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10. Pathology and Oncology MCQs

Practice Set 193 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 3841

Topic: 10. Pathology and Oncology

A 65-year-old male with a known history of Ollier disease presents with a rapidly enlarging, painful mass in his left hand over the past 3 months.

Given the sudden clinical change, what is the most likely complication?

. Pathologic fracture
. Aneurysmal bone cyst formation
. Malignant transformation to secondary chondrosarcoma
. Malignant transformation to osteosarcoma
. Infection of the enchondroma

Correct Answer & Explanation

. Malignant transformation to secondary chondrosarcoma

Explanation

Patients with Ollier disease have a high risk (up to 25-30%) of malignant transformation of their enchondromas. Rapid growth or new pain in a previously stable lesion strongly suggests secondary chondrosarcoma.

Question 3842

Topic: 10. Pathology and Oncology

When evaluating a cartilaginous lesion of the medullary canal, which of the following histological findings strongly favors a diagnosis of low-grade chondrosarcoma over an enchondroma?

. Permeation and entrapment of host lamellar bone trabeculae by the tumor
. Presence of abundant calcified cartilage matrix
. Low cellularity with abundant hyaline matrix
. Lack of cytological atypia or mitotic figures
. Absence of myxoid changes

Correct Answer & Explanation

. Permeation and entrapment of host lamellar bone trabeculae by the tumor

Explanation

The permeation and entrapment of pre-existing host bone trabeculae by cartilaginous tissue is a hallmark of invasion, which strongly differentiates a low-grade chondrosarcoma from a benign enchondroma.

Question 3843

Topic: 10. Pathology and Oncology

A 35-year-old asymptomatic male incidentally discovers a 3 cm medullary lesion with stippled "rings and arcs" calcification in the proximal humerus.

What is the most appropriate next step in management?

. Wide surgical excision
. Core needle biopsy
. Observation with serial radiographs
. Extended curettage and bone grafting
. Neoadjuvant chemotherapy

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

This is a classic presentation of an asymptomatic enchondroma, characterized by central "rings and arcs" calcifications without cortical destruction. Observation with serial radiographs is the standard of care for asymptomatic incidental enchondromas in the appendicular skeleton.

Question 3844

Topic: Bone Tumors

A 28-year-old male presents with a painless palpable mass over the proximal humerus. Radiographs show a small surface lesion causing cortical saucerization with a well-defined sclerotic margin.

What is the most likely diagnosis?

. Periosteal chondrosarcoma
. Periosteal chondroma
. Osteochondroma
. Parosteal osteosarcoma
. Chondromyxoid fibroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas are benign surface lesions typically presenting with cortical saucerization and a thick sclerotic margin. Unlike periosteal chondrosarcomas, they are usually less than 3 cm in size and possess a well-defined, intact sclerotic rim.

Question 3845

Topic: 10. Pathology and Oncology

A 22-year-old female presents with a moderately painful, eccentric, radiolucent lesion in the metaphysis of the proximal tibia. Histology reveals a lobular architecture with hypercellular peripheries and hypocellular centers containing stellate cells in a myxoid background. What is the most appropriate treatment?

. Observation
. Radiofrequency ablation
. Intralesional curettage alone
. Extended curettage with local adjuvant
. Wide en bloc resection

Correct Answer & Explanation

. Extended curettage with local adjuvant

Explanation

The diagnosis is chondromyxoid fibroma (CMF), a benign but locally aggressive cartilage tumor. Treatment requires extended intralesional curettage with a high-speed burr and local adjuvants (like phenol or cryotherapy) to minimize the risk of local recurrence.

Question 3846

Topic: 10. Pathology and Oncology

A 48-year-old male with a known history of an osteochondroma on his distal femur notices recent enlargement and increasing pain. MRI demonstrates a cartilaginous cap thickness of 2.5 cm. What is the most likely diagnosis?

. Benign growth of osteochondroma
. Secondary chondrosarcoma
. Osteosarcoma
. Chondroblastoma
. Dedifferentiated chondrosarcoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

In skeletally mature adults, an enlarging osteochondroma with pain and a cartilage cap thicker than 2 cm is highly suspicious for malignant transformation into a secondary chondrosarcoma. Wide surgical resection is indicated.

Question 3847

Topic: Bone Tumors

A 12-year-old boy presents with right knee pain. Radiographs reveal an eccentric, lytic surface lesion causing cortical scalloping on the proximal medial tibia without medullary extension.

What is the most likely diagnosis?

. Osteochondroma
. Periosteal chondroma
. Non-ossifying fibroma
. Chondromyxoid fibroma
. Periosteal osteosarcoma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal (juxtacortical) chondromas typically present as eccentric, surface lesions causing a well-defined cortical scalloping with sclerotic margins. They usually measure less than 3 cm and do not invade the medullary canal.

Question 3848

Topic: 10. Pathology and Oncology

A 25-year-old male presents with chronic knee pain. Imaging reveals an epiphyseal lytic lesion in the distal femur. Histology demonstrates mononuclear cells with longitudinal nuclear grooves and areas of eosinophilic matrix with "chicken-wire" calcifications. What is the diagnosis?

. Giant cell tumor of bone
. Chondroblastoma
. Clear cell chondrosarcoma
. Aneurysmal bone cyst
. Enchondroma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastomas are benign, cartilage-producing tumors that characteristically occur in the epiphysis of long bones in young patients. Histology classically shows chondroblasts with grooved nuclei and "chicken-wire" pericellular calcifications.

Question 3849

Topic: 10. Pathology and Oncology

Which of the following radiographic features best distinguishes a low-grade intramedullary chondrosarcoma from a benign enchondroma in a long bone?

. Presence of stippled calcifications
. Endosteal scalloping greater than two-thirds of the cortical thickness
. Location in the metaphysis
. Size less than 2 cm
. Absence of periosteal reaction

Correct Answer & Explanation

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

Explanation

Endosteal scalloping that exceeds two-thirds of the cortical thickness, cortical breakthrough, and soft tissue mass are hallmark signs differentiating a low-grade chondrosarcoma from an enchondroma. Enchondromas typically cause minimal or no endosteal scalloping in long bones.

Question 3850

Topic: 10. Pathology and Oncology

A 22-year-old patient presents with a palpable mass on the posterior surface of the proximal humerus.

A biopsy confirms a periosteal chondroma. What is the recommended treatment for a symptomatic periosteal chondroma?

. Intralesional curettage alone
. Marginal or en bloc excision with the underlying cortex
. Radiation therapy
. Chemotherapy followed by wide resection
. Amputation

Correct Answer & Explanation

. Marginal or en bloc excision with the underlying cortex

Explanation

Symptomatic periosteal chondromas are best treated with marginal or en bloc excision, including the underlying sclerotic cortex, to minimize the risk of local recurrence. Intralesional curettage has a significantly higher recurrence rate.

Question 3851

Topic: Bone Tumors

A 16-year-old male is diagnosed with an osteoid osteoma of the proximal femur. Which of the following best describes the molecular etiology of his severe nocturnal pain?

. Overexpression of RANKL
. Production of interleukin-1 by osteoclasts
. High local production of Prostaglandin E2 (PGE2)
. Release of substance P from surrounding nerve roots
. Histamine release by mast cells in the nidus

Correct Answer & Explanation

. High local production of Prostaglandin E2 (PGE2)

Explanation

The severe nocturnal pain characteristic of osteoid osteoma is caused by high levels of prostaglandins, particularly PGE2, produced by the nidus. This is why the pain is classically and dramatically relieved by NSAIDs.

Question 3852

Topic: 10. Pathology and Oncology

A 14-year-old girl complains of increasing right thigh pain. Radiographs demonstrate a diaphyseal permeative lytic lesion with an "onion skin" periosteal reaction. A biopsy is planned. Which cytogenetic abnormality is most likely to be found?

. t(X;18)(p11;q11)
. t(11;22)(q24;q12)
. 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 patient's presentation is classic for Ewing sarcoma. Ewing sarcoma is primarily driven by a balanced translocation between chromosomes 11 and 22, t(11;22)(q24;q12), which results in the EWS-FLI1 fusion protein.

Question 3853

Topic: 10. Pathology and Oncology

A patient with suspected Maffucci syndrome presents with a rapidly growing hand mass.

Besides a high risk for malignant transformation to chondrosarcoma, patients with Maffucci syndrome are at a significantly increased risk for which of the following?

. Osteosarcoma
. Visceral and central nervous system malignancies
. Leukemia
. Pulmonary fibrosis
. Aortic aneurysm

Correct Answer & Explanation

. Visceral and central nervous system malignancies

Explanation

Maffucci syndrome (multiple enchondromas and soft tissue hemangiomas) carries a very high risk of malignant transformation. This includes not only chondrosarcoma but also visceral, brain (e.g., astrocytomas), and ovarian malignancies.

Question 3854

Topic: 10. Pathology and Oncology

A 30-year-old woman presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion extending to the subchondral bone in the proximal tibia. A biopsy demonstrates multinucleated giant cells in a background of uniform mononuclear cells. What is the molecular target of the pharmacological agent used for unresectable cases of this tumor?

. RANKL
. VEGF
. mTOR
. Tyrosine kinase
. TNF-alpha

Correct Answer & Explanation

. RANKL

Explanation

The diagnosis is a Giant Cell Tumor (GCT) of bone. Denosumab, a monoclonal antibody that targets RANK Ligand (RANKL), is used for unresectable or metastatic GCTs to inhibit the formation and function of osteoclast-like giant cells.

Question 3855

Topic: 10. Pathology and Oncology

A 30-year-old female presents with a closed, minimally displaced pathologic fracture of the proximal phalanx of the index finger. Radiographs show an expansile, centrally located lytic lesion with stippled calcifications.

What is the most appropriate initial management?

. Immediate intralesional curettage and bone grafting
. Ray amputation
. Immobilization until fracture healing, followed by curettage and grafting
. Wide local excision and strut allografting
. Core needle biopsy and referral for radiotherapy

Correct Answer & Explanation

. Immobilization until fracture healing, followed by curettage and grafting

Explanation

Enchondromas are the most common primary bone tumor of the hand. When presenting with a pathologic fracture, the initial treatment is immobilization to allow fracture healing, followed by elective curettage and bone grafting.

Question 3856

Topic: Bone Tumors
A 15-year-old boy presents with a painless mass over the proximal humerus. Radiographs show a small (< 3 cm), cortically based lucent lesion with a sclerotic margin and cortical saucerization. What is the most likely diagnosis?
. Osteoid osteoma
. Periosteal chondrosarcoma
. Periosteal chondroma
. Non-ossifying fibroma
. Osteochondroma

Correct Answer & Explanation

. Periosteal chondroma

Explanation

Periosteal chondromas typically present in the second decade as small (< 3 cm) surface lesions with cortical saucerization and a sclerotic inner margin. Periosteal chondrosarcomas have a similar appearance but are generally larger (> 3 cm) and occur in older adults.

Question 3857

Topic: 10. Pathology and Oncology
A 45-year-old man with a known asymptomatic distal femur enchondroma presents with new-onset, progressive night pain over the past 3 months. Imaging shows increased radiolucency and endosteal scalloping > 2/3 of the cortical thickness. Biopsy confirms secondary chondrosarcoma. What is the most appropriate definitive treatment?
. Neoadjuvant chemotherapy followed by wide resection
. Intralesional curettage with phenol and cement
. Wide surgical resection
. Primary radiation therapy
. Amputation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Chondrosarcomas are generally insensitive to chemotherapy and radiation. The standard treatment for conventional chondrosarcoma (grade 2 or higher) is wide surgical resection to achieve negative margins.

Question 3858

Topic: 10. Pathology and Oncology

A 32-year-old woman is diagnosed with an atypical cartilaginous tumor (Grade 1 chondrosarcoma) of the proximal humerus. What is the currently recommended surgical management?

. Observation with serial radiographs
. Extended intralesional curettage with local adjuvant treatment
. Wide en bloc resection and endoprosthetic reconstruction
. Radiation therapy
. Neoadjuvant chemotherapy followed by resection

Correct Answer & Explanation

. Extended intralesional curettage with local adjuvant treatment

Explanation

Atypical cartilaginous tumors (Grade 1 chondrosarcomas) in the appendicular skeleton are increasingly treated with extended intralesional curettage and local adjuvants (e.g., high-speed burr, cryotherapy, or phenol). This provides excellent local control while preserving bone stock and joint function.

Question 3859

Topic: Bone Tumors

A 22-year-old female presents with multiple hard bony protuberances and bluish soft-tissue nodules on her hands. Radiographs reveal multiple enchondromas. What is her lifetime risk of developing any malignancy?

. Less than 5%
. 10-15%
. 25-30%
. 50-60%
. Nearly 100%

Correct Answer & Explanation

. Nearly 100%

Explanation

This patient has Maffucci syndrome, characterized by multiple enchondromas and soft-tissue hemangiomas. Patients with Maffucci syndrome have a lifetime risk of developing ANY malignancy (including chondrosarcoma and visceral/brain malignancies) approaching 100%, which is higher than the risk in Ollier disease.

Question 3860

Topic: 10. Pathology and Oncology
A 60-year-old male presents with deep thigh pain. Imaging reveals a large distal femoral metaphyseal lesion. Biopsy demonstrates well-differentiated hyaline cartilage sharply demarcated from a high-grade pleomorphic spindle cell sarcoma. What is the diagnosis?
. Mesenchymal chondrosarcoma
. Clear cell chondrosarcoma
. Conventional Grade III chondrosarcoma
. Dedifferentiated chondrosarcoma
. Osteosarcoma with chondroblastic features

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

Dedifferentiated chondrosarcoma is characterized by a bimorphic histologic appearance, where a low-grade chondrosarcoma lies adjacent to a high-grade non-cartilaginous sarcoma. This abrupt histological transition is a hallmark of the disease.

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