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10. Pathology and Oncology MCQs

Practice Set 295 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 5881

Topic: Bone Tumors

A 13-year-old girl presents with right groin pain and the imaging and histology shown. The histology reveals irregular, woven bone trabeculae in a fibrous stroma without osteoblastic rimming ('Chinese letter' pattern). This condition is associated with a somatic activating mutation in which of the following genes?

. EXT1
. GNAS1
. RB1
. TP53
. FGFR3

Correct Answer & Explanation

. GNAS1

Explanation

Correct Answer: BThe clinical, radiographic (ground-glass appearance, Shepherd's crook deformity), and histologic ('Chinese letter' woven bone lacking osteoblastic rimming in a fibrous stroma) findings are diagnostic of fibrous dysplasia. Fibrous dysplasia is caused by a somatic, post-zygotic activating mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein (Gs-alpha), leading to increased intracellular cAMP and abnormal osteoblast differentiation.

Question 5882

Topic: Bone Tumors

A 13-year-old girl presents with right groin pain. Radiographs reveal a ground-glass lesion in the proximal femur with a mild 'Shepherd's crook' deformity. Histologic examination demonstrates proliferating fibroblasts in a loose spindle cell background with dysplastic metaplastic trabeculae arranged in a 'Chinese letter' pattern. Which of the following is the most likely diagnosis?

. Unicameral bone cyst
. Aneurysmal bone cyst
. Fibrous dysplasia
. Chondromyxoid fibroma
. Osteofibrous dysplasia

Correct Answer & Explanation

. Fibrous dysplasia

Explanation

Correct Answer: Fibrous dysplasiaThe clinical, radiographic, and histologic findings are classic for fibrous dysplasia. Radiographically, it presents as a lytic, expansile lesion with a 'ground-glass' matrix, often leading to bowing deformities in the proximal femur known as a 'Shepherd's crook' deformity. Histologically, it is characterized by a fibrous stroma containing irregular, woven bone trabeculae that lack osteoblastic rimming, often described as having a 'Chinese letter' or 'alphabet soup' appearance.

Question 5883

Topic: Bone Tumors

A 14-year-old girl presents with a painful mass in her proximal humerus. Imaging is provided, demonstrating an expansile, eccentric, lytic lesion with fluid-fluid levels on MRI. Following curettage and bone grafting, which of the following factors is most strongly associated with an increased risk of local recurrence?

. Patient age greater than 20 years
. Closed physes
. Young age and open physes
. Use of a high-speed burr during curettage
. Use of phenol as a local adjuvant

Correct Answer & Explanation

. Young age and open physes

Explanation

Correct Answer: Young age and open physesThe imaging is classic for an aneurysmal bone cyst (ABC), showing fluid-fluid levels on MRI. Factors associated with a higher rate of local recurrence include young age, open physes, and inadequate surgical margins. The use of a high-speed burr and local adjuvants (like phenol or argon beam) decreases the recurrence rate.

Question 5884

Topic: 10. Pathology and Oncology

A 65-year-old woman presents with chronic aching in her elbow. Radiographs and a biopsy specimen are shown. The histology reveals round to oval cells with an eccentric nucleus, prominent nucleolus, and a clear perinuclear area representing the Golgi apparatus. Which of the following is the most likely diagnosis?

. Metastatic thyroid carcinoma
. Lymphoma
. Multiple myeloma
. Ewing sarcoma
. Osteomyelitis

Correct Answer & Explanation

. Multiple myeloma

Explanation

Correct Answer: CThe histologic description and image are pathognomonic for plasma cells, which characterize multiple myeloma. The cells are round/oval with an eccentric nucleus, prominent nucleolus, and a perinuclear clearing (halo) that represents the prominent Golgi apparatus. Multiple myeloma frequently presents as lytic bone lesions in older adults.

Question 5885

Topic: 10. Pathology and Oncology

A 14-year-old boy with a biopsy-proven conventional osteosarcoma of the distal femur completes his course of neoadjuvant chemotherapy and undergoes surgical resection. Pathological analysis of the resected specimen is performed. Which of the following findings is the most reliable predictor of long-term overall survival?

. Complete surgical margins of 2 cm or greater
. Greater than 90% tumor necrosis
. Absence of lung micrometastases on pre-op CT
. Intact periosteal reaction
. Low mitotic index

Correct Answer & Explanation

. Greater than 90% tumor necrosis

Explanation

The histological response to neoadjuvant chemotherapy, defined by the percentage of tumor necrosis, is the most important prognostic factor in conventional osteosarcoma. Greater than 90% necrosis indicates a good response and correlates with significantly higher survival rates.

Question 5886

Topic: 10. Pathology and Oncology

A 15-year-old girl has a distal femoral biopsy confirming a high-grade conventional osteosarcoma. Mutations in which two tumor suppressor genes are most profoundly linked to the genetic pathogenesis of this specific malignancy?

. TP53 and RB1
. BRCA1 and BRCA2
. APC and MLH1
. EXT1 and EXT2
. NF1 and NF2

Correct Answer & Explanation

. TP53 and RB1

Explanation

Conventional osteosarcoma is strongly associated with mutations in the TP53 (associated with Li-Fraumeni syndrome) and RB1 (associated with Hereditary Retinoblastoma) tumor suppressor genes.

Question 5887

Topic: 10. Pathology and Oncology

A 45-year-old male presents with persistent thigh pain. Radiographs show a permeative, destructive diaphyseal lesion with minimal periosteal reaction. Biopsy reveals sheets of uniform round blue cells. Immunohistochemistry is strongly positive for CD20 and CD45. What is the most appropriate initial management?

. Neoadjuvant chemotherapy and wide resection
. Wide surgical resection alone
. Intralesional curettage and bone grafting
. Chemotherapy and radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Chemotherapy and radiation therapy

Explanation

Primary bone lymphoma (diffuse large B-cell) typically presents as a permeative lesion in adults. It is highly chemo- and radiosensitive, making systemic chemotherapy combined with radiation the primary treatment. Surgery is generally reserved for impending or actual fractures.

Question 5888

Topic: 10. Pathology and Oncology
A 50-year-old male with Ollier disease presents with new-onset, progressive pain in his proximal humerus over the last 3 months. Radiographs demonstrate a pre-existing cartilaginous lesion now showing endosteal scalloping > 2/3 of cortical thickness and a new soft tissue mass. What is the most likely diagnosis?
. Chondroblastoma
. Aneurysmal bone cyst
. Secondary chondrosarcoma
. Osteosarcoma
. Metastatic carcinoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Patients with Ollier disease have a high risk (up to 30%) of malignant transformation into secondary chondrosarcoma. Pain, deep endosteal scalloping, cortical destruction, and soft tissue extension are classic signs of this malignant degeneration.

Question 5889

Topic: 10. Pathology and Oncology

A 45-year-old female is diagnosed with multiple enchondromas predominantly affecting her right arm and leg, as well as multiple soft-tissue hemangiomas.

Which of the following statements is true regarding her condition?

. It is inherited in an autosomal dominant pattern
. It carries a 1% risk of malignant transformation to chondrosarcoma
. It is known as Ollier disease
. It carries a near 100% lifetime risk of malignant transformation to chondrosarcoma or visceral malignancies
. The primary gene mutation involves COL2A1

Correct Answer & Explanation

. It carries a near 100% lifetime risk of malignant transformation to chondrosarcoma or visceral malignancies

Explanation

Maffucci syndrome presents with multiple enchondromatosis and soft-tissue hemangiomas. It is associated with a nearly 100% lifetime risk of malignant transformation, including chondrosarcoma and visceral or brain malignancies.

Question 5890

Topic: 10. Pathology and Oncology

A 65-year-old man presents with thigh pain. Radiographs reveal a permeative, moth-eaten diaphyseal lesion in the femur with minimal periosteal reaction. Biopsy shows small, round blue cells that stain positive for CD45 and CD20. What is the most appropriate primary treatment for an uncomplicated presentation of this disease?

. Wide surgical resection followed by chemotherapy
. Neoadjuvant chemotherapy, wide resection, and maintenance chemotherapy
. Systemic chemotherapy combined with local radiation therapy
. Above-knee amputation
. Intralesional curettage and bone grafting

Correct Answer & Explanation

. Systemic chemotherapy combined with local radiation therapy

Explanation

The diagnosis is primary bone lymphoma (typically diffuse large B-cell). The standard of care is systemic multi-agent chemotherapy (such as CHOP-R) combined with local radiation therapy; surgery is reserved strictly for impending or actual pathologic fractures.

Question 5891

Topic: 10. Pathology and Oncology

A 15-year-old girl presents with multiple asymmetric cartilaginous lesions in the appendicular skeleton and bluish, compressible subcutaneous nodules on her extremities. Which of the following is true regarding her condition?

. It is inherited in a strict autosomal dominant pattern.
. The risk of malignant transformation to chondrosarcoma or other malignancies approaches 100%.
. The subcutaneous nodules are histologically proven neurofibromas.
. The condition is primarily caused by an inherited EXT1 or EXT2 gene mutation.
. The risk of malignant transformation is roughly 25% by age 40.

Correct Answer & Explanation

. The risk of malignant transformation to chondrosarcoma or other malignancies approaches 100%.

Explanation

The patient has Maffucci syndrome, distinguished from Ollier disease by the presence of soft tissue hemangiomas. Unlike Ollier disease (which carries a 25-30% malignancy risk), the risk of malignant transformation in Maffucci syndrome approaches 100% over the patient's lifetime.

Question 5892

Topic: 10. Pathology and Oncology

A 32-year-old female presents with progressive knee pain. Radiographs demonstrate an eccentric, lytic, epiphyseal-metaphyseal lesion of the distal femur extending to the subchondral bone.

Biopsy confirms a Giant Cell Tumor of bone. Which cell type is considered the primary neoplastic cell in this lesion?

. Multinucleated giant cell
. Mononuclear spindle cell
. Chondroblast
. Osteoblast
. Histiocyte

Correct Answer & Explanation

. Mononuclear spindle cell

Explanation

The neoplastic cells in a Giant Cell Tumor of bone are the mononuclear stromal (spindle) cells, which express RANKL. The characteristic multinucleated giant cells are merely reactive osteoclast-like cells recruited by the stromal cells.

Question 5893

Topic: 10. Pathology and Oncology

A 65-year-old male presents with severe, unremitting thigh pain. Radiographs demonstrate a permeative, moth-eaten diaphyseal lesion in the femur with minimal periosteal reaction.

Biopsy reveals sheets of small round blue cells that stain positive for CD20. What is the most likely diagnosis?

. Ewing sarcoma
. Multiple myeloma
. Primary lymphoma of bone
. Osteosarcoma
. Metastatic prostate cancer

Correct Answer & Explanation

. Primary lymphoma of bone

Explanation

Primary bone lymphoma typically presents in older adults with a destructive, permeative lesion and remarkably minimal periosteal reaction. Positivity for CD20 confirms a B-cell lineage, distinguishing it from Ewing sarcoma and myeloma.

Question 5894

Topic: 10. Pathology and Oncology

A 45-year-old asymptomatic male is found to have an incidental well-defined medullary lesion in the proximal humerus with stippled "arcs and rings" calcifications.

Which MRI finding most strongly suggests transformation to a low-grade chondrosarcoma rather than a benign enchondroma?

. Endosteal scalloping greater than two-thirds of the cortical thickness
. Lobular high signal on T2-weighted images
. Intralesional calcification on gradient echo
. Lesion size less than 3 cm
. Perilesional bone marrow edema

Correct Answer & Explanation

. Endosteal scalloping greater than two-thirds of the cortical thickness

Explanation

Features distinguishing low-grade chondrosarcoma from enchondroma include deep endosteal scalloping (greater than 2/3 of cortical thickness), cortical breakthrough, and soft tissue extension. Bone marrow edema can occasionally be seen in benign enchondromas, making deep scalloping a more reliable indicator.

Question 5895

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with multiple unilateral enchondromas causing limb-length discrepancy and angular deformity.

Physical examination reveals no cutaneous or soft tissue hemangiomas. What is the diagnosis, and what is the estimated lifetime risk of malignant transformation?

. Maffucci syndrome, 100% risk
. Ollier disease, 25-30% risk
. Multiple hereditary exostoses, 5% risk
. Fibrous dysplasia, 1% risk
. Ollier disease, 100% risk

Correct Answer & Explanation

. Ollier disease, 25-30% risk

Explanation

Ollier disease is characterized by multiple enchondromas, often with a unilateral predominance, without soft tissue hemangiomas (which would define Maffucci syndrome). The risk of malignant transformation to secondary chondrosarcoma in Ollier disease is roughly 25-30%.

Question 5896

Topic: 10. Pathology and Oncology

A 28-year-old patient undergoes extended intralesional curettage for a Campanacci Grade II giant cell tumor of the proximal tibia.

Which of the following surgical adjuncts is most commonly utilized to decrease the rate of local recurrence?

. High-speed burring and chemical/thermal cautery (e.g., phenol or argon beam)
. Preoperative radiation therapy
. Postoperative systemic chemotherapy
. Placement of a vascularized fibular graft
. Intralesional injection of absolute alcohol

Correct Answer & Explanation

. High-speed burring and chemical/thermal cautery (e.g., phenol or argon beam)

Explanation

The standard surgical treatment for most GCTs is extended intralesional curettage using a high-speed burr to remove macroscopic tumor. This is typically followed by local adjuvants like phenol, liquid nitrogen, or argon beam coagulation to eradicate residual microscopic disease.

Question 5897

Topic: 10. Pathology and Oncology

A 35-year-old male with a history of a distal radius giant cell tumor presents 2 years post-resection. Routine chest imaging reveals multiple small pulmonary nodules. Biopsy of a nodule confirms benign GCT histology. What is this phenomenon called, and what is its typical clinical behavior?

. Malignant transformation, rapidly fatal course
. Benign pulmonary metastasis, usually indolent course
. Radiation-induced sarcoma, requires immediate pneumonectomy
. Metastatic osteosarcoma, requires high-dose methotrexate
. Hamartoma formation, self-resolving within weeks

Correct Answer & Explanation

. Benign pulmonary metastasis, usually indolent course

Explanation

Giant Cell Tumors of bone can undergo "benign pulmonary metastasis" in 2-4% of cases. Despite the metastatic spread to the lungs, the lesions retain benign histology and often have an indolent clinical course, and can be managed with observation or surgical resection.

Question 5898

Topic: 10. Pathology and Oncology

A 55-year-old male presents with deep knee pain. Radiographs reveal a permeative diaphyseal lesion in the distal femur. Biopsy confirms primary non-Hodgkin lymphoma of bone. Which of the following is true regarding this condition?

. Surgical resection is the mainstay of treatment
. It classically presents with a prominent periosteal sunburst reaction
. The most common histological subtype is Hodgkin lymphoma
. It typically has a better prognosis than osteosarcoma of the extremity
. It usually lacks soft tissue extension on MRI

Correct Answer & Explanation

. It typically has a better prognosis than osteosarcoma of the extremity

Explanation

Primary lymphoma of bone typically has a better 5-year survival rate compared to conventional osteosarcoma. Treatment primarily consists of systemic chemotherapy and radiation, not surgical resection.

Question 5899

Topic: 10. Pathology and Oncology

A 35-year-old male undergoes curettage and cementing for a giant cell tumor (GCT) of the proximal tibia. Two years later, a chest CT reveals multiple small, asymptomatic pulmonary nodules. Biopsy of a nodule confirms metastatic GCT. What is the most appropriate next step in management?

. Immediate bilateral lung transplantation
. Observation or Denosumab therapy
. High-dose systemic chemotherapy with doxorubicin
. Radiation therapy to the lungs
. Radiofrequency ablation of all nodules

Correct Answer & Explanation

. Observation or Denosumab therapy

Explanation

Pulmonary metastases in GCT of bone are considered 'benign' implants and often have an indolent course. Management typically consists of observation, surgical resection if symptomatic and accessible, or targeted medical therapy like denosumab.

Question 5900

Topic: 10. Pathology and Oncology

A 25-year-old male presents with multiple asymmetric enchondromas predominantly involving the right side of his body, without any associated soft tissue vascular lesions. What is his estimated lifetime risk of malignant transformation to chondrosarcoma?

. Less than 1%
. 5-10%
. 25-30%
. 60-70%
. 100%

Correct Answer & Explanation

. 25-30%

Explanation

The patient has Ollier disease (multiple enchondromatosis without hemangiomas). The lifetime risk of malignant transformation to chondrosarcoma in Ollier disease is approximately 25-30%.

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