Correct Answer & Explanation

. Precipitation of free light chains in the distal renal tubules

Explanation

Cast nephropathy (myeloma kidney) is the most common cause of renal failure in multiple myeloma. It is caused by the precipitation of monoclonal free light chains (Bence Jones proteins) with Tamm-Horsfall proteins in the distal convoluted tubules, forming obstructing casts. This leads to tubular damage and obstruction.

Question 6594

Topic: 10. Pathology and Oncology

A 68-year-old male undergoes prophylactic intramedullary nailing for a large, painful lytic lesion in the diaphysis of the femur caused by multiple myeloma. Which of the following is the most appropriate next step in local management?

. Initiate aggressive physical therapy alone
. Immediate hardware removal once fracture callus forms
. Systemic antibiotics for 6 weeks
. Postoperative external beam radiation therapy
. Pulsed electromagnetic field therapy

Correct Answer & Explanation

. Postoperative external beam radiation therapy

Explanation

Following prophylactic fixation of an impending pathologic fracture due to multiple myeloma (or metastatic disease), postoperative external beam radiation therapy is required. Radiation provides local tumor control, halts continued bone destruction, and alleviates pain. Healing of the defect requires local tumor eradication.

Question 6595

Topic: 10. Pathology and Oncology

A 25-year-old female presents with an asymmetric, painful, sclerotic thickening of her right tibial diaphysis. The condition began after puberty. Biopsy shows normal bone remodeling with no malignant cells. What is the most likely diagnosis?

. Camurati-Engelmann disease
. Ribbing disease
. Osteosarcoma
. Eosinophilic granuloma
. Fibrous dysplasia

Correct Answer & Explanation

. Ribbing disease

Explanation

Ribbing disease (multiple diaphyseal sclerosis) presents after puberty with asymmetric, painful diaphyseal sclerosis. This contrasts with Camurati-Engelmann disease, which presents in childhood and is typically symmetric. Both conditions affect the diaphyses but differ in onset and symmetry.

Question 6596

Topic: Bone Tumors

When evaluating a patient with newly diagnosed Multiple Myeloma, which imaging modality is historically notorious for yielding falsely negative results when screening for bone lesions?

. Whole-body MRI
. Low-dose Whole-body CT
. Conventional skeletal survey
. Positron Emission Tomography (PET-CT)
. Technetium-99m bone scan

Correct Answer & Explanation

. Technetium-99m bone scan

Explanation

Technetium-99m bone scans rely on osteoblastic activity (bone formation) to show uptake. Multiple myeloma lesions are purely osteolytic, mediated by uncoupled osteoclastic activity with suppressed osteoblastic function. Therefore, bone scans are often falsely negative ("cold") in multiple myeloma.

Question 6597

Topic: 10. Pathology and Oncology

What is the primary cellular abnormality observed in the bone marrow biopsy of a patient with Multiple Myeloma?

. Proliferation of atypical plasma cells with eccentric nuclei and "clock-face" chromatin
. Presence of Reed-Sternberg cells
. Small round blue cells with Homer-Wright rosettes
. Spindle cells arranged in a herringbone pattern
. Multinucleated giant cells in a background of mononuclear stromal cells

Correct Answer & Explanation

. Proliferation of atypical plasma cells with eccentric nuclei and "clock-face" chromatin

Explanation

Multiple myeloma is a clonal proliferation of malignant plasma cells. On histology, these cells have eccentric nuclei, coarse "clock-face" or "cartwheel" chromatin, and a perinuclear halo. Intracytoplasmic inclusions of immunoglobulins (Russell bodies) or Mott cells may also be seen.

Question 6598

Topic: Bone Tumors

A 62-year-old man is suspected of having multiple myeloma after routine lab work shows elevated total protein with normal serum albumin. Which of the following imaging modalities is considered the most sensitive for detecting early osteolytic skeletal involvement and extramedullary disease in this patient?

. Technetium-99m bone scintigraphy
. Plain radiography skeletal survey
. Whole-body MRI
. Dual-energy X-ray absorptiometry (DEXA)
. Quantitative computed tomography (qCT)

Correct Answer & Explanation

. Whole-body MRI

Explanation

Whole-body MRI (and PET/CT) is significantly more sensitive than a plain radiographic skeletal survey for detecting early bone marrow involvement and extramedullary lesions in multiple myeloma. Technetium-99m bone scans are highly insensitive for myeloma because the lesions typically lack an osteoblastic response.

Question 6599

Topic: Bone Tumors
A 14-year-old girl presents with a Shepherd's crook deformity of her proximal femur and irregularly bordered café-au-lait macules on her trunk. What is the underlying genetic and molecular mechanism of her disease?
. Inactivating mutation in EXT1 leading to disrupted heparan sulfate synthesis
. Activating mutation in GNAS leading to continuous production of cAMP
. Mutation in COL1A1 leading to defective type I collagen synthesis
. Inactivating mutation in RB1 leading to unchecked cellular proliferation
. Activating mutation in FGFR3 leading to inhibited chondrocyte proliferation

Correct Answer & Explanation

. Activating mutation in GNAS leading to continuous production of cAMP

Explanation

This patient has McCune-Albright syndrome, a severe form of polyostotic fibrous dysplasia. It is caused by a post-zygotic activating somatic mutation in the GNAS gene, which encodes the alpha subunit of the stimulatory G protein (Gs), resulting in continuous, unregulated production of intracellular cAMP.

Question 6600

Topic: 10. Pathology and Oncology

A 65-year-old female with a known history of multiple myeloma presents with increasing pain in her right thigh when walking. Radiographs show a 3.5 cm lytic lesion in the proximal diaphyseal region of the right femur involving 60% of the cortical diameter. Her Mirels score is 10. What is the most appropriate management?

. Immediate initiation of localized external beam radiation therapy only
. Protected weight-bearing and systemic chemotherapy
. Prophylactic intramedullary nailing followed by radiation therapy
. Core decompression of the lesion with bone grafting
. En bloc resection and massive structural allograft reconstruction

Correct Answer & Explanation

. Prophylactic intramedullary nailing followed by radiation therapy

Explanation

A Mirels score of 9 or greater indicates a high risk for impending pathologic fracture. The standard of care for a high-risk diaphyseal impending fracture in multiple myeloma is prophylactic stabilization (e.g., intramedullary nailing) to prevent fracture, followed by postoperative radiation for local tumor control.

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