LECTURE 8 - finished Flashcards
Define Osteomas
Benign, slow growing neoplasm of membranous bone. It gives rise to well differentiated, mature bony tissue which can be cancellous or compact
How are osteomas classified? Describe these classifications
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
Epidemiology of osteomas:
Common onset = 30-50yoa
F:M = 3:1
What is the aetiology of osteomas
OsteoMas Are Dogii
Developmental anomalies related to Osteoblastomas due to Genetic predisposition Secondary to Inflammation caused by trauma, allergy or Infection
Where are osteomas found?
On membranous bones:
Limited almost exclusively to craniofacial bones
How do osteomas give clinical manifestations?
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
What are the typical manifestations when an osteoma forms in the neck or head?
Breathing problems
Visual disturbances
Hearing disorders
What is an osteoid osteoma?
Small, solitary, benign bone forming tumours that are usually painful
Epidemiology for osteoid osteoma?
M:F = 2:1
Peak age of onset = 5-25yoa
Rare 40+
Where are osteoid osteomas usually found?
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
What is a nidus?
How big are they?
What are they composed of?
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)
What is the most common presentation of osteoid osteomas?
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
What is the clinical course for osteoid osteomas?
Self limiting - usually heals itself within 3-7 years
What do osteoid osteomas look like on xray?
Xray might show a lesion of:
- new bone formation
- surrounding sclerosis
- a well circumscribed, radiolucent ‘nidus’
- surrounding osteopoenia
What is a chondroma? Can they grow much? are they aggressive?
Benign tumours composed of mature hyaline cartilage.
They generally have limited growth potential and are not locally aggressive
What are the 3 classifications of chondromas?
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
What kinds of bones are chondromas usually found? Where in these bones are they most commonly found? And which parts of the body?
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
Outline the pathological process of chondroma formation:
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
What is the clinical picture in chondromas?
Asymptomatic
Local swellings in the short tubular bones of the hands
Path #’s
Pain is rare and can suggest a fracture or malignant transformation
What do chondromas look like on xray?
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)
DDx for chondromas
Bone cyst Giant cell tumour FD Bone infarct Chondrosarcoma
What is the chance that chondromas might have malignant change?
2%
What is the most common benign bone tumour? what % of benign bone and all bone tumours do these account for?
Osteochondroma
35% benign bone tumours
9% all bone tumours
What is another name for osteochondroma?
Exostosis
What age group do osteochondromas usually occur in?
<20yoa
In what parts of the bone are osteochondromas usually seen? Are they usually solitary or multiple?
Fast growing ends of long bone
Iliac crests
Can be solitary or multiple
Outline the pathological process of osteochondromas
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
What % of osteochondromas become malignant and what malignant type do they become?
They become chondrosarcomas
1% of solitary lesions
6% of multiple lesions
What are the radiological findings of an osteochondromas
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
What is giant cell tumour?
A benign but locally aggressive neoplasm
Has large numbers of osteoclast-like giant cells in the background of epithelioid/spindle shaped mononuclear cells.
Epidemiology of giant cell tumours:
20-40yoa
55% are women
More common in oriental countries
What is the typical bone distribution of giant cell tumours? Do they have solitary or multiple lesions?
Most commonly seen in:
- distal femur
- proximal tibia
- proximal humerus
- distal radius
Multiple lesions are rare
What is the clinical picture seen in giant cell tumours? (6)
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)
What are the radiological features of giant cell tumours?
- 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.
What is the classic presentation of a giant cell tumour on xray?
A ‘cystic’ lesions extending right up to the subchondral plate
Where are simple bone cysts usually found? (name 2 bones and the location they’re generally found in)
In the metaphysis of long bones
Proximal humerus
Proximal femur
Describe the pathology of simple bone cysts
They have a lining membrane of thin fibrous tissue
They are usually filled with straw coloured fluid
What are the radiological features a simple bone cyst
Well demarcated Radiolucent In the metaphysis Often extends up to the physeal plate Cortical thinning Expansion of bone
