Cartilage Forming Tumors Overview

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Questions and Answers

What is the primary characteristic of osteochondromas?

They are benign outgrowths with a mushroom shape. (correct)

They originate from hematopoietic cells.

They frequently metastasize to the lungs.

They are always malignant.

What genetic alteration is primarily associated with osteochondroma?

Mutation of the EXT gene. (correct)

Overexpression of the RUNX2 gene.

Mutation of the TP53 gene.

Deletion of chromosome 13.

What complication can arise due to the growth of osteochondromas?

Fractures of the affected bone.

Increased risk of osteoporosis.

Compression of surrounding tissues and nerves. (correct)

Development of osteosarcoma in all cases.

What is the risk associated with hereditary variants of osteochondromas?

Increased risk for chondrosarcomas. Signup and view all the answers

When do osteochondromas typically stop growing?

After normal skeletal growth is completed. Signup and view all the answers

What type of cartilage does chondroma primarily consist of?

Hyaline cartilage Signup and view all the answers

Where are juxtacortical chondromas typically located?

On the surface of bone Signup and view all the answers

What genetic mutations are most commonly associated with enchondromatosis?

IDH gene mutations Signup and view all the answers

Which of the following statements about chondrosarcoma is true?

The majority of patients are male. Signup and view all the answers

Which characteristic is commonly associated with low-grade chondrosarcoma?

Reactive thickening of the cortex Signup and view all the answers

Which syndrome combines enchondromatosis with the presence of angiomas?

Maffucci syndrome Signup and view all the answers

What radiological feature is associated with high-grade chondrosarcoma?

Destruction of the cortex Signup and view all the answers

What is a common site for enchondromas to occur?

Metaphyses of tubular bones Signup and view all the answers

What type of cancer is Osteosarcoma classified as?

A primary malignancy of bone Signup and view all the answers

In which demographic is Osteosarcoma most commonly diagnosed?

75% of cases occur before age 20 Signup and view all the answers

Which genetic mutations are most frequently associated with Osteosarcoma?

p53 and Rb Signup and view all the answers

What is a common radiological feature seen in Osteosarcoma on X-ray?

Sunray spicules Signup and view all the answers

Which of the following best describes the Codman triangle in relation to Osteosarcoma?

A triangular shadow on X-ray due to aggressive growth Signup and view all the answers

How does the histological appearance of a low-grade Osteosarcoma differ from an advanced-grade Osteosarcoma?

Low-grade has less cellularity with mineralized bone Signup and view all the answers

What structure can Osteosarcoma invade as it progresses?

The medullary canal Signup and view all the answers

Which variant of Osteosarcoma is characterized by areas producing cartilage?

Chondroblastic Osteosarcoma Signup and view all the answers

What is the primary defect in osteoclast function associated with osteopetrosis?

Difficulty in bone decalcification Signup and view all the answers

Which enzyme's defective activity is a common cause of osteopetrosis?

Carbonic anhydrase Signup and view all the answers

What type of bone structure is commonly seen in patients with osteopetrosis?

Sclerotic bone Signup and view all the answers

What is a major consequence of the defective bone remodeling in osteopetrosis?

Fracture risk Signup and view all the answers

Which of the following processes is impaired in osteopetrosis?

Resorption of mineralized bone Signup and view all the answers

Which of the following may contribute to the etiology of osteopetrosis?

Defective proton pumps Signup and view all the answers

Which cell type has difficulty in function due to conditions associated with osteopetrosis?

Osteoclasts Signup and view all the answers

The condition characterized by defects in bone acidification can lead to which disease?

Osteopetrosis Signup and view all the answers

What is a common demographic characteristic of patients diagnosed with osteosarcoma?

Approximately 75% of cases occur before the age of 20. Signup and view all the answers

Which histological feature indicates a high-grade osteosarcoma?

Pleomorphic cells with frequent mitoses and tumor giant cells. Signup and view all the answers

What X-ray finding is associated with aggressive osteosarcoma growth?

Codman triangle indicating periosteal elevation. Signup and view all the answers

Which mutation is linked to hereditary osteosarcoma, increasing risk significantly?

Mutation in the Rb gene. Signup and view all the answers

What characteristic finding on X-ray is described as 'sunray spicules'?

Radiolucent or radiodense regions with irregular margins. Signup and view all the answers

What complication arises from the malalignment of a fractured bone?

Nonunion Signup and view all the answers

Which factor is NOT associated with osteoporosis?

High calcium intake Signup and view all the answers

What condition describes the death of bone tissue due to lack of blood supply?

Osteonecrosis Signup and view all the answers

What is the clinical presentation of osteomyelitis?

Fever, chills, and leukocytosis Signup and view all the answers

Which of the following can lead to pseudoarthrosis?

Nonunion of a fracture Signup and view all the answers

Which bacteria is commonly spread through hematogenous means and associated with osteomyelitis?

Escherichia coli Signup and view all the answers

What is a potential outcome of myositis ossificans?

Bone tissue formation in the muscle Signup and view all the answers

What common condition can arise due to inadequate nutrition affecting bone health?

Osteoporosis Signup and view all the answers

Which of the following describes the term 'osteomyelitis'?

Inflammation of bone and marrow caused by infection Signup and view all the answers

Which condition is characterized by malformed healing of a fracture?

Angulated malunion Signup and view all the answers

What is the primary cause of rickets and osteomalacia in children and adults, respectively?

Vitamin D deficiency Signup and view all the answers

Which histological feature is characteristic of osteomalacia?

Accumulation of unmineralized matrix Signup and view all the answers

What skeletal abnormality is seen in children with rickets?

Widening and lengthening of growth plates Signup and view all the answers

What occurs in adults with osteomalacia leading to skeletal deformities?

Irregular margins in metaphysis Signup and view all the answers

Which factor does NOT contribute to altered vitamin D metabolism?

Excess dietary oil intake Signup and view all the answers

What is typically observed in bone imaging for individuals with osteomalacia?

Pseudofractures or Looser zones Signup and view all the answers

Which of the following is a common feature of rickets but not osteomalacia?

Widening of growth plates Signup and view all the answers

What type of dietary deficiency is most commonly linked with the development of rickets?

Vitamin D Signup and view all the answers

What change is found in the periosteum of bones affected by osteomalacia?

Thickening of periosteum Signup and view all the answers

What role does sunlight exposure play in preventing rickets and osteomalacia?

Promotes vitamin D synthesis Signup and view all the answers

What type of ossification primarily occurs in the maxilla and zygomatic bone?

Intramembranous ossification Signup and view all the answers

Which bone remodeling cells are responsible for resorbing bone?

Osteoclasts Signup and view all the answers

What is a consequence of improper bone remodeling?

Weak, sclerotic bone Signup and view all the answers

During which process is bone added in response to mechanical load?

Bone remodeling Signup and view all the answers

What characterizes the anterior part of the mandible in terms of ossification?

Endochondral ossification Signup and view all the answers

What triggers osteoblasts to deposit bone matrix?

Mechanical loading Signup and view all the answers

Which of the following is considered an acquired disease of bone?

Osteoporosis Signup and view all the answers

Which mechanical stress results in the addition of bone during remodeling?

Compression Signup and view all the answers

What type of bone tumor is classified as a bone-forming tumor?

Osteosarcoma Signup and view all the answers

Which change occurs during osteomyelitis?

Bone necrosis Signup and view all the answers

Study Notes

Cartilage Forming Tumors

Osteochondroma (Exostosis): Benign tumor, most often sporadic but can be inherited through autosomal dominant inheritance (AD) from a mutation in the EXT gene.
- Affects heparan sulfate biosynthesis, which is linked to tumor suppression.
- These tumors are mushroom-shaped and originate from endochondral growth plates, especially near the knee.
- Growth stops once normal skeletal development is complete.
- Can cause pain by compressing surrounding tissues, vessels, and nerves.
- Stalk can fracture.
- Consists of an outer layer of benign hyaline cartilage, capping a benign bony head and stalk.
- Can increase the risk of chondrosarcoma development, particularly in hereditary cases.

Chondroma:

Benign tumor composed of hyaline cartilage.
- Can be located in the medullary canal (enchondroma) or on the bone surface (juxtacortical chondroma).
- Usually solitary, more common in the metaphyses of tubular bones, particularly in the hands and feet.

Enchondromatosis (Multiple Enchondromas):

Rare, non-hereditary form caused by sporadic mutations in the isocitrate dehydrogenase (IDH) genes.
- Two main types:
  - Ollier disease: Only affecting the enchondromas.
  - Maffucci syndrome: Enchondromas plus angiomas (blood vessel malformations).
- Increased risk of malignant transformation.

Chondrosarcoma:

Malignant tumor of cartilage.
- Patients are usually older than 40, with males being more affected than females.
- Common locations: Pelvis, femur, and shoulder girdle.
- Appearance: Large, translucent, gray-white, gelatinous regions with calcification and cystic necrosis.
- Low grade: Reactive thickening of the cortex, mild hypercellularity, and rare mitosis.
- High grade: Cortex destruction, soft tissue mass formation, marked hypercellularity, pleomorphism, bizarre giant cells, and frequent mitosis.

Osteosarcoma:

Most common primary malignant tumor of bone.
- More common in males, with 75% of cases occurring before age 20.
- Older patients may be affected secondary to Paget disease or radiation exposure.
- Highly aggressive.
- Common sites: Long bones of the extremities, particularly near the knee.
- Mutations in p53 (sporadic) and Rb (hereditary, leading to a 1,000-fold increased risk for osteosarcoma).
- X-ray appearance: Masses with radiolucent or radiodense regions, irregular margins due to reactive bone formation (“sunray spicules”). Aggressive growth can penetrate the cortex and lift the periosteum, creating a triangular shadow on X-ray (Codman triangle).
- Tumor characteristics: Large, bulky tumors with areas of hemorrhage, necrosis, and cystic degeneration.
- Low grade: Malignant cells produce mineralized or unmineralized bone.
- Advanced grade: Less bone/matrix production, more pleomorphic cells, frequent mitosis, and tumor giant cells.

Osteopetrosis

Inherited disorders of osteoclast function
Osteoclasts have difficulty decalcifying and resorbing bone
Osteoclasts normally create an acidic environment in resorption bays (Howship lacunae) to break down bone
Defective bone acidification is the most common cause of osteopetrosis
- Defective carbonic anhydrase (CA) enzyme activity
- Defective proton pump
- Defective Cl- channels (Albers-Schönberg disease)
- Retroviral infections can also alter or destroy osteoclasts
Defective bone remodeling leads to accumulation of dense but structurally weak bone ("sclerotic bone")
Sclerotic bone is prone to fracture

Osteogenesis Imperfecta, Osteopetrosis, & Fibrous Dysplasia

These are congenital diseases of bone development
These conditions relate to issues with bone formation and development, affecting the strength and structure of the skeleton.

Osteoporosis, Paget Disease, Rickets, and Osteomalacia

These are acquired diseases of bone
Issues with bone maintenance and integrity, rather than initial development

Rickets and Osteomalacia

Decreased maturation and mineralization of cartilage at the growth plates and osteoid in mature bone
Most common causes:
- Vitamin D deficiency
- Altered vitamin D metabolism
Children: Widening and lengthening of the growth plates
Adults: Loss of mineralization, osteopenia, pseudofractures

Complications of Bone Fractures

Malalignment leading to deformity, delayed union, malunion, or nonunion (pseudoarthrosis)
Joint instability leading to osteoarthritis
Osteonecrosis (avascular necrosis)
Myositis ossificans
Neuralgia

Osteomyelitis

Inflammation of the bone and marrow
Most often caused by an infectious agent: virus, fungus, bacteria, or mycobacteria
Pyogenic bacteria (E.coli, Klebsiella, Pseudomonas, S.aureus) are common culprits
Hematogenous spread: From GI or UG lesions, IV drug use, skin infections
Direct implantation: Open fractures

Osteosarcoma

Most common primary malignancy of bone
More common in males, with 75% of cases occurring before age 20
Can be secondary to Paget disease or radiation exposure in older patients
Commonly found in long bones of the extremities, particularly near the knee
Mutations in p53 (sporadic) and Rb (hereditary) increase risk
X-ray:
- Masses with radiolucent or radiodense regions
- Irregular margins
- "Sunray spicules"
- Codman triangle
Histologically:
- Variable cellularity and bone/matrix production
- Chondroblastic osteosarcoma can produce cartilage

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Explore the characteristics and implications of cartilage forming tumors like osteochondroma and chondroma. This quiz covers their definitions, growth patterns, and potential complications. Ideal for students and professionals in the medical and biological sciences.