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10. Pathology and Oncology MCQs

Practice Set 139 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 2761

Topic: Bone Tumors

A 14-year-old girl sustains a minor fall and reports persistent shoulder pain. Radiographs of the proximal humerus show a central, purely lytic lesion with cortical thinning. A 'fallen leaf' sign is noted. A needle is advanced into the lesion for aspiration and injection. What type of fluid is typically aspirated from this cyst?

. Serosanguineous fluid with extremely high alkaline phosphatase
. Clear yellow fluid with high levels of prostaglandins
. Pure venous blood under pulsatile pressure
. Purulent fluid with a high leukocyte count
. Viscous mucin with high hyaluronic acid content

Correct Answer & Explanation

. Clear yellow fluid with high levels of prostaglandins

Explanation

The clinical presentation and 'fallen leaf' (or fallen fragment) sign are pathognomonic for a unicameral bone cyst (UBC) or simple bone cyst, which has fractured. Fluid aspirated from an active UBC is typically clear or straw-colored (yellowish) and contains highly elevated levels of prostaglandins, particularly PGE2, which are believed to contribute to cyst expansion by stimulating bone resorption. Aneurysmal bone cysts typically yield dark blood under moderate pressure.

Question 2762

Topic: 10. Pathology and Oncology

A 60-year-old man presents with persistent sacral pain, recent-onset bowel and bladder dysfunction, and a palpable pre-sacral soft-tissue mass. Imaging demonstrates a destructive, midline sacral lesion with a large anterior soft tissue component. Histopathologic examination of the biopsy reveals lobules of vacuolated cells with bubbly cytoplasm set in a myxoid stroma. Which of the following immunohistochemical markers is most highly specific for this tumor?

. S-100
. Cytokeratin
. Brachyury
. Epithelial Membrane Antigen (EMA)
. Smooth Muscle Actin (SMA)

Correct Answer & Explanation

. Brachyury

Explanation

The tumor described is a chordoma, which characteristically arises in the midline axis (most commonly sacrococcygeal or spheno-occipital). Histologically, it features physaliferous ('bubbly') cells in an abundant myxoid stroma. Chordomas arise from notochord remnants. Brachyury is a transcription factor specific to notochordal differentiation and is the most sensitive and specific immunohistochemical marker for distinguishing chordoma from other myxoid or epithelial tumors (like myxoid chondrosarcoma or metastatic carcinoma).

Question 2763

Topic: 10. Pathology and Oncology

A 45-year-old woman is evaluated for a slowly enlarging, painless mass in the deep posterior compartment of her thigh. MRI reveals a well-circumscribed, lobulated mass with heterogeneous high T2 signal and a 'triple signal' pattern. Biopsy shows a biphasic tumor containing both epithelial (glandular) and spindle cell components. Which of the following cytogenetic abnormalities is diagnostic for this tumor?

. t(11;22) (q24;q12)
. t(X;18) (p11;q11)
. t(12;16) (q13;p11)
. t(2;13) (q35;q14)
. t(9;22) (q22;q12)

Correct Answer & Explanation

. t(X;18) (p11;q11)

Explanation

The diagnosis is synovial sarcoma, which frequently presents as a slow-growing, deep-seated soft tissue mass in the lower extremities of young to middle-aged adults. It can present with a biphasic histologic pattern (epithelial and spindle cells) or a monophasic spindle cell pattern. It is genetically characterized by the t(X;18)(p11;q11) translocation, creating the pathognomonic SS18-SSX fusion gene. t(12;16) is seen in myxoid liposarcoma, t(2;13) in alveolar rhabdomyosarcoma, and t(9;22) in extraskeletal myxoid chondrosarcoma.

Question 2764

Topic: 10. Pathology and Oncology

A 68-year-old man presents with severe generalized lower back pain, persistent fatigue, and recurrent respiratory infections. Laboratory testing reveals normocytic anemia, hypercalcemia, and an elevated serum creatinine. Radiographs of the spine and skull demonstrate multiple 'punched-out' lytic lesions lacking reactive sclerotic margins. A bone marrow aspirate and biopsy are most likely to show an abnormal, clonal proliferation of which of the following cell types?

. Mononuclear osteoclast precursors
. Plasma cells
. Myeloblasts
. Reed-Sternberg cells
. Lymphoblasts

Correct Answer & Explanation

. Plasma cells

Explanation

The clinical presentation of anemia, hypercalcemia, renal failure, and punched-out lytic bone lesions is the hallmark of multiple myeloma (CRAB criteria). The diagnosis of multiple myeloma is confirmed by demonstrating greater than 10% clonal plasma cells on a bone marrow biopsy or the presence of a biopsy-proven plasmacytoma, typically accompanied by monoclonal proteins in the serum or urine (M-spike).

Question 2765

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain and a mixed lytic/sclerotic lesion in the metaphysis of the distal femur. Biopsy confirms high-grade osteosarcoma. Which of the following genetic alterations is most strongly associated with the pathogenesis of this disease?

. t(11;22)(q24;q12) chromosomal translocation
. Mutation of the p53 tumor suppressor gene
. t(X;18)(p11;q11) chromosomal translocation
. Activating mutation of the GNAS gene
. Inactivating mutation of the EXT1 gene

Correct Answer & Explanation

. Mutation of the p53 tumor suppressor gene

Explanation

Osteosarcoma is frequently associated with mutations in tumor suppressor genes, particularly p53 (associated with Li-Fraumeni syndrome) and Rb (associated with Retinoblastoma). The t(11;22) translocation is characteristic of Ewing sarcoma; t(X;18) is pathognomonic for synovial sarcoma; GNAS mutations are seen in fibrous dysplasia; and EXT1 gene mutations are the cause of multiple hereditary exostoses.

Question 2766

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with fever, weight loss, and mid-thigh pain. Imaging shows a permeative, diaphyseal lesion with an 'onion-skin' periosteal reaction. Histology reveals sheets of small, round blue cells that stain strongly positive for CD99. What represents the most significant prognostic factor for overall survival in this patient?

. Presence of metastases at the time of diagnosis
. Histologic grade of the tumor
. Tumor size greater than 5 cm
. Age of the patient at presentation
. Extent of periosteal reaction on initial radiographs

Correct Answer & Explanation

. Presence of metastases at the time of diagnosis

Explanation

The patient has Ewing sarcoma, characterized by classic small round blue cells, CD99 positivity, and a typical diaphyseal location. The most critical prognostic factor for overall survival in Ewing sarcoma is the presence of distant metastases at the time of diagnosis, which drops survival rates significantly. Because all Ewing sarcomas are considered high-grade tumors by definition, histologic grade is not a variable prognostic factor.

Question 2767

Topic: 10. Pathology and Oncology

A 24-year-old man sustains a pathological fracture of the proximal femur. Radiographs prior to the fracture revealed a well-circumscribed, intramedullary lesion with a 'ground-glass' appearance and a 'shepherd's crook' deformity. A biopsy demonstrates irregular trabeculae of woven bone without prominent osteoblastic rimming in a fibrous stroma. Which of the following best describes the underlying molecular pathogenesis of this condition?

. Activating mutation in the GNAS gene leading to increased intracellular cAMP
. Inactivating mutation in the EXT1 gene causing disordered endochondral ossification
. Overexpression of the MDM2 and CDK4 genes
. Somatic mutation in the IDH1 or IDH2 gene
. Defect in type I collagen synthesis due to a COL1A1 mutation

Correct Answer & Explanation

. Activating mutation in the GNAS gene leading to increased intracellular cAMP

Explanation

The clinical and radiographic presentation is classic for fibrous dysplasia. The underlying pathophysiology involves a somatic, activating missense mutation in the GNAS gene, which encodes the alpha subunit of the stimulatory G-protein (Gs-alpha). This mutation leads to constitutive activation of adenylate cyclase, resulting in elevated intracellular cyclic AMP (cAMP) levels that cause abnormal proliferation and differentiation of bone marrow stromal cells.

Question 2768

Topic: 10. Pathology and Oncology

A 19-year-old male complains of severe, right-sided thigh pain that worsens at night and is characteristically relieved by ibuprofen within 30 minutes. Plain radiographs of the femur show a 1-cm radiolucent nidus surrounded by dense reactive sclerosis in the diaphyseal cortex. Which of the following is most accurate regarding the pathophysiology and characteristics of this lesion?

. The nidus typically exceeds 2 cm in diameter
. The pain is mediated by high local concentrations of prostaglandins
. The lesion has a high propensity for malignant transformation
. It usually requires wide en bloc resection to prevent local recurrence
. Histology shows atypical, pleomorphic osteoblasts with frequent mitoses

Correct Answer & Explanation

. The pain is mediated by high local concentrations of prostaglandins

Explanation

The presentation is classic for an osteoid osteoma, which is characterized by nocturnal pain dramatically relieved by NSAIDs. The pain is mediated by high levels of prostaglandins, particularly PGE2, produced by robust COX-2 expression within the nidus. Osteoid osteomas are defined as being less than 1.5 to 2 cm in size (larger lesions are classified as osteoblastomas), have no malignant potential, are typically treated with radiofrequency ablation rather than wide resection, and display uniform, benign osteoblasts on histology.

Question 2769

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful mass in his left mid-thigh. Radiographs show a destructive diaphyseal lesion with an 'onion-skin' periosteal reaction. Biopsy reveals uniform small round blue cells. Which of the following genetic translocations is most characteristic of this lesion?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(9;22)(q22;q12)
. t(2;13)(q35;q14)

Correct Answer & Explanation

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

Explanation

Ewing sarcoma is a small round blue cell tumor typically found in the diaphysis of long bones in children and adolescents. It is characterized by the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma. t(12;16) is seen in myxoid liposarcoma. t(9;22) is seen in extraskeletal myxoid chondrosarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

Question 2770

Topic: 10. Pathology and Oncology

A 65-year-old man presents with a destructive, lytic lesion in the proximal humerus causing impending fracture. He has a history of a radical nephrectomy for renal cell carcinoma 5 years ago. A prophylactic stabilization is planned. Which of the following should be performed prior to the surgical stabilization?

. Radiation therapy to the whole bone
. Preoperative embolization of the lesion
. Neoadjuvant chemotherapy
. Core needle biopsy
. Intravenous bisphosphonates

Correct Answer & Explanation

. Preoperative embolization of the lesion

Explanation

Metastatic bone lesions from renal cell carcinoma (RCC) and thyroid carcinoma are characteristically hypervascular. Preoperative embolization is highly recommended within 24 to 48 hours prior to surgical intervention (such as curettage and stabilization or wide resection) to significantly reduce intraoperative blood loss.

Question 2771

Topic: 10. Pathology and Oncology

A 50-year-old man presents with a deep, painless, 8-cm soft tissue mass in his anterior thigh. MRI suggests a high-grade soft-tissue sarcoma. An incisional biopsy is planned. Which of the following is a fundamental principle of performing a biopsy for a suspected musculoskeletal sarcoma?

. The biopsy tract should be placed transversely across the extremity
. A tourniquet should be inflated and then deflated before closure to ensure hemostasis
. The biopsy incision should be placed in line with the planned definitive resection incision
. The deep fascia should be widely opened to adequately visualize the tumor margins
. Extensive soft-tissue dissection should be performed to free the tumor capsule

Correct Answer & Explanation

. The biopsy incision should be placed in line with the planned definitive resection incision

Explanation

Biopsy of a suspected sarcoma must be carefully planned. The incision should be longitudinal (in line with the extremity) so that the entire biopsy tract and scar can be excised en bloc with the tumor during definitive wide resection. Transverse incisions contaminate multiple compartments or wide areas. Hemostasis is critical to prevent hematoma (which spreads tumor cells), so if a tourniquet is used, it should be released prior to closure. Dissection must be minimal to avoid contaminating new planes.

Question 2772

Topic: Bone Tumors

A 19-year-old man presents with severe night pain in his right shin that is dramatically relieved by nonsteroidal anti-inflammatory drugs (NSAIDs). CT scan shows a 7-mm radiolucent nidus surrounded by dense reactive cortical sclerosis in the tibial diaphysis. If the patient elects for surgical intervention, what is the most appropriate definitive management?

. En bloc resection with wide margins
. Radiofrequency ablation (RFA)
. Radiation therapy
. Intralesional injection of corticosteroids
. Amputation

Correct Answer & Explanation

. Radiofrequency ablation (RFA)

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma (nidus < 1.5 cm, characteristic night pain relieved by NSAIDs). Radiofrequency ablation (RFA) is the current standard of care for definitive treatment of typical appendicular osteoid osteomas when non-operative management fails or the patient desires intervention. RFA is highly successful, less invasive, and avoids the structural weakening of the bone associated with open surgical excision.

Question 2773

Topic: 10. Pathology and Oncology
A 22-year-old man is diagnosed with an osteosarcoma of the distal femur. Biopsy reveals a high-grade tumor. MRI shows that the tumor has broken through the posterior cortex into the surrounding soft tissues, but whole-body staging reveals no lung or distant bone metastases. According to the Musculoskeletal Tumor Society (Enneking) staging system, what is the stage of this tumor?
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIB

Explanation

The Enneking (MSTS) staging system classifies malignant bone tumors based on Grade (I = low grade, II = high grade), Compartment (A = intracompartmental, B = extracompartmental), and Metastasis (M0 = none, M1 = metastasis). A high-grade tumor is Stage II. Cortical breakthrough extending into the soft tissue makes it extracompartmental (B). Therefore, it is Stage IIB. Any presence of metastasis would make it Stage III.

Question 2774

Topic: 10. Pathology and Oncology

A 68-year-old woman presents with persistent lower back pain. Radiographs reveal a purely lytic 'punched-out' lesion in the L3 vertebral body. Laboratory studies show hypercalcemia, anemia, and a monoclonal spike on serum protein electrophoresis. What is the most appropriate test to definitively confirm the diagnosis and staging of the underlying disease process?

. Open biopsy of the L3 vertebra
. Bone marrow aspirate and biopsy
. Whole-body technetium-99m bone scan
. CT-guided biopsy of the L3 vertebra
. Positron emission tomography (PET) scan

Correct Answer & Explanation

. Bone marrow aspirate and biopsy

Explanation

The clinical picture (lytic bone lesions, hypercalcemia, anemia, monoclonal gammopathy) is highly characteristic of multiple myeloma. The definitive test for diagnosing and staging multiple myeloma is a bone marrow aspirate and biopsy to quantify the percentage of clonal plasma cells (usually >10% required). A whole-body technetium bone scan is often falsely negative (cold) in myeloma because it relies on osteoblastic activity, which is suppressed in this disease.

Question 2775

Topic: Bone Tumors
A 9-year-old girl is evaluated for a severe varus deformity of her proximal femur, described radiographically as a 'shepherd's crook'. She is noted to have large, irregular areas of skin hyperpigmentation on her trunk. Which of the following endocrine abnormalities is most commonly associated with this patient's underlying condition?
. Precocious puberty
. Hypothyroidism
. Hyperparathyroidism
. Adrenal insufficiency
. Type 1 diabetes mellitus

Correct Answer & Explanation

. Precocious puberty

Explanation

The patient has McCune-Albright syndrome, which is defined by the classic triad of polyostotic fibrous dysplasia (causing the 'shepherd's crook' deformity), café-au-lait spots with irregular 'coast of Maine' borders, and autonomous endocrine hyperfunction. The most common endocrine manifestation is precocious puberty. It is caused by a somatic activating mutation in the GNAS gene.

Question 2776

Topic: 10. Pathology and Oncology

A 28-year-old man presents with a slow-growing, deep-seated, painful mass near his knee joint that has been present for over a year. MRI reveals a well-circumscribed soft-tissue mass with some internal calcifications adjacent to the joint, but not within it. Which of the following is true regarding this specific tumor type?

. It typically arises directly from the true intra-articular synovial lining
. It is characterized by the t(X;18)(p11;q11) chromosomal translocation
. It is universally resistant to radiotherapy and chemotherapy
. Lymph node metastases are extremely rare (<1%)
. Histologically, it is composed exclusively of uniform round blue cells

Correct Answer & Explanation

. It is characterized by the t(X;18)(p11;q11) chromosomal translocation

Explanation

The presentation describes a synovial sarcoma. Despite its name, it rarely arises from the actual intra-articular synovium; instead, it typically occurs in the soft tissues near large joints. The hallmark genetic mutation is the t(X;18)(p11;q11) translocation, creating the SYT-SSX fusion gene. Unlike many other soft tissue sarcomas, it has a relatively higher propensity for regional lymph node metastasis (up to 10-20%), and histologically it can be biphasic (containing both spindle and epithelial cells).

Question 2777

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive thigh pain and swelling, accompanied by low-grade fever. Radiographs show a permeative, diaphyseal lesion with an 'onion skin' periosteal reaction. A biopsy reveals sheets of uniform small, round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

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

Explanation

The clinical presentation and biopsy findings are characteristic of Ewing sarcoma. Approximately 85-90% of Ewing sarcomas exhibit the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion gene. t(X;18) is associated with synovial sarcoma; t(12;16) with myxoid liposarcoma; t(9;22) with chronic myelogenous leukemia (CML) and some acute lymphoblastic leukemias; and t(2;13) with alveolar rhabdomyosarcoma.

Question 2778

Topic: 10. Pathology and Oncology

A 60-year-old woman with a history of breast cancer presents with moderate functional pain in her left thigh. Radiographs reveal a purely lytic lesion in the proximal diaphysis of the left femur that involves 50% of the cortical diameter. According to Mirels' criteria, what is her score and the recommended orthopedic management?

. Score 8; radiation therapy alone
. Score 9; prophylactic internal fixation
. Score 10; radiation therapy alone
. Score 10; prophylactic internal fixation
. Score 11; prophylactic internal fixation

Correct Answer & Explanation

. Score 9; prophylactic internal fixation

Explanation

Mirels' criteria are used to predict the risk of pathologic fracture and guide prophylactic fixation. The four categories (scored 1 to 3) are Site (Upper limb=1, Lower limb=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Functional=3), Lesion Nature (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3 of cortex=1, 1/3 to 2/3 of cortex=2, >2/3 of cortex=3). For this patient: Site = Lower limb (2), Pain = Moderate (2), Lesion = Lytic (3), Size = 50% (2). Total score = 2 + 2 + 3 + 2 = 9. A score of 9 or greater carries a high risk of fracture, and prophylactic internal fixation is highly recommended.

Question 2779

Topic: 10. Pathology and Oncology

A 35-year-old man presents with a slow-growing, deep-seated, painful mass in the plantar aspect of his foot. MRI demonstrates a well-circumscribed soft-tissue mass adjacent to the plantar fascia. Biopsy reveals a biphasic tumor with both epithelial (glandular) and spindle cell components. What is the most likely cytogenetic abnormality associated with this diagnosis?

. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. MDM2 amplification
. t(11;22)(q24;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

The presentation of a deep, painful soft-tissue mass in the foot of a young adult, combined with biphasic histology, strongly indicates synovial sarcoma. This tumor is classically associated with the t(X;18)(p11;q11) translocation, which creates the SYT-SSX fusion protein. Despite its name, synovial sarcoma rarely arises from the actual synovium of a joint.

Question 2780

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with chronic left shoulder pain. Radiographs reveal a well-demarcated, eccentric, lytic lesion in the proximal humeral epiphysis with a thin sclerotic rim. Histological examination shows mononuclear cells with grooved nuclei ('coffee bean' appearance) and areas of pericellular 'chicken-wire' calcification. What is the most likely diagnosis?

. Giant cell tumor
. Clear cell chondrosarcoma
. Chondroblastoma
. Osteoblastoma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare benign cartilage-producing tumor that almost exclusively arises in the epiphysis or apophysis of long bones in skeletally immature patients. The histologic hallmarks are chondroblasts with grooved, indented nuclei (coffee bean shape) and fine network-like 'chicken-wire' calcifications. Although giant cell tumors also occur in the epiphysis, they typically manifest in skeletally mature patients (closed physes) and lack chicken-wire calcifications.

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