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YEAR 4 SEMESTER 1 CDM > LECTURE 8 - finished > Flashcards

LECTURE 8 - finished Flashcards

1
Q

Define Osteomas

A

Benign, slow growing neoplasm of membranous bone. It gives rise to well differentiated, mature bony tissue which can be cancellous or compact

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2
Q

How are osteomas classified? Describe these classifications

A

Tissue of origin

  • homoplastic osteoma (growing on bone)
  • heteroplastic osteoma (arising in non-bone tissue)

Specific site within the tissue of origin

  • Central (arise from endosteum)
  • Peripheral (arise from periosteum)
  • Extraskeletal (arise within ST/mm)

Histological characteristics

  • Compact Osteoma: made of dense mature lamellar bone which have no haversian canals and no fibrous component
  • Trabecular Osteoma: cancellous trabecular bone within marrow which is surrounded by cortical bone margin
  • Mixed Osteoma: mixture of compact and mature bone
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3
Q

Epidemiology of osteomas:

A

Common onset = 30-50yoa

F:M = 3:1

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4
Q

What is the aetiology of osteomas

A

OsteoMas Are Dogii

Developmental anomalies
related to Osteoblastomas
due to Genetic predisposition
Secondary to Inflammation 
caused by trauma, allergy or Infection
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5
Q

Where are osteomas found?

A

On membranous bones:

Limited almost exclusively to craniofacial bones

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6
Q

How do osteomas give clinical manifestations?

A

Asually completely asymptomatic:
- clinical manifestations are secondary to pressure on nearby structures
OR
- might manifest as a visible tumour occurring on the external surface of the bone
- ivory hard lumps that are usually painless

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7
Q

What are the typical manifestations when an osteoma forms in the neck or head?

A

Breathing problems
Visual disturbances
Hearing disorders

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8
Q

What is an osteoid osteoma?

A

Small, solitary, benign bone forming tumours that are usually painful

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9
Q

Epidemiology for osteoid osteoma?

A

M:F = 2:1
Peak age of onset = 5-25yoa
Rare 40+

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10
Q

Where are osteoid osteomas usually found?

A

Any bone formed by endochondral ossification (excludes face)

  • tubular bones of the limbs (65-80%)
  • tibia and femur = 50%
  • phalanges = 20%
  • spine = 10% (59% Lx)
  • usually cortical lesions but can occur anywhere in the bone
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11
Q

What is a nidus?
How big are they?
What are they composed of?

A

A nest or place or point in an organism where a lesion, germ or other organism can develop and breed.

They are usually <1cm diameter

They are composed of:
- a central region: a meshwork of dilated vessels,
fibroblasts, osteoclasts, osteoblasts, osteoid and
woven bone (= osteoblastic tissue)
- surrounding fibro-vascular tissue
- outermost layer of mature reactive cortical bone (=
reactive sclerosis)

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12
Q

What is the most common presentation of osteoid osteomas?

A

Little kids present with SPELLS

Scoliosis (10% have spinal manifestations) 
Pain:
joint Effusion
- worse at night
- usually relieved by aspirin
Leg Length discrepancy
Synovitis
Muscle wasting and weakness
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13
Q

What is the clinical course for osteoid osteomas?

A

Self limiting - usually heals itself within 3-7 years

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14
Q

What do osteoid osteomas look like on xray?

A

Xray might show a lesion of:

  • new bone formation
  • surrounding sclerosis
  • a well circumscribed, radiolucent ‘nidus’
  • surrounding osteopoenia
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15
Q

What is a chondroma? Can they grow much? are they aggressive?

A

Benign tumours composed of mature hyaline cartilage.

They generally have limited growth potential and are not locally aggressive

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16
Q

What are the 3 classifications of chondromas?

A

Ecchondroma:

  • periosteal/ subperiosteal/ juxtacortical.
  • occur on the surface of the bone, including the articular surface

Enchondroma:
- arise from diaphyseal medullary cavity

Soft tissue chondroma:
- arise in synovial sheaths of tendons or in the soft tissues adjacent to the tendons in the hands aqnd feet of adults

17
Q

What kinds of bones are chondromas usually found? Where in these bones are they most commonly found? And which parts of the body?

A

They can occur in any bone formed via endochondral ossification

  • Usually at metaphyseal-diaphyseal junction
  • Esp in hands and feet
  • Lesions can be solitary or multiple
18
Q

Outline the pathological process of chondroma formation:

A

Islands of cartilage may persist in the metaphyses of bones which are formed via endochondral ossification.
These islands sometimes begin to grow and resemble a benign tumour.
In time, calcifications may occur within the cartilaginous tumour.
May observe central degeneration within the hyaline cartilage

19
Q

What is the clinical picture in chondromas?

A

Asymptomatic
Local swellings in the short tubular bones of the hands
Path #’s
Pain is rare and can suggest a fracture or malignant transformation

20
Q

What do chondromas look like on xray?

A

A well defined radiolucent area that is centrally placed between metaphysis and diaphysis.
May see some bone expansion
Might also see some flecks of calcification within the radiolucent area (pathognomonic if present)

21
Q

DDx for chondromas

A 
Bone cyst
Giant cell tumour
FD
Bone infarct
Chondrosarcoma
22
Q

What is the chance that chondromas might have malignant change?

A

2%

23
Q

What is the most common benign bone tumour? what % of benign bone and all bone tumours do these account for?

A

Osteochondroma

35% benign bone tumours
9% all bone tumours

24
Q

What is another name for osteochondroma?

A

Exostosis

25
Q

What age group do osteochondromas usually occur in?

A

<20yoa

26
Q

In what parts of the bone are osteochondromas usually seen? Are they usually solitary or multiple?

A

Fast growing ends of long bone
Iliac crests
Can be solitary or multiple

27
Q

Outline the pathological process of osteochondromas

A

They are a developmental lesion. They begin as a small overgrowth of cartilage at the end of an epiphyseal plate.
Ensuing endochondral ossification results in the formation of a bony protuberance which is covered by a “cap” of cartilage.
As the bone grows, the osteochondroma moves further down the metaphysis.
Osteochondromas are slow growing.
Growth of osteochondromas stops and ossification occurs when they parent bone stops growing i.e. puberty

28
Q

What % of osteochondromas become malignant and what malignant type do they become?

A

They become chondrosarcomas

1% of solitary lesions
6% of multiple lesions

29
Q

What are the radiological findings of an osteochondromas

A

Xrays are usually pathognomonic when it finds:

  • a well defined exostosis emerging from the metaphysis
  • the base (pedicle) of the exostosis is continuous with the parent bone
  • it looks smaller than it feels because of the cartilage cap

In a larger lesion we might also see:

  • cartilage degeneration
  • cartilage calcification
30
Q

What is giant cell tumour?

A

A benign but locally aggressive neoplasm

Has large numbers of osteoclast-like giant cells in the background of epithelioid/spindle shaped mononuclear cells.

31
Q

Epidemiology of giant cell tumours:

A

20-40yoa
55% are women
More common in oriental countries

32
Q

What is the typical bone distribution of giant cell tumours? Do they have solitary or multiple lesions?

A

Most commonly seen in:

  • distal femur
  • proximal tibia
  • proximal humerus
  • distal radius

Multiple lesions are rare

33
Q

What is the clinical picture seen in giant cell tumours? (6)

A 
Slight swelling of a long bone
History of trauma
Overlying tissue warmth
Pain at the end of a long bone
Palpable mass
Pathological fractures (10-15% cases)
34
Q

What are the radiological features of giant cell tumours?

A
  • Appears as radiolucent area situated eccentrically at the end of a long bone.
  • The lesion is bound by the subchondral bone plate.
  • The centre of the lesion may have a ‘soap bubble’ appearance.
  • Thinning or ballooning of the cortex.
35
Q

What is the classic presentation of a giant cell tumour on xray?

A

A ‘cystic’ lesions extending right up to the subchondral plate

36
Q

Where are simple bone cysts usually found? (name 2 bones and the location they’re generally found in)

A

In the metaphysis of long bones

Proximal humerus
Proximal femur

37
Q

Describe the pathology of simple bone cysts

A

They have a lining membrane of thin fibrous tissue

They are usually filled with straw coloured fluid

38
Q

What are the radiological features a simple bone cyst

A 
Well demarcated
Radiolucent
In the metaphysis
Often extends up to the physeal plate
Cortical thinning
Expansion of bone

YEAR 4 SEMESTER 1 CDM (12 decks)

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