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10. Pathology and Oncology MCQs

Practice Set 347 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 6921

Topic: 10. Pathology and Oncology

A 75-year-old man with polyostotic Paget's disease presents with new-onset, unrelenting severe pain in his left thigh. Radiographs show a destructive, permeative lytic lesion disrupting the thickened cortex. What is the most likely diagnosis?

. Chondrosarcoma
. Ewing sarcoma
. Secondary osteosarcoma
. Multiple myeloma
. Metastatic prostate carcinoma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Malignant transformation occurs in about 1% of patients with Paget's disease, most commonly resulting in secondary osteosarcoma. It should be suspected in patients presenting with a sudden increase in localized, severe pain or a new mass.

Question 6922

Topic: Bone Tumors

A patient presents with sparse hair, a pear-shaped nose, and cone-shaped epiphyses of the hands. Additionally, the patient has multiple osteochondromas throughout the appendicular skeleton. Which contiguous gene deletion syndrome is this?

. TRPS Type 1
. TRPS Type 2 (Langer-Giedion syndrome)
. TRPS Type 3
. Trevor disease
. Ollier disease

Correct Answer & Explanation

. TRPS Type 2 (Langer-Giedion syndrome)

Explanation

TRPS Type 2 (Langer-Giedion syndrome) is a contiguous gene deletion syndrome affecting both TRPS1 (causing TRPS features) and EXT1 (causing multiple hereditary exostoses).

Question 6923

Topic: 10. Pathology and Oncology

A 70-year-old male with long-standing Paget's disease presents with new-onset, severe, unrelenting pain in his right femur. Radiographs reveal a new destructive lytic lesion with cortical breakthrough. What is the most likely diagnosis?

. Chondrosarcoma
. Osteosarcoma
. Ewing sarcoma
. Multiple myeloma
. Metastatic carcinoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma is the most common malignant transformation in Paget's disease, typically presenting with new severe pain and a destructive lesion in previously affected bone.

Question 6924

Topic: Bone Tumors
A rare subtype of autosomal recessive osteopetrosis is caused by a deficiency in carbonic anhydrase II (CA II). This specific genetic mutation is characteristically associated with which of the following triads?
. Osteopetrosis, renal tubular acidosis, and cerebral calcification
. Osteopetrosis, sensorineural deafness, and blue sclerae
. Osteopetrosis, multiple osteochondromas, and mental retardation
. Osteopetrosis, primary hyperparathyroidism, and pituitary adenoma
. Osteopetrosis, precocious puberty, and café-au-lait spots

Correct Answer & Explanation

. Osteopetrosis, renal tubular acidosis, and cerebral calcification

Explanation

Carbonic anhydrase II (CA II) deficiency causes a unique syndrome characterized by the triad of osteopetrosis, renal tubular acidosis, and cerebral calcifications (Guibaud-Vainsel syndrome).

Question 6925

Topic: 10. Pathology and Oncology

A 72-year-old man with a long-standing history of Paget's disease of the pelvis presents with new, severely worsening, and unrelenting localized pain. Radiographs demonstrate a new area of lytic destruction with cortical breakthrough and soft tissue extension. What is the most likely diagnosis?

. Chondrosarcoma
. Osteosarcoma
. Ewing sarcoma
. Multiple myeloma
. Giant cell tumor of bone

Correct Answer & Explanation

. Osteosarcoma

Explanation

Secondary osteosarcoma is the most common and feared malignant transformation in Paget's disease, occurring in approximately 1% of patients. It typically presents with sudden, severe pain and a destructive lytic lesion in a previously pagetic bone.

Question 6926

Topic: 10. Pathology and Oncology

Which of the following is an absolute indication for initiating medical treatment with nitrogen-containing bisphosphonates in a patient with Paget's disease of bone?

. Asymptomatic patient with slightly elevated alkaline phosphatase
. Preparation for elective orthopedic surgery on an actively pagetic bone
. Monostotic involvement of the clavicle without pain
. Sclerotic phase cortical thickening of the humerus in a sedentary patient
. Prevention of malignant transformation to osteosarcoma

Correct Answer & Explanation

. Preparation for elective orthopedic surgery on an actively pagetic bone

Explanation

Medical therapy is indicated to decrease hypervascularity and minimize intraoperative blood loss prior to elective surgery (e.g., total joint arthroplasty or osteotomy) on an actively pagetic bone. It does not prevent malignant transformation.

Question 6927

Topic: Bone Tumors

Trichorhinophalangeal Syndrome (TRPS) Type 2, also known as Langer-Giedion syndrome, is a contiguous gene deletion syndrome involving chromosome 8q23.3-q24.1. Which of the following phenotypic features reliably differentiates TRPS Type 2 from TRPS Type 1?

. Intellectual disability and multiple osteochondromas
. Deafness and blue sclerae
. Craniosynostosis and severe syndactyly
. Osteomyelitis of the jaw and cranial nerve palsies
. Hypercalcemia and recurrent renal stones

Correct Answer & Explanation

. Intellectual disability and multiple osteochondromas

Explanation

TRPS Type 2 is caused by the deletion of both the TRPS1 gene (causing TRPS features) and the adjacent EXT1 gene (causing multiple osteochondromas). It is also frequently accompanied by intellectual disability, unlike TRPS Type 1.

Question 6928

Topic: Bone Tumors

A 12-year-old girl is evaluated for short stature and joint deformities. Hand radiographs are obtained.

The image shows classic cone-shaped epiphyses. Which of the following physical examination findings is most consistently associated with this syndrome?

. Blue sclerae and dentinogenesis imperfecta
. Pear-shaped bulbous nose and sparse, thin hair
. Multiple cafe-au-lait spots and axillary freckling
. Precocious puberty and polyostotic fibrous dysplasia
. Enamel hypoplasia and delayed tooth eruption

Correct Answer & Explanation

. Pear-shaped bulbous nose and sparse, thin hair

Explanation

Cone-shaped epiphyses in the phalanges are a hallmark of Trichorhinophalangeal Syndrome (TRPS) Type 1. Clinically, patients present with a distinct facial phenotype including a bulbous (pear-shaped) nose, elongated philtrum, and sparse, fine hair.

Question 6929

Topic: 10. Pathology and Oncology

A 40-year-old patient with known adult-onset autosomal dominant osteopetrosis requires a dental extraction for a severely decayed molar. Which of the following is the most significant potential complication of this procedure in this patient?

. Giant cell tumor of the mandible
. Recurrent temporomandibular joint dislocation
. Osteomyelitis of the mandible
. Malignant transformation to ameloblastoma
. Bisphosphonate-related osteonecrosis of the jaw

Correct Answer & Explanation

. Osteomyelitis of the mandible

Explanation

Patients with osteopetrosis have poor medullary blood supply due to sclerotic bone obliterating the marrow cavity. Consequently, dental procedures pose a high risk for developing intractable osteomyelitis of the mandible or maxilla.

Question 6930

Topic: 10. Pathology and Oncology

A 72-year-old male with a long-standing history of Paget's disease presents with new, rapidly worsening, and unremitting pain in his right thigh. Radiographs demonstrate an aggressive, mixed lytic and sclerotic lesion with cortical destruction in the femoral diaphysis. What is the most likely diagnosis?

. Osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Metastatic carcinoma
. Multiple myeloma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Secondary osteosarcoma is the most common and deadliest primary bone malignancy that arises in the background of Paget's disease, affecting approximately 1% of patients. It typically presents with new, severe pain and aggressive cortical destruction, carrying a much poorer prognosis than primary osteosarcoma.

Question 6931

Topic: Bone Tumors

A 14-year-old girl presents with a 'Shepherd's crook' deformity of the proximal femur and a 'ground-glass' appearance on radiographs. Genetic testing reveals a somatic mutation in the GNAS gene. Which of the following is the most likely diagnosis?

. Osteogenesis Imperfecta
. Fibrous Dysplasia
. Osteopetrosis
. Multiple Hereditary Exostoses
. Paget's Disease

Correct Answer & Explanation

. Fibrous Dysplasia

Explanation

Correct Answer: BFibrous dysplasia is caused by a somatic mutation in the GNAS gene, leading to the replacement of normal bone with fibrous tissue and immature trabecular bone (ground-glass appearance). The 'Shepherd's crook' deformity is a classic varus deformity of the proximal femur seen in polyostotic fibrous dysplasia.

Question 6932

Topic: 10. Pathology and Oncology

In patients with Multiple Hereditary Exostoses (MHE), what is the estimated lifetime risk of malignant transformation of an osteochondroma into a secondary chondrosarcoma?

. Less than 1%
. 1% to 5%
. 10% to 15%
. 25% to 30%
. Over 50%

Correct Answer & Explanation

. 1% to 5%

Explanation

Correct Answer: BWhile solitary osteochondromas have a less than 1% risk of malignant transformation, patients with Multiple Hereditary Exostoses (MHE) have a higher risk, generally cited between 1% and 5%. A sudden increase in size or the onset of pain in a previously stable lesion after skeletal maturity should raise suspicion.

Question 6933

Topic: 10. Pathology and Oncology

Which of the following conditions is characterized by the association of multiple enchondromas and soft tissue hemangiomas?

. Ollier Disease
. McCune-Albright Syndrome
. Maffucci Syndrome
. Proteus Syndrome
. Jaffe-Campanacci Syndrome

Correct Answer & Explanation

. Maffucci Syndrome

Explanation

Correct Answer: CMaffucci Syndrome is characterized by multiple enchondromas and soft tissue cavernous hemangiomas (often containing phleboliths). It carries a significantly higher risk of malignant transformation (chondrosarcoma and visceral malignancies) compared to Ollier disease (which features enchondromas without hemangiomas).

Question 6934

Topic: Bone Tumors

A 10-year-old girl presents with precocious puberty, large 'cafe-au-lait' spots with irregular 'coast of Maine' borders, and polyostotic fibrous dysplasia. What is the underlying pathophysiology?

. Deficiency of Type 1 Collagen
. Constitutively active Gs-alpha protein signaling
. Inactivation of the EXT2 tumor suppressor gene
. Overexpression of Fibroblast Growth Factor 23 (FGF23)
. Mutation in the Cathepsin K gene

Correct Answer & Explanation

. Constitutively active Gs-alpha protein signaling

Explanation

Correct Answer: BThe triad of polyostotic fibrous dysplasia, cafe-au-lait spots, and hyperfunctioning endocrinopathies (like precocious puberty) defines McCune-Albright Syndrome. It is caused by a post-zygotic somatic mutation in the GNAS1 gene, which leads to constitutive activation of the Gs-alpha protein, stimulating adenylate cyclase and increasing intracellular cAMP.

Question 6935

Topic: 10. Pathology and Oncology

A neonate is born with a posteromedial bow of the left tibia and a severe calcaneovalgus positioning of the left foot. The parents are highly anxious about the child's future mobility. What represents the natural history of this specific condition?

. Progression to pseudarthrosis requiring early amputation
. Spontaneous resolution of the bowing with an ultimate residual limb-length discrepancy
. Development of progressive equinovarus contractures
. Early closure of the distal tibial physis leading to a varus ankle
. Malignant transformation to osteosarcoma in early adulthood

Correct Answer & Explanation

. Spontaneous resolution of the bowing with an ultimate residual limb-length discrepancy

Explanation

Unlike anterolateral bowing, posteromedial bowing of the tibia does not progress to pseudarthrosis and the angular deformity typically resolves spontaneously with growth. However, the affected limb will reliably demonstrate a limb-length discrepancy (usually 3-4 cm) at skeletal maturity.

Question 6936

Topic: Bone Tumors

A 5-year-old boy presents with a hard, painless swelling on the medial aspect of his right ankle and a progressive varus deformity. Radiographs show an irregular, multicentric radiopaque mass arising as an asymmetric overgrowth from the medial epiphysis of the distal tibia. What is the most likely diagnosis?

. Multiple hereditary exostoses
. Dysplasia epiphysealis hemimelica
. Chondroblastoma
. Ollier disease
. Osteopathia striata

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is a rare developmental disorder characterized by an osteochondroma-like asymmetric overgrowth of the epiphysis. It most commonly affects the medial side of the ankle or knee in young boys.

Question 6937

Topic: Bone Tumors

A 4-year-old boy presents with painless, localized swelling on the medial aspect of his ankle. Radiographs reveal an asymmetric, irregular ossification mass arising from the medial half of the distal tibial epiphysis. What is the most likely diagnosis?

. Chondroblastoma
. Dysplasia epiphysealis hemimelica
. Osteochondroma
. Osteopathia striata
. Melorheostosis

Correct Answer & Explanation

. Dysplasia epiphysealis hemimelica

Explanation

Dysplasia epiphysealis hemimelica (Trevor disease) is an osteochondroma-like overgrowth of an epiphysis. It is typically unilateral, primarily involves the medial half of the lower extremity joints, and causes localized deformity.

Question 6938

Topic: Bone Tumors
A 15-year-old female presents with an aching pain in her right thigh. Radiographs demonstrate a radiolucent, ground-glass expansile lesion in the proximal femur resulting in a shepherd's crook deformity. If café-au-lait spots with irregular borders are also present, which endocrine abnormality must be screened for?
. Hyperparathyroidism
. Precocious puberty
. Hypothyroidism
. Diabetes insipidus
. Adrenal insufficiency

Correct Answer & Explanation

. Precocious puberty

Explanation

Monostotic or polyostotic fibrous dysplasia combined with café-au-lait spots and endocrine dysfunction defines McCune-Albright syndrome. The most common endocrine manifestation is precocious puberty, driven by an activating somatic mutation in GNAS.

Question 6939

Topic: Bone Tumors

A 5-year-old boy presents with an asymmetric, painless swelling on the medial side of his ankle. Imaging shows an asymmetric cartilaginous overgrowth originating from the medial distal tibial epiphysis. Which of the following best describes the typical histological appearance of this lesion?

. Resembles a classic osteochondroma
. Shows highly atypical chondrocytes
. Consists of woven bone without cartilage
. Fibrocartilaginous cap with cellular stroma
. Organized mature lamellar bone without a cartilaginous cap

Correct Answer & Explanation

. Resembles a classic osteochondroma

Explanation

Trevor disease (dysplasia epiphysealis hemimelica) is characterized by an osteochondroma-like overgrowth of a portion of the epiphysis, typically on the medial side of the lower extremity. Histologically, it is virtually indistinguishable from a classic osteochondroma.

Question 6940

Topic: 10. Pathology and Oncology

A 4-year-old boy presents with anterior bowing of the left tibia. Radiographs reveal an expansile, osteolytic lesion confined to the anterior cortex of the tibial diaphysis with sclerotic margins. Immunohistochemical staining of a biopsy from this lesion is most likely to be positive for which of the following markers, helping distinguish it from fibrous dysplasia?

. S-100
. Vimentin
. Cytokeratin
. CD99
. Desmin

Correct Answer & Explanation

. Cytokeratin

Explanation

Osteofibrous dysplasia occurs almost exclusively in the tibia and fibula, often presenting with anterior bowing. Unlike fibrous dysplasia, the spindle cells in osteofibrous dysplasia consistently stain positive for cytokeratin.

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