Pathology π©Ί Flashcards
what is the definition of Osteomyelitis?
inflammation of bone.
βand BMβ
what are the types of osteomyelitis?
acute or chronic.
causes of acute suppurative osteomyelitis
Hematogenous:
- Organism comes through the blood βthe most important causeβ
Non hematogenous:
- Direct Extension from an adjacent focus.
- Traumatic implantation after an open trauma βdouble fractureβ
which age is mostly affected by acute hematogenous osteomyelitis?
Children
due to:
- High vascularity of the growing bone.
- More liability for trauma with resulting hematoma which is a good cultural media for bacteria.
what are the organisms that cause acute hematogenous osteomyelitis?
- mostly staphylococcus aureus.
- E coli and streptococci in neonates.
what are the bones affected in acute hematogenous osteomyelitis?
Around the knee (lower femur, upper tibia ).
what is the site of acute hematogenous osteomyelitis?
Metaphysis of long bones in children
Due to:
- Actively growing and highly vascular.
- Veins are wide leading to slowing of the blood stream and stasis of bacteria.
In adults the vertebral bodies are commonly affected due to the same cause
Pathogenesis of acute hematogenous osteomyelitis
-
Trauma results in the production of suppurative focus in the metaphysis βdue to rupture of vesselsβ
ββ- - Infection spreads to:
1. the medullary cavity
2. Through the cortex: elevates the periosteum leading to subperiosteal abscess.
3. Infection does not reach the joint cavity as the epiphyseal cartilage is highly resistant to the spread of infection.
ββ- - The inflamed bone becomes necrotic due to:
1. Bacterial toxins.
2. Ischemia caused by inflammatory thrombosis and pressure by exudates.
3. Periosteal elevation causes stretching of cortical blood vessels.
ββ- -
Osteoclasts erode the edges of the necrotic bone, separate it from normal bone. The separated necrotic bone is called Sequestrum.
ββ- - The periosteum around the sequestrum deposits a shell of new bone called involucrum. βdue to stimulation of periosteum by elevationβ
ββ- - involcurum which shows holes called cloaca at sites of rupture of subperiosteal abscess which opens on the skin by multiple sinuses discharging pus.
spread of infection in acute hematogenous osteomyelitis
- the medullary cavity
- Through the cortex: elevates the periosteum leading to subperiosteal abscess.
- Infection does not reach the joint cavity as the epiphyseal cartilage is highly resistant to the spread of infection.
what causes necrosis in inflamed bones of acute hematogenous osteomyelitis?
- Bacterial toxins.
- Ischemia caused by inflammatory thrombosis and pressure by exudates.
- Periosteal elevation causes stretching of cortical blood vessels.
what is sequestrum?
The separated necrotic bone
what is Involcrum?
the deposited shell of new bone
Why is this lesion in the metaphysis?
The location of the lesion depends upon the route by which bacteria gain access to the bone. The most common route is hematogenous. The metaphysis is quite vascular and hence is often the site where infection localizes.
This image shows a specimen curetted at surgery. Note that there is a fragment of mineralized debris surrounded by numerous acute inflammatory cells. The vessels are congested. This is the classic histologic presentation of acute osteomyelitis.
Osteomyelitis of the midshaft of the tibia. A large fragment of necrotic cortex is visible deep within the draining sinus. This necrotic bone is called the sequestrum. The reactive periosteum has formed a collar of reactive bone called the involucrum.
what are the complications of Acute hematogenous osteomyelitis?
- Toxaemia and septicemia.
- Pyemia (thrombophlebitis) circulation of infected thrombi.
- Direct spread of infection to adjacent structures (joints) .
- Pathological fractures.
- Chronicity.
what causes chronic osteomyelitis?
Inadequately treated acute cases may change to chronic
what are the characters of chronic osteomyelitis?
a) Acute inflammatory cells are replaced by chronic ones (lymphocytes + plasma cells)
b) There is increased reparative activity with fibroblastic proliferation.
c) Large acute abscesses are surrounded by dense sclerotic bone and are called Bordie abscesses.
d) The causative organism usually remains dormant in the lesion for years.
e) Rarely chronic osteomyelitis may be complicated by:
1) Secondary amyloidosis.
2) Malignancy in sinus tract (sq.c.c).
what are the complications of chronic osteomyelitis?
Rarely chronic osteomyelitis may be complicated by:
1) Secondary amyloidosis.
2) Malignancy in sinus tract (sq.c.c).
I is tuberculous osteomyelitis rare or common?
- Tuberculous osteomyelitis (a type of chronic osteomyelitis) has become rare in areas of the world where good control of pulmonary and intestinal tuberculosis has been achieved.
- It is still common in many developing countries.
what is the most common site of tuberculos osteomyelitis?
The vertebral column is the commonest site of disease (Pottβs disease of the spine).
what happens in tuberculous osteomyelitis?
Liquefaction of necrotic bones of the vertebral bodies leads to collapse and deformities (kyphosis and scoliosis)
what are the diseases of joints?
Arthritis
- Infectious: suppurative, TB
- Metabolic: Gout (uric acid)
- Degenerative: Osteoarthritis
- Autoimmune Rheumatoid arthritis
Tumors
- Ganglion (synovial cyst)
- Giant cell tumor of tendon sheath (pigmented villo-nodular synovitis)
- Synovial sarcoma
What is a synovial jointοΏΌ?
- A synovial joint is the type of joint found between bones that move against each other, such as the joints of the limbs (e.g. shoulder, hip, elbow and knee, fingersβ¦..)
what are the characteristics of synovial joints?
Synovial joints are characterized by
* They have joint cavity
* Articular cartilage covers the ends of opposing bones
* Synovial membrane lines the joint space.
* Ligaments keep bones together
what are the types of infectious arthritis?
Acute arthritis
- Suppurative due to spread of osteomyelitis.
- It may be traumatic or Part of Rheumatic fever
Chronic Arthritis
- Tuberculosis
- Syphilis
what is the definition of gout (Metabolic arthritis)?
Increased serum uric acid leads to deposition of uric acid crystals in joints, This leads to inflammation with foreign body giant cell reaction (tophi) mainly in the meta-tarso phalengeal joint of big toe
N/E of Gout (Metabolic arthritis)
swollen, inflamed joint of the big toe
M/E of Gout (Metabolic arthritis)
uric acid crystals surrounded by inflammatory cells
what is the definition of Osteoarthritis (Degenerative arthritis)?
A degenerative disease of articular cartilage that may be primary or secondary.
what are the joints affected in osteoarthritis (Degenerative arthritis)?
Large joints e.g Hip joint in males, Knees & hands in females
what is the peak age of osteoarthritis (Degenerative arthritis)?
60-80 years
pathogenesis of osteoarthritis (Degenerative arthritis)
Degenerative changes which may be primary due to aging or secondary to mechanical stress
pathology of osteoarthritis (Degenerative arthritis)
Synovial membrane
- Congestion and non specific chronic inflammation.
Articular cartilage
- The central part undergoes degeneration and separation exposing the underlying bone
Bone
- Thickening and sclerosis of exposed bone.
- Small bony projections are formed at the joint periphery (osteophytes)
what is the definition of Rheumatoid arthritis (Autoimmune arthritis)?
Chronic systemic autoimmune disease affecting peripheral joints and other organs in the body
what are the joints affected in Rheumatoid arthritis (Autoimmune arthritis)?
Small joints of hands and feet
what is the peak age of Rheumatoid arthritis (Autoimmune arthritis)?
30-40 year
which sex is mostly affected by Rheumatoid arthritis (Autoimmune arthritis)?
More in females
pathogenesis of Rheumatoid arthritis (Autoimmune arthritis)
Autoimmune. Production of anti-IgG antibodies (rheumatoid factor) leads to ag-ab reaction initiating inflammatory reaction in the joints.
pathology of Rheumatoid arthritis (Autoimmune arthritis)
Synovial membrane
- Chronic inflammation which creeps over the articular cartilage
- A synovial biopsy reveals prominent lymphoid follicles, synovial hyperplasia, and villous folds (pannus)
- Organization of pannus leads to fibrous ankylosis.
Articular cartilage
- Erosion of the articular cartilage mainly at the periphery.
Bone
- Increased osteoclastic activity and osteoporosis.
compare between osteoarthritis and rheumatoid arthritis according to:
- Definition
- Joints affected
- Peak age
- Sex
- pathogenesis
- synovium
- cartilage
- bone
- systemic effects
N/E of osteosarcoma
- Fusiform mass with hemorrhage and necrosis which occupies the medullary cavity then passes to the bone cortex, and elevates the periosteium.
x-ray appearence of osteosarcoma
Sun ray pattern and Codmannβs triangle
what is the site of osteo-chondroma (Exostosis)?
- Usually originate in metaphysis of long bones near the epiphyseal growth plate, especially around the knee.
- It can occur in bones of pelvis, scapula, ribs and rarely in short tubular bones of hand and foot.
M/E of osteo-chondroma (Exostosis)
cancellous bone with pale blue cartilaginous cap
N/E of chondroma
Grey-blue translucent nodule
M/E of chondroma
Islands of hyaline cartilage containing benign chondrocytes
N/E of chondrosarcoma
Large lobulated mass with bluish tinge
X-Ray of giant cell tumor of bone
Large expansible lytic lesion without peripheral bone sclerosis or periosteal reaction.
what is the shape of plasmacytoma (Multiple myeloma)?
- One lytic lesion = Plasmacytoma (solitary myeloma)
- Multiple lytic lesions = Multiple myeloma
