p.9
Bone Tumors and Tumor-like Lesions
Which gender is more frequently affected by osteochondromas?
Men, who are affected three times more often than women.
p.3
Genetic Disorders Affecting Bone Development
Which types of collagen mutations are mentioned as affecting bone structure?
Types II, IX, X, and XI collagen.
p.3
Acquired Bone Disorders
What characterizes osteopetrosis?
Reduced bone resorption and diffuse symmetric skeletal sclerosis due to impaired osteoclast function.
p.2
Bone Development and Ossification
What is the sequence of events in the BMU?
Osteoclast attachment and resorption, osteoblast attachment and proliferation, matrix synthesis.
p.1
Bone Structure and Function
What are the primary functions of bones?
Mechanical support, transmission of forces, protection of viscera, mineral homeostasis, and niche for blood cell production.
p.2
Genetic Disorders Affecting Bone Development
What is dysostosis?
Localized problems of mesenchyme migration and condensation, often due to mutations in transcription factors.
p.7
Acquired Bone Disorders
What is sclerosing osteomyelitis of Garre associated with?
Extensive new bone formation that obscures much of the underlying osseous structure.
p.8
Bone Tumors and Tumor-like Lesions
What is the bimodal age distribution of osteosarcoma?
75% occur in persons younger than 20 years old, and 25% occur in older adults with predisposing conditions.
p.8
Bone Tumors and Tumor-like Lesions
Where do osteosarcomas usually arise?
In the metaphyseal region of long bones, particularly around the knee (distal femur, proximal tibia).
p.4
Bone Development and Ossification
What nutritional deficiency is common in adolescent girls during rapid bone growth?
Insufficient calcium intake.
p.4
Hormonal Influences on Bone Health
What hormonal change occurs postmenopausally that affects bone mass?
Estrogen deficiency leads to increased bone resorption.
p.8
Bone Tumors and Tumor-like Lesions
What is the most common subtype of osteosarcoma?
Primary, intramedullary, osteoblastic, and high grade, arising in the metaphysis of long bones.
p.9
Genetic Disorders Affecting Bone Development
What hereditary condition is associated with multiple osteochondromas?
Multiple hereditary exostosis syndrome, an autosomal dominant hereditary disease.
p.1
Bone Matrix Composition
What is osteoid primarily composed of?
Predominantly Type I collagen with small amounts of glycosaminoglycans and other proteins.
p.4
Acquired Bone Disorders
What is the best diagnostic method for osteoporosis?
Dual energy x-ray absorptiometry, quantitative CT, or biopsy.
p.7
Acquired Bone Disorders
What is the typical radiographic finding in osteomyelitis?
A lytic focus of bone destruction surrounded by a zone of sclerosis.
p.10
Bone Tumors and Tumor-like Lesions
What is the clinical course for aggressive malignancies?
They are treated with neoadjuvant chemotherapy and surgical excision, with a 5-year survival of 75%.
p.4
Bone Homeostasis and Remodeling
What type of exercises are more effective for increasing bone mass?
Resistance exercises such as weight training.
p.10
Bone Tumors and Tumor-like Lesions
Where do Giant Cell Tumors typically arise?
In the epiphysis, mostly around the knee (distal femur, proximal tibia).
p.10
Bone Tumors and Tumor-like Lesions
What is the morphology of an Aneurysmal Bone Cyst (ABC)?
It has multiloculated blood-filled cystic spaces and is often eccentric and expansile.
p.10
Bone Tumors and Tumor-like Lesions
What is the common age group affected by Primary Aneurysmal Bone Cysts?
Generally occurs during the first two decades of life.
p.10
Bone Tumors and Tumor-like Lesions
What are Fibrous Cortical Defects?
Common metaphyseal fibrous defects found in 30-50% of children older than 2 years.
p.8
Genetic Disorders Affecting Bone Development
What genetic mutations are associated with enchondromas?
Heterozygous mutations in IDH1 and IDH2 genes.
p.3
Bone Development and Ossification
What are the morphological characteristics associated with certain bone disorders?
Marked cortical thinning, attenuated trabeculae, improper modeling, and persistent foci of hypercellular woven bone.
p.4
Bone Homeostasis and Remodeling
How does reduced physical activity affect bone health?
It increases the rate of bone loss.
p.7
Acquired Bone Disorders
What type of arthritis can result from epiphyseal infections in infants?
Septic and suppurative arthritis.
p.7
Acquired Bone Disorders
What does infection in vertebrae destroy?
Hyaline cartilage and intervertebral discs.
p.7
Acquired Bone Disorders
What stimulates osteoclastic bone resorption after the first week of infection?
Chronic inflammatory cells.
p.5
Acquired Bone Disorders
What are the two types of conditions mentioned in the clinical course?
Monostonic (15%) and Polycystonic (85%).
p.2
Genetic Disorders Affecting Bone Development
What are common forms of dysostosis?
Aplasia (absence of bone), supernumerary digits (extra bones), syndactyly (abnormal fusion of bones).
p.5
Acquired Bone Disorders
What complication can arise from microfractures or bone overgrowth?
Compression of spinal and cranial nerve roots.
p.1
Bone Matrix Composition
What imparts hardness to the bone matrix?
The inorganic moiety hydroxyapatite.
p.4
Acquired Bone Disorders
What is senile osteoporosis characterized by?
Attenuated cellular response to growth factors and low turnover variant.
p.2
Bone Development and Ossification
What is the bone multicellular unit (BMU)?
A unit of coupled osteoblast and osteoclast activity on the surface.
p.1
Bone Structure and Function
How many bones are in the human body?
206 bones, making up 12% of body weight.
p.2
Bone Homeostasis and Remodeling
What regulates the BMU?
Cell-cell interactions and cytokines, including RANK, RANKL, and Osteoprotegerin (OPG).
p.2
Bone Homeostasis and Remodeling
What happens when RANK interacts with RANKL?
It activates the transcription factor NF-κB essential for generation of osteoclasts.
p.4
Acquired Bone Disorders
What is the hallmark of postmenopausal osteoporosis?
Normal bone histology that is decreased in quantity.
p.6
Fracture Healing and Complications
What is osteonecrosis?
Avascular necrosis that often stems from fractures or corticosteroid administration.
p.10
Genetic Disorders Affecting Bone Development
What syndromes are associated with Polyostotic Fibrous Dysplasia?
Mazabraud Syndrome and McCune Albright Syndrome.
p.8
Bone Tumors and Tumor-like Lesions
What are chondromas?
Benign tumors of hyaline cartilage that arise within the medullary cavity or on the surface of the bone.
p.7
Acquired Bone Disorders
What is the treatment for osteomyelitis?
A combination of antibiotics and surgical drainage.
p.5
Acquired Bone Disorders
What is a frequent complication related to weight bearing?
Anterior bowing of femur and tibia, leading to secondary osteoarthritis.
p.5
Acquired Bone Disorders
What type of fractures are commonly associated with these conditions?
Chalk Stick-Type Fractures.
p.4
Bone Development and Ossification
What happens to marrow in the mixed phase of Paget Disease?
It is replaced by connective tissue containing osteoprogenitor cells and blood vessels.
p.9
Bone Tumors and Tumor-like Lesions
What is the most common type of chondrosarcoma?
Conventional chondrosarcoma, which is hyaline cartilage producing.
p.9
Bone Tumors and Tumor-like Lesions
What imaging characteristic is associated with chondrosarcomas?
Calcified matrix appears as foci of flocculent densities.
p.5
Acquired Bone Disorders
What are the manifestations of Renal Osteodystrophy?
Osteopenia, Osteoporosis, Osteomalacia, Secondary hyperparathyroidism, Growth retardation.
p.10
Bone Tumors and Tumor-like Lesions
What is the morphology of tumors that arise in the medullary cavity?
They invade the cortex, periosteum, and soft tissue, often with hemorrhage and necrosis.
p.2
Bone Development and Ossification
When is peak bone mass achieved?
In early adulthood after cessation of skeletal growth.
p.3
Bone Homeostasis and Remodeling
What is the primary defect in osteopetrosis?
Interference with the acidification process of the osteoclast resorption pit.
p.3
Bone Development and Ossification
What morphological features are associated with osteopetrosis?
Lack of medullary canal, bulbous ends of bones, and Erlenmeyer flask deformity.
p.5
Acquired Bone Disorders
What percentage of cases are asymptomatic and discovered incidentally?
Most cases are asymptomatic.
p.3
Acquired Bone Disorders
What is the difference between osteopenia and osteoporosis?
Osteopenia refers to decreased bone mass, while osteoporosis is severe osteopenia that significantly increases fracture risk.
p.4
Fracture Healing and Complications
What is the most common fracture associated with osteoporosis?
Vertebral fractures, particularly in the thoracic and lumbar regions.
p.1
Bone Matrix Composition
What are the two histologic forms of bone matrix?
Woven bone (rapidly produced, less structural integrity) and lamellar bone (slowly produced, better structural integrity).
p.1
Bone Cell Types and Functions
What are osteoprogenitor cells?
Pluripotential mesenchymal cells on bone surfaces that differentiate into osteoblasts.
p.2
Genetic Disorders Affecting Bone Development
What is Thanatophoric Dysplasia?
The most common lethal form of dwarfism, characterized by microlemic shortening of limbs and respiratory insufficiency.
p.9
Bone Tumors and Tumor-like Lesions
What is the clinical course of symptomatic osteochondromas?
They are cured by simple excision.
p.1
Bone Development and Ossification
What is intramembranous ossification?
The development of flat bones directly from a fibrous layer of tissue without a cartilage mold.
p.9
Bone Tumors and Tumor-like Lesions
What is Ewing Sarcoma?
A malignant bone tumor characterized by primitive round cells without obvious differentiation.
p.3
Acquired Bone Disorders
What is osteopetrosis also known as?
Marble bone disease or Albers-Schönberg disease.
p.10
Bone Tumors and Tumor-like Lesions
What is the pathogenesis of Giant Cell Tumors?
Neoplastic cells are primitive osteoblast precursors, and the tumor contains non-neoplastic osteoclasts.
p.6
Fracture Healing and Complications
What growth factors are released by cells during fracture healing?
PDGF, TGF-β, and FGF stimulate bone cells.
p.6
Fracture Healing and Complications
What is the soft tissue callus?
A fusiform, uncalcified tissue that provides an anchor between the ends of bones but lacks rigidity.
p.1
Bone Matrix Composition
What are the two main components of the bone matrix?
Organic component (osteoid, 35%) and mineral component (65%).
p.8
Bone Tumors and Tumor-like Lesions
What is the typical treatment approach for osteosarcoma?
A multimodality approach including neoadjuvant chemotherapy followed by surgery.
p.9
Bone Tumors and Tumor-like Lesions
At what age are solitary osteochondromas typically diagnosed?
Late adolescence and early adulthood.
p.1
Bone Matrix Composition
What role do osteopontin and osteocalcin play in bone?
They are unique to bones and play a role in bone formation, mineralization, and calcium homeostasis.
p.4
Acquired Bone Disorders
What are the three phases of Paget Disease?
Initial osteolytic stage, mixed osteoclastic-osteoblastic stage, and burned out quiescent osteosclerotic stage.
p.4
Bone Structure and Function
What is a hallmark morphology of Paget Disease?
A mosaic pattern of lamellar bone.
p.4
Bone Homeostasis and Remodeling
What characterizes the initial lytic phase of Paget Disease?
Waves of osteoclastic activity and numerous resorption pits.
p.1
Bone Cell Types and Functions
How do osteocytes communicate?
Through an intricate network of dendritic cytoplasmic processes via tunnels known as canaliculi.
p.5
Genetic Disorders Affecting Bone Development
What is Rickets?
A disorder in children that interferes with bone deposition in growth plates.
p.5
Hormonal Influences on Bone Health
What role does PTH play in calcium homeostasis?
Activates osteoclasts, increasing bone resorption and serum calcium levels.
p.3
Acquired Bone Disorders
What dental imperfection is noted in the text?
Misshapen blue-yellow teeth.
p.8
Bone Tumors and Tumor-like Lesions
Which gender is more commonly affected by osteosarcoma?
Men, with a ratio of 1.6:1.
p.6
Fracture Healing and Complications
What is the initial response to a fracture?
Rupture of blood vessels results in hematoma filling the fracture gap and surrounding the bone injury.
p.6
Fracture Healing and Complications
What role does clotted blood play in fracture healing?
It provides a fibrin mesh that seals the fracture site and creates a framework for inflammatory cells, fibroblasts, and new capillaries.
p.3
Genetic Disorders Affecting Bone Development
What are mucopolysaccharidoses?
A group of lysosomal storage diseases caused by deficiencies in enzymes that degrade certain sulfates.
p.9
Bone Tumors and Tumor-like Lesions
What is the most common benign bone tumor?
Osteochondroma, with 85% being solitary.
p.6
Fracture Healing and Complications
What happens to the soft tissue callus after two weeks?
It transforms into a bony callus.
p.6
Fracture Healing and Complications
What are common predisposing factors for osteonecrosis?
Alcohol abuse, Gaucher disease, bisphosphonates, infection, and corticosteroids.
p.2
Genetic Disorders Affecting Bone Development
What causes Brachydactyly types D and E?
Mutations in the homeobox HOXD13 gene.
p.2
Genetic Disorders Affecting Bone Development
What is Cleidocranial Dysplasia?
A condition caused by loss of function mutations in the RUNX2 gene, leading to various skeletal abnormalities.
p.8
Bone Tumors and Tumor-like Lesions
What is an osteochondroma?
A benign cartilage-capped tumor attached to the underlying skeleton by a bony stalk.
p.2
Genetic Disorders Affecting Bone Development
What is Osteogenesis Imperfecta?
A brittle bone disease caused by deficiencies in the synthesis of type I collagen, leading to extreme skeletal fragility.
p.9
Bone Tumors and Tumor-like Lesions
What are chondrosarcomas?
Malignant tumors that produce cartilage.
p.7
Bone Tumors and Tumor-like Lesions
What is the size difference between osteoid osteoma and osteoblastoma?
Osteoid osteoma is less than 2 cm, while osteoblastoma is larger than 2 cm.
p.1
Hormonal Influences on Bone Health
What hormones control bone development?
Growth Hormone, Thyroid Hormone, Indian Hedgehog, Parathyroid hormone-related protein, Wnt, SOX9, RUNX2, and Fibroblast growth factors.
p.10
Bone Tumors and Tumor-like Lesions
What indicates a greater degree of neuroectodermal differentiation in tumors?
The presence of Home-Wright Rosettes.
p.10
Bone Tumors and Tumor-like Lesions
What characterizes a Giant Cell Tumor (Osteoclastoma)?
It is dominated by multinucleated osteoclast-type giant cells and is locally aggressive.
p.8
Bone Tumors and Tumor-like Lesions
What is a common initial symptom of osteosarcoma?
Sudden fracture of the bone.
p.8
Bone Tumors and Tumor-like Lesions
What radiological feature is indicative of an aggressive osteosarcoma?
Codman triangle, which results from the tumor breaking in the cortex and lifting the periosteum.
p.7
Acquired Bone Disorders
What is a Brodie abscess?
A small intraosseous abscess that involves the cortex and is walled off by reactive bone.
p.5
Acquired Bone Disorders
Which areas of the body are primarily involved in these conditions?
Axial skeleton or proximal femur (80%).
p.10
Bone Tumors and Tumor-like Lesions
What is the pathogenesis of Fibrous Dysplasia?
It involves a somatic gain-of-function mutation in the GNAS1 gene.
p.2
Genetic Disorders Affecting Bone Development
What is the difference between dysostosis and dysplasia?
Dysostosis involves localized issues, while dysplasia involves global disorganization.
p.6
Fracture Healing and Complications
How does osteomyelitis typically spread?
Through hematogenous spread, extension from contiguous sites, or direct implantation.
p.1
Bone Cell Types and Functions
What do osteoblasts do?
They are bone-forming cells that synthesize, transport, assemble matrix, and regulate mineralization.
p.6
Fracture Healing and Complications
What happens during acute infection in osteomyelitis?
Bacteria proliferate, inducing neutrophilic inflammation and spreading via the Haversian system.
p.7
Bone Tumors and Tumor-like Lesions
What is a characteristic feature of osteoid osteoma?
Severe nocturnal pain due to PGE2 produced by proliferating osteoblasts.
p.5
Hormonal Influences on Bone Health
What is a hallmark of severe hyperparathyroidism?
Generalized osteitis fibrosa cystica (von Recklinghausen disease of bone).
p.6
Fracture Healing and Complications
What is the most common cause of pyogenic osteomyelitis?
Bacterial infection, primarily Staphylococcus aureus.
p.4
Genetic Disorders Affecting Bone Development
What causes the increased activity of NF-κB in Paget Disease?
Interplay of environmental factors and genetics.
p.1
Bone Cell Types and Functions
What happens to osteoblasts after 3 months?
They become inactive and may remain on the surface or become embedded as osteocytes.
p.5
Genetic Disorders Affecting Bone Development
What is Osteomalacia?
The adult counterpart of Rickets, where bone formed during remodeling is unmineralized.
p.9
Bone Tumors and Tumor-like Lesions
What is the prognosis for grade 1 conventional chondrosarcoma?
5-year survival of 80-90%, rarely metastasizes.
p.9
Genetic Disorders Affecting Bone Development
What genetic translocation is commonly associated with Ewing Sarcoma?
(11;22)(q24;q12) translocation, fusing EWS and FLI1.
p.5
Fracture Healing and Complications
What type of fractures are classified as simple?
Fractures where the overlying skin is intact.
p.9
Bone Tumors and Tumor-like Lesions
Where do osteochondromas develop in the body?
In bones of endochondral origin, near the growth plate of long tubular bones.
p.8
Bone Tumors and Tumor-like Lesions
What is the typical morphology of enchondromas?
Smaller than 3 cm, gray-blue translucent, composed of well-circumscribed nodules of hyaline cartilage.
p.6
Fracture Healing and Complications
What is the typical location of infection in neonates?
Metaphysis or epiphysis due to metaphyseal vessels penetrating the growth plate.
p.5
Acquired Bone Disorders
What is a key diagnostic feature of these bone conditions?
Enlarged, thick, coarsened cortices and cancellous bone.
p.5
Genetic Disorders Affecting Bone Development
What is the fundamental defect in Rickets and Osteomalacia?
Impairment of mineralization and accumulation of unmineralized matrix.
p.5
Hormonal Influences on Bone Health
What are the three interrelated skeletal abnormalities in hyperparathyroidism?
Osteoporosis, Brown Tumors, Osteitis Fibrosa cystica.
p.1
Bone Homeostasis and Remodeling
What happens to bone resorption in the fourth decade of life?
Bone resorption predominates.
p.5
Fracture Healing and Complications
What is a pathologic fracture?
A fracture occurring in bone weakened by underlying disease or tumor.
p.5
Acquired Bone Disorders
What skeletal change occurs due to weakened bone in the skull?
Invagination of the skull base (platybasia).
p.9
Genetic Disorders Affecting Bone Development
What is the pathogenesis associated with hereditary osteochondroma?
Germline loss of function in EXT1 or EXT2 genes, affecting heparin sulfate synthesis.
p.9
Bone Tumors and Tumor-like Lesions
What is the morphology of osteochondromas?
Sessile or pedunculated, 1-20 cm, with a cap of benign hyaline cartilage.
p.7
Acquired Bone Disorders
What is the syphilitic saber shin?
Massive reactive periosteal bone deposition on the medial and anterior surface of the tibia.
p.1
Bone Cell Types and Functions
What is the function of osteoclasts?
They are responsible for bone resorption.
p.1
Bone Development and Ossification
What is endochondral ossification?
The process by which most bones develop from a cartilage mold.
p.9
Bone Tumors and Tumor-like Lesions
What is the common age range for Ewing Sarcoma patients?
Younger than 20 years old.
p.2
Genetic Disorders Affecting Bone Development
What is Achondroplasia?
The most common skeletal dysplasia and a major cause of dwarfism, caused by a gain-of-function mutation in FGFR3.
p.7
Acquired Bone Disorders
What is a characteristic feature of skeletal syphilis?
Bone lesions appear around the 5th month of gestation.
p.2
Genetic Disorders Affecting Bone Development
What is the fundamental abnormality in Osteogenesis Imperfecta?
Too little bone resulting in extreme skeletal fragility.
p.7
Bone Tumors and Tumor-like Lesions
What are osteoid osteoma and osteoblastoma classified as?
Benign bone-producing tumors.
p.9
Bone Tumors and Tumor-like Lesions
What age group is most commonly affected by chondrosarcomas?
Usually in their 40s or older, with some variants affecting younger patients.
