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Special Pathology II Exam 2
Bone & Joint, Dermatopathology, and Endocrine
180
Veterinary Medicine
Professional
11/12/2011

Additional Veterinary Medicine Flashcards

 


 

Cards

Term
What are the seven basic pathologic categories of bone and joint pathology?
Definition

1. Traumatic diseases

2. Congenital diseases

3. Metabolic disturbances

4. Vascular disturbances

5. Infectious

6. Poorly characterized conditions

7. Neoplastic

Term
What are the five functions of bones?
Definition

1. Structural support

2. Protect organs

3. Attachment for tendon

4. Bone marrow (creation of RBCs and leukocytes)

5. Mineral metabolism (warehouse for calcium and phosphorous)

Term
What are the two types of bone?
Definition

1. Cortical (AKA compact, Haversian, or cortex) bone

2. Cancellous (AKA trabecular, or spongy) bone

Term
What are the three areas of bone and where are they located?
Definition

1. Diaphysis - in the middle

2. Metaphysis - area btwn diaphysis and growth plate

3. Epiphysis - area btwn articular cartilage and growth plate

Term
What is compact bone made of and what is the arrangement of it?
Definition

Made up of osteons (=Haversian system) and circumferential lamellae

Haversian canal at the center of the osteon that is parallel to the long axis of the bone

Volkmann's canals run perpendicular to the long axis of the long bone

Blood vessels and nerve supplies run thru these canals

Term
What is compact bone designed to do?
Definition
Prevent the propagation of microcracks
Term
Where can trabecular bone be found?
Definition
Metaphysis and epiphysis
Term
What are the two types of trabecular bone and what are they based on?
Definition

Based on maturity of bone

1. Lamellar bone (mature bone)

2. Woven bone (immature bone)

Term
What is seen in lamellar bone?
Definition
Orderly, parallel alignment of collagen matrix
Term
What is seen in woven bone?
Definition
Collagen matrix is arranged haphazardly (basket weave)
Term
What type of trabecullar bone is seen in growing animals?
Definition
Woven bone
Term
When is woven bone seen in the adult animal?
Definition
Pathology such as infection, trauma, fracture, neoplasia may cause an appearance of woven bone due to active bone remodeling
Term
What are the three main ways for blood supply to get to bone?
Definition

1. Nutrient arteries

2. Metaphyseal and epiphyseal arteries

3. Periosteal arteries

Term
Where do nutrient arteries go?
Definition
Enters the medullary cavity thru the nutrient foramen and becomes ascending and descending medullary arteries
Term
Where do the metaphyseal and epiphyseal arteries go?
Definition
Anastomoses w/medullary arteries
Term
Where do periosteal arteries go?
Definition

They are the cortex blood supply (plus nutrient/metaphyseal/ epiphyseal arteries)

Join the bone along w/fascial attachment

Term
What is the major/most important blood supply source for the bone?
Definition
Nutrient arteries
Term
What is an osteoblast and what is it used for?
Definition

Arise from bone marrow mesenchymal stem cells

Used for bone formation

Term
What is an osteocyte?
Definition
An osteoblast that has been embedded in mineralized bone matrix, communication through canaliculi
Term
What is an osteoclast and what is it used for?
Definition

A monocyte-macrophage lineage cell

Used for bone resorption

Term
What makes up 90% of bone matrix?
Definition
Type I Collagen
Term
What is Type I Collagen composed of?
Definition
Repeating Glycine-X-Y triplets with Hyp in the Y position
Term
What causes osteogenesis imperfecta?
Definition
A mutation of Type I collagen
Term
What causes scurvy?
Definition
Vitamin C deficiency
Term
What makes up 90% of bone mineral?
Definition
Hydroxyapatite Ca5(PO4)3OH
Term
What do you get if you have a deficit in bone mineral?
Definition
Rickets
Term
What is bone primordia composed of in utero/early stages of gestation?
Definition
There is no mineral component so it is composed of immature pluripotent mesenchymal stem cells
Term
What is the pathogenesis of bone growth in utero/early stages of gestation?
Definition
Starts as immature pluirpotent mesenchymal stem cells with no vascular supply or minerals, these differentiate into cartilage, vascular artery supply (which enters the cartilage thru the nutrient foramen) must be present for the endochondrial ossification of cartilage turning into bone
Term
What is the primary ossification center, when does it occur, and where is it found?
Definition

1. The first site of ossification (formation of bone tissue)

2. Prenatal development

3. Diaphysis/medullary cavity

Term
What is the secondary ossification center, when does it occur and where is it found?
Definition

1. Second place of bone formation

2. Postnatal development

3. Epiphysis

Term
What part of a long bone allows continued postnatal longitudinal growth?
Definition

Growth plate or Physis

 

Term
What type of ossification and growth occurs at the physis?
Definition

1. Endochondral ossification

2. Interstitial growth

Term
What is the pathogenesis of interstitial growth?
Definition

Resting chondrocytes --> Proliferative chondrocytes --> Mature chondrocytes --> Hypertrophic chondrocytes --> Calcified cartilage

How we grow in length

Term
What is chondrodysplasia?
Definition
Disturbance of ossification in the growth plate
Term
What are the two parts of endochondral ossification?
Definition

1. Primary spongiosum

2. Secondary spongiosum

Term
What is primary spongiosum and what occurs during it?
Definition

1. Cartilaginous trabecula, calcified cartilage bars

2. Cartilaginous cores are rapidly replaced by woven bone (osteoid seam)

Cartilaginous bars of the physis tunnel into the metaphysis

Term
What is secondary spongiosum and what occurs during it?
Definition

1. Bony trabecula

2. Primary spongiosa being replaced by lamellar bone (no cartilaginous cores)

Term
What is important about the articular-epiphyseal cartilage complex?
Definition
Endochondral ossification occurs here - it acts like a growth plate and thus also contributes to longitudinal growth
Term
What is the tidal mark in the articular-epiphyseal cartilage complex and who is it seen in?
Definition

1. Line btwn hyaline and calcified cartilage

2. Adult animals

Term
What is the cement line in the articular-epiphyseal cartilage complex and what is it seen in?
Definition

1. Line btwn calcified cartilage and subchondral bone (epiphysis)

2. Adult animals

Term
What is osteochondrosis and who is it seen in?
Definition

1. Any disease that affects the progress of bone growth by killing bone tissue

2. Juvenile animal

Term
How does bone grow in width?
Definition
Intramembranous ossification or appositional growth
Term
How does intramembranous ossification work?
Definition

No cartilage is involved

In the periosteum, there are many pleuripotent osteogenic cells.  They produce osteoblasts and osteoid trajectory w/o endochondrial ossification

Term
How do bones get their shape?
Definition

1. Genetic information

2. Applied load - biomechanical stress is important in "bone remodeling"

Term
At what level is bone modeling done?
Definition
Organ level - macroscopic
Term
What type of change is seen in bone modeling?
Definition
Architectural changes b/c it is macroscopic
Term
What type of bones show bone modeling?
Definition
Growing bones - b/c osteoclasts like areas of high tensile strength
Term
True/False:  Resorption and formation occur in different regions in bone modeling.
Definition
TRUE
Term
What do you get if you have abnormal bone modeling?
Definition
Angular limb deformity
Term
At what level is bone remodeling done at?
Definition
Tissue level - microscopic
Term
True/False: Bone remodeling shows turnover with altering structure.
Definition
FALSE - turnover w/o altering structure
Term
True/False - Bone remodeling is seen throughout life.
Definition
TRUE! - due to metabolism
Term
True/False: Resorption and formation occur in different regions in bone remodeling.
Definition
FALSE - occur at the same site; localized
Term
What is osteopetrosis?
Definition
Rare disease where the bones become harder and denser
Term
What is osteoporosis?
Definition
Thinning of bone tissue and loss of density over time
Term
What is the pathogenesis of bone remodeling?
Definition

Accomplished by BMUs in which bone resorption is coupled with bone formation

Bone formation and bone production occur at same location

Osteoclastic resorption is followed by osteoblastic bone production

Bone remodeling occurs in Basic Multicellular Units (BMU) - BMU consists of: osteoclasts, osteoblasts, vascular supply

Term
Which humoral cues instigate bone resorption?
Definition

Parathyroid hormone is important to instigate bone resorption

However, osteoclasts do not have receptors to sense PTH stimulus - osteoblasts sense PTH and give signals to osteoclasts for bone resorption

Term
What is a fracture?
Definition
A discontinuity of bone
Term
What are the six different types of fracture?
Definition

1. Transverse

2. Oblique

3. Spiral

4. Comminuted

5. Infraction

6. Salter-Harris fracture

Term
What is an infraction fracture?
Definition
Incomplete fracture w/o cortical deformation
Term
What is a Salter-Harris fracture and what is the reason for concern with this type of fracture?
Definition

1. Fracture thru a growth plate

2. May cause a stop in growth (endochondral ossification)

Ex: Radius-Ulna problem where one grows and the other stops

Term
What are the two types of fracture healing?
Definition

1. Direct bone healing

2. Secondary bone healing

Term
What happens in direct bone healing?
Definition

1. Gap healing by bone cells migrating from fracture ends

2. Contact healing

3. BMU is organized into a "cutting cone" of osteoclasts resorbing bone followed by bone formation by osteoblasts which span the gap btwn fracture site

Term
What happens in secondary bone healing?
Definition

1. Employs a combination of intramembranous ossification and endochondrial ossification

2. Seen w/IM (intramedullary) pinning or casting

3. Wider gap w/callus formation

4. Interstitial bone formation due to involvement of periosteum

Term
What is the pathogenesis of fracture healing?
Definition

Hemorrhage, clot formation --> inflammatory cells appear.  Organization and resorption of blood clot --> Mesenchymal cell proliferation, neovascularization --> Callus = osteogenic/chondrogenic reparative granulation tissue

 

Cassie's notes from lecture

Hemorrhage/disruption of vascular supply (hypoxic condition) --> granulation tissue formation --> cartilage --> (if stable condition) --> neovascularization (oxygen/nutrient/growth factors/cytokines) --> endochondral ossification --> bone callus --> bone remodeling --> bone

Term
True/False: If there is a fracture, there is no hemorrhage.
Definition
FALSE! - if there is a fracture, there is hemorrhage - always!
Term
Why do inflammatory cells appear with fractures?
Definition
Because you have hemorrhage so you have the coagulation cascade kicked in so that fibrin and inflammatory cells come in to clean up and stimulate granulation tissue formation
Term
What are the six factors affecting fracture healing?

Definition

1. Blood supply

2. Rigidity of fixation

3. Quality of reduction

4. Age

5. General health and nutrition

6. Local or systemic infection

Term
What are the six factors influencing why a fracture does not heal?
Definition

1. Poor blood supply

2. Too much motion (instability)

3. Bone ends are excessively separated

4. Muscle/fascia is trapped btwn fracture ends

5. Poor nutrition

6. Infection

Term
What are the three complications of fracture union?
Definition

1. Delayed union

2. Malunion

3. Nonunion

Term
What is delayed healing?
Definition
Healing that takes longer than it should
Term
What is malunion?
Definition
healing of fracture w/malignant
Term
What is nonunion?
Definition

Bone union won't occur. 

A fibrous bridge occurs btwn the fracture ends --> motion occurs at the fracture site "pseudoarthrosis"

Term
What is commonly associated with angular limb deformities?
Definition
Rickets
Term
What is the cause of angular limb deformity in foals?
Definition

Etiology is often not apparent

Perinatal factors:  in utero malposition, premature birth, perinatal joint trauma, joint laxity, congenital hypothyroidism --> improper development of cuboidal bones (carpus/tarsus)

Older foals: trauma, nutritional imbalance

Term
What is the common pathogenesis of angular limb deformity in dogs?
Definition

Joint trauma --> premature closure of distal ulnar physis --> continuous growth of the adjacent radius --> asynchronous growth of the radius and ulna --> "bowing" (abnormal bone modeling) --> deformity

Cone shape of distal ulnar physis means it is easily injured and can be injured in many directions

Term
What is chondrodysplasia?
Definition

"bad form" "abnormal formation"

Abnormal cartilage differentiation --> premature cessation of cartilage growth --> development abnormalities of cartilage structure

Term
What is chondrodystrophy?
Definition

"abnormal nourishment"

= chondrodysplasia

Term
What are chondrodysplastic (chondrodystrophic, chondrodystrophoid) breeds?
Definition

breeds that have chondrodysplasia as a characteristic

e.g. dachshund, bulldog, bassett hound, corgi

Term
What is chondrodysplasia characterized by and what breed has familial chondrodysplasia?
Definition

1. Characterized by a generalized or localized lack of coordinated bone and joint development due to abnormal endochondral ossification

2. Familial chondrodysplasia is known in Alaskan malamutes

Common phenotype is shortened front limbs w/deformity (axial skeleton is normal)

Term
What is dwarfism?
Definition
Both selected (dachshund, welsh corgi) and unselected forms are all chondrodysplasia
Term
What is spider lamb syndrome?
Definition

A good animal model to study subset of human dwarfism

An autosomal recessive chondrodysplasia in Suffolk, Hampshire

Term
What is the cause of spider lamb syndrome?
Definition
Dysplasia of ossification centers due to mutation in fibroblast growth factor receptor 3 (FGFR3)
Term
What do you see grossly and histopathically in spider lamb syndrome?
Definition

Gross:  narrow chests, long limbs and neck w/poor muscling, kyphosis, scoliosis, "roman nose" (shortening of the maxilla w/dorsal rounding), limb deformity, pectus excavatum (concavity of sternum)

Histopathology: multiple centers of ossifications w/thickened and disorganized growth plate; haphazardly arranged growth plates (abnormal endochondral ossification)

Term
What is the cause of osteopetrosis "marble bone"?
Definition
Congenital defect in osteoclast function --> failure of bone resorption --> medullary cavity is filled w/unresorbed bone.  Autosomal recessive trait in Red & Black Angus, Hereford, Simmental, and Dutch Holstein-Friesian
Term
What is normal osteoclastogenesis and what is the problem with osteopetrosis?
Definition

1. Bone marrow stromal cells produce CFU-GM and RANKL --> monocyte + RANK --> osteoclast

2. Incomplete osteoclast function/anatomy/production

RANK and RANKL system: osteoblast delivers PTH stimulus to osteoclast.  If there is a problem w/system can't get bone resorption and osteoclast production

Term
What do you see in the metaphysis and diaphysis in osteopetrosis?
Definition

Unresorbed primary spongiosa (cartilaginous trabeculae) fills metaphysis and diaphysis

Said another way - bone marrow is filled w/primary spongiosa - no normal bone remodeling or turnover --> fracture

Term
What is the clinical presentation of osteopetrosis?
Definition

Fracture due to bone fragility

Anemia

Death

Bone is hard, but very fragile and breakable

Term
What is the cause of osteopetrosis-like lesion?
Definition

In utero infection w/BVDV --> ? (possibly increase solube IL-1 inhibitor --> decrease IL-1 --> decrease osteoclastiogenesis) --> retained primary spongiosa

 

Seen in infectious diseases

 

Metaphysis and diaphysis is also filled with bone trabeculae

Term
What is zonal osteopetrotic lesion and what is the pathogenesis?
Definition

1. "Growth retardation lattices" - a band of denser metaphysis

2. Some viruses impaired remodeling by osteoclasts --> transient interruption of bone resorption --> zonal osteopetrotic changes in metaphysis

Term
What are the common animals and etiologies of zonal osteopetrotic lesion?
Definition

1. Cattle - BVDV, lead poisoning

2. Dog - Canine distemper virus

3. Cat - Feline infectious leukemia virus

4. Pig - Classical swine fever virus

Term
What is another name for lead poisoning and what are some common sources?
Definition

1. Plumbism

2. Paint, batteries, and putty cans from rubbish dumps

Term
What is the bone lesion and histopathologic lesion of lead poisoning?
Definition

1. Lead is resorbed by osteoclasts --> interfere w/osteoclastic activity --> metaphyseal osteosclerosis ("lead line" in radiograph)

Osteosclerotic change = white, dense bone

2. Retention of primary spongiosa, intranuclear inclusions

Term
What are various lesions in lead poisoning and what do they do?
Definition

1. Miccrocytic hypochromic anemia, basophilic stippling: interfere w/sulfhydryl binding --> inhibit enzymes involved in heme synthesis (gamma-aminolevulinic acid dehydrase and ferrochelatase)

2. Increase nucleated RBC:  interfere w/5`-nucleotidase

3. Depression, blindness: competes w/Ca++ at the NMJ

4. Renal tubular necrosis:  lead accumulates in proximal renal tubules

5. Centriolobular hepatocellular necrosis: lead accumulates in hepatocytes > inhibit mitochondrial respiration

Term
What is another name for cortical hyperostosis and what is the cause?
Definition

1. "Popeye pigs"

2. Congenital disease of unknown genesis.  Condition is lethal at birth

Term
What is the gross lesion and histopathologic lesion of cortical hyperostosis?
Definition

Gross - thickened limbs (joints are normal)

Histopathology - cortex is thickened by radiating proliferation of periosteal bone

Hyperostosis is pressure from inside to out - get blockage of lymphatic and venous return --> soft tissue is edematous (which is a secondary lesion)

Hyperostosis is the primary lesion - B in bottom picture of slide 38

Term
What is another name for Osteogenesis Imperfecta and what is the cause?
Definition

1. Brittle Bone Disease

2. Hereditary defect of collagen type I production - autosomal recessive trait in Angus cattle

Term
What are the gross and histopathological lesions with osteogenesis imperfecta?
Definition

Gross - affected bones are thin and brittle (osteopenia); type I collagen is also the main type in skin and muscle so see lesions in these organs as weakness; rib cage - callous formation - in utero fracture of infected Angus calf

Histopathology - very thin cortical bone and trabecular bone

Growth plates are typically not affected - b/c cartilage is composed of type II collagen, not type I so growth plate is usually spared

Term
What are metabolic bone diseases?
Definition

A group of conditions affecting the entire skeleton that are of metabolic origin and generally cause a decrease in bone mass ("osteopenia") and a tendency to fracture.

General term for this group is "osteodystrophy"

The diseases imply specific pathologic changes but not specific causes.  In general, they are disorders of calcium, phosphorous, and/or vitamin D metabolism

Term
What is the definition of osteopenia?
Definition

"Deficiency"

Decrease in the amount of bone that does not imply if there is concomitant clinical disease

Term
What is the definition of osteoporosis?
Definition

"Increased porosity"

Decrease in the amount of bone that results in clinical disease

Term
What is the definition of osteomalacia?
Definition

"Softening"

Mineralization defect that results in the accumulation of unmineralized bone (osteoid)

Term
What is the definition of osteosclerosis?
Definition

"Hardening"

Excess mineralization

Term
What are the four metabolic bone diseases?
Definition

1. Osteoporosis/Osteopenia

2. Osteomalacia

3. Rickets

4. Fibrous osteodystrophy

Term
If I say osteoporosis/osteopenia is a metabolic bone disease what does that mean?
Definition

Osteoporosis is the clinical condition

Osteopenia just describes the decreased amount of bone - patient may or may not have clinical symptoms associated w/osteopenia

Term
What are the five causes of osteoporosis/osteopenia and their pathogenesis?
Definition

1. Ca deficiency --> hypocalcemia --> increase PTH --> increase bone resorption

2. Malnutrition (e.g. inanition, inflammatory bowel disease) --> deficiency of protein and mineral, decrease IGF-1 --> decreased bone formation

3. Disuse atrophy: decrease piezoelectric stimuli, decrease mechanical stimuli

4. Glucocorticoid therapy --> decrease calcium absorption from the intestine and increase renal excretion + directly inhibit type I collagen synthesis and osteoblasts

5. [Estrogen deficiency: increase TNF, IL-1, etc. --> increase bone resorption]

Term
What is seen grossly with osteoporosis/osteopenia?
Definition

Thin cortex, trabeculae and fracture

Expanded marrow cavity, increased porosity (due to imbalance of bone resorption > bone formation)

Term
What are osteomalacia and rickets?
Definition
A group of diseases characterized by a defect in bone mineralization
Term
What animal shows osteomalacia?
Definition
Adult animals
Term
What animals show rickets?
Definition
Immature skeletons of growing animals
Term
What is osteomalacia characterized by?
Definition

By wide, unmineralized osteoid seams covering trabecular bones.

Skeletal deformities due to abnormally soft bones.

Mature bones have no open physis so no physeal lesions but is commonly seen at the growth plate

Term
What is affected in rickets?
Definition
The most profound effect is on physis undergoing endochondral ossification
Term
What is the cause of osteomalacia and rickets?
Definition

Vitamin D deficiency

Ca/P imbalance

It is unknown why dietary Ca deficiency does not cause rickets/osteomalacia

Term
What are some common causes of Vitamin D deficiency?
Definition

1. Lack of UV light

2. Advanced liver disease

3. Advanced renal disease

4. Malabsorptive diarrhea

5. Poor diet

Term
What is the pathogenesis of rickets?
Definition
Have normal endochondral ossification and a normal metaphysis --> metaphysis has primary spongiosa but can't get secondary spongiosa (lamellated trabecular bone) --> b/c of failure of mineralization --> can't make healthy bone
Term
What is the gross lesion and histopathological lesions seen with rickets?
Definition

Gross - thick physis (growth plate); "Rachitic rosary" at costochondral junctions

Histopathology - physis is expanded by a thick zone of hypertrophy.  There are retained primary spongiosa (cartilaginous trabeculae)

Term
Animals in what condition commonly develop rickets and why?
Definition
Animals in glass cages will develop rickets b/c the glass will filter out the UV light and the animal can't produce Vitamin D
Term
What are some other names for fibrous osteodystrophy?
Definition

"Rubber jaw"

"Big head"

Term
What is seen grossly with fibrous osteodystrophy?
Definition

The main clinical manifestations is in jaw/maxilla

Big head: symmetrical enlargement of jaw, but bone is resorbed and replaced by fibrous connective tissue which is soft and pliable

Lack of bone = mandible and maxilla are very flexible

Decreased bone mass due to excessive bone resorption and replacement by fibrous tissue

Term
What is seen histopathologically with fibrous osteodystrophy?
Definition

There is very strong osteoclastic bone resorption w/replacement by fibrosis

Lots of osteoclasts

Little cortical bone left due to excessive resorption

Term
True/False:  Osteoclastic resorption is present in rickets/osteomalacia.
Definition
FALSE! - not present in rickets/osteomalacia.  Poorly mineralized bone matrix can't be resorbed b/c osteoclasts can't bind to unmineralized matrix (osteiod)
Term
What hormonal stimulus directly increases bone resorption and leads to fibrous osteodystrophy?
Definition
PTH
Term
What is the pathogenesis of fibrous osteodystrophy?
Definition
Hyperparathyroidism --> bone resorption (osteopenia) and fibrosis
Term
What are the four types of hyperparathyroidism that can cause fibrous osteodystrophy and their pathogenesis?
Definition

1. Renal secondary hyperparathyroidism:  renal failure --> Ca/P imbalance --> stimulates PTH production --> increased osteoclast activity

2. Nutritional secondary hyperparathyroidism:  low Ca, high P (e.g. bran), Vitamin D deficiency; GI issues --> can't absorb Ca --> can't absorb Vitamin D; unknown why some animals w/this develop FOD while others osteoporosis

3. Primary hyperparathyroidism:  hyperplasia or neoplasia

4. Pseudohyperparathyroidism: Parathyroid hormone-related peptide (PTHrP) from neoplasia (lymphosarcoma, anal sac adenocarcinoma) "hypercalcemia of malignancy"; function is the same as PTH but unlikely b/c animal usually doesn't live long enough to be seen clinically

Term
What are the five metabolic disturbances that are nutritional and toxic diseases?
Definition

1. Lead poisoning

2. Vitamin D deficiency - osteomalacia, rickets, fibrous osteodystrophy

3. Vitamin D toxicity

4. Vitamin C deficiency (Scurvy)

5. Vitamin A toxicity

Term
What do you see in lead poisoning?
Definition
Decreased osteoclastic activity --> zonal osteopetrosis
Term
What is the pathogenesis of Vitamin D toxicity?
Definition
Ingestion of excess vitamin D or toxic plant --> decrease PTH; increase calcitonin --> decrease osteoclasts; increase osteoblasts --> no resorption --> increase trabecular bone --> Osteosclerosis; Hyperostosis
Term
What animals will you typically see vitamin C deficiency in and why won't you see it in others?
Definition

1. Humans, non-human primates, and guinea pigs

2. Won't see it in dogs, horses, cows, etc. b/c they have L-gulonolactone oxidase in their livers which is the enzyme necessary to produce endogenous Vitamin C

Term
What is the pathogenesis of Vitamin C deficiency?
Definition

No L-gulonolactone oxidase

Vitamin C deficiency --> impaired hydroxylation of procollagen --> improper cross linking of collagen fibrils --> hemorrhage, thin physis w/inadequate synthesis of cartilage and osteoid

Term
Why is Vitamin C necessary?
Definition

Essential for collagen formation

Collagen fibers: Gly-X-Y triplets with HYP in the Y position (essentially, collagen fiber is repeating Glycine-X-Y amino acid)

Term
What type of collagen fibers does Scurvy affect?
Definition

All collagen fibers including Type I and Type II

Growing animals have very thin growth plates; can see many other clinical symptoms such as hemorrhage b/c vessels are very fragile (vessels are formed by collagen)

Term
What does Vitamin A toxicity cause?
Definition
Failure of normal endochondral ossification and hyperostosis in many other locations
Term
What is the mechanism of Vitamin A toxicity?
Definition

Excessive Vitamin A (enriched grains, sweet potatoes, liver) can cause closure of growth plate (pathogenesis is not known) --> shortening of limbs and vertebral bone deformity

"Hyena disease" - short legs and curved neck w/head tilted to the ground

Term
What is seen histopathologically with Vitamin A toxicity?
Definition
Premature closures of the growth plate
Term
What type of Vitamin A toxicity is reported in cats?
Definition

Vitamin A toxicity w/periarticular exostosis and osteosclerosis

Pathogenesis is unknown but possibly (increase retinoic acid --> increase ets1, a transcription factor --> bone proliferation?)

Term
What are three vascular disturbances of bone?
Definition

1. Legg-Calve-Perthes disease

2. Dry gangrene

3. Hypertrophic (pulmonary) osteopathy

Term
What is Legg-Calve-Perthes Disease?
Definition
Ischemic necrosis of the femoral head and neck
Term
What is the etiology and and susceptible animals of Legg-Calve-Perthes disease?
Definition

1. Unknown etiology

2. Young (4-11 months), growing toy/miniature breeds (about 85% of reported cases are unilateral)

Term
What is the pathogenesis of Legg-Calve-Perthes Disease?
Definition

Vascular compromise to the proximal femoral epiphysis --> necrosis of the trabeculae and marrow tissue

 

What he said:

Disturbance of vascular supply to femoral neck epiphysis --> necrosis --> won't see osteoblast lining on trabecular bone, won't see osteoclasts or fat in bone marrow cavity (on radiograph) --> causes overlying cartilage collapse --> loss of normal round contour of femoral head

Term
What is the pathogenesis of dry gangrene?
Definition

Infarction of an extremity (too tight a bandage on a limb, etc.) --> coagulative necrosis --> mummification

Pyknotic nuclei in the lacunae are all dead b/c the digit was tied down tightly - inhibited normal blood supply

Term
What is seen grossly and histopathologically with hypertrophic (pulmonary) osteopathy?
Definition
Exostosis (periosteal proliferation of bone) on the distal limbs (all 4 can be affected) of animals with (usually) chest masses (e.g. lung tumor)
Term
What is hyperostosis?
Definition
Excessive growth of bone; may lead to exostosis
Term
What is exostosis?
Definition
Periosteal proliferation of bone
Term
What is the pathogenesis of hypertrophic (pulmonary) osteopathy?
Definition

Thoracic lesions thought to lead to chronic hypoxia and/or altered vagal regulation --> increase periosteal blood flow to the extremities

Exostosis goes away when the primary cause is removed

Term
What are the infectious bone diseases?
Definition

1. Infectious osteomyelitis:

Hematogenous osteomyelitis

Direct inoculation osteomyelitis

 

2. Noninfectious osteomyelitis:

Canine hypertrophic osteodystrophy = Metaphyseal osteopathy

Term
What age group is hematogenous osteomyelitis most commonly seen in and what causes it?
Definition

1. Most commonly seen in young animals - probably b/c their host immune response is not very sufficient yet; rare to see in adult animals (except when receiving long-term chemo or glucocorticoids)

2. Caused by bacteria

Term
What is the pathogenesis of hematogenous osteomyelitis?
Definition

Umbilical infection (omphalophlebitis) + FPT --> sepsis --> embolization to blind capillary loops --> osteomyelitis

Terminal branch of the metaphyseal artery makes a hairpin curve subjacent to the growth plate --> common location to see bacterial emboli; reason why you see osteomyelitis foci subjacent to the growth plate

Term
Why is hematogenous osteomyelitis more common in large animals?
Definition
Because of their presentation.  They completely rely on their immunity in their neonatal stage from colostrum.  There there is FPT, animal is very susceptible to infectious diseases.  If there is infection thru umbilical cord, see septicemia and osteomyelitis
Term
Can osteomyelitis occur via systemic mycosis?
Definition
Yes!! But it is rare, if it is systemic you may see a lesion in the bone
Term
What are the ways you can get direct inoculation myelitis?
Definition

Hematogenous route is probably very common

1. Extension:  horse - chronic laminitis, rotation of P3 w/perforation of sole

2. Fracture w/skin penetration

3. Surgery - surgical plate

4. Bite wounds

5. Periodontal disease: cow "lumpy jaw" - granulomatous osteomyelitis and osteolysis w/Actinomyces bovis

Term
What is tricky about hypertrophic osteodystrophy (metaphyseal osteopathy)?
Definition

NEITHER HYPERTROPHIC NOR OSTEODYSTROPHIC!

NOT AN INFECTIOUS BONE DISEASE

DISEASE NAME IS MISLEADING!

Term
What is hypertrophic osteodystrophy and where do you usually see it?
Definition

Unknown etiology!

Usually bilaterally symmetric, a self-limiting disease

Occurence in diverse breeds - genetic, vascular abnormalities

Usually seen in young (2-8 mo) growing large/giant breed dogs

Term
What is seen grossly and histopatholgically with hypertrophic osteodystrophy?
Definition

Gross: metaphysis of long bones - osteomyelitis w/infarction; open physis, growth plate is normal; lesion only in metaphysis - subjacent to growth plate (suppurative inflammation and necrosis in metaphysis, sometimes have microfracture b/c of inflammation and necrosis)

Histopathology: metaphysis infiltrated by suppurative inflammation w/necrosis (necrosis of capillary loops)

Term
Can hypertrophic osteodystrophy go away?
Definition

Yes! - once maturation is completed

Prognosis is good if pain can be monitored

Term
What are two poorly characterized developmental orthopaedic conditions in dogs?
Definition

1. Canine (eosinophilic) Panosteitis

2. Craniomandibular Osteopathy "Lion Jaw"

Term
What is canine panosteitis?
Definition
Bone marrow spaces will be replaced by fibroblasts and osteoblasts.  No inflammatory cell involvement.  Not an osteitis
Term
What is the etiology of canine panosteitis?
Definition

Unknown etiology!

Young (5-12 mo) growing large/giant breeds

75% of reported cases involve German Shepherd dogs

Self-limiting disease in single or multiple bones

Will go away

Term
What is seen histopathologically in canine panosteitis?
Definition

Bone marrow is replaced by fibrovascular tissue w/woven bone

Increase activity of osteoblasts and fibroblasts

Term
What is craniomandibular osteopathy?
Definition
Bilaterally symmetric excessive periosteal new bone formation - exostosis/hyperostosis mainly in mandibular bone, sometimes maxilla and occipital (only skull should be affected)
Term
What breeds do we see this in?
Definition

Growing dogs - Westies, Scotties, Cairn terriers

Unknown etiology but autosomal recessive is suggested in westies

Term
When is lion jaw usually recognized and what do you usually see?
Definition

Usually recognized at 4-7 months old, self-limiting by 11-13 month b/c once animal matures to adult do not see condition; hyperostosis and pain will go away

Usually see pain and discomfort while chewing

Term
What are seven neoplasias seen in bones?
Definition

1. Osteosarcoma

2. Osteoma

3. Chondrosarcoma

4. Chondroma

5. Multilobular tumor of bone

6. Multiple myeloma

7. Other tumors arise from bone

8. Metastatic bone tumors

Term
What is an osteosarcoma?
Definition

A malignant tumor

Most common (malignant) bone tumor (dogs)

Does NOT cross the joint space

Several histologic types but all will make osteoid - must see this to diagnose osteosarcoma

Term
What do you see histopathologically in osteoblastic osteosarcoma?
Definition
All osteoid and osteoblastic neoplastic cells
Term
What do you see histopathologically in chondroblastic osteosarcoma?
Definition

Differentiation of chondrocytes and also osteoblastic differentiation w/osteoid production

(if no osteoid - chondrosarcoma)

Term
What do you see histopathologically with fibroblastic osteosarcoma?
Definition

Looks like fibrosarcoma w/fibular matrix; must see osteoid to diagnose

(if no osteoid, diagnose as fibrosarcoma)

Term
What are three other types of osteosarcomas?
Definition

Telangiectatic

Giant cell type

Poorly differentiated

Term

 True/False:  In dogs, more than 80% of primary bone tumors are osteosarcomas

 

Definition
TRUE
Term
What type of dogs do you see osteosarcomas in?
Definition
Most common in large/giant breeds
Term
Which skeleton is more commonly affected in dogs by osteosarcomas?
Definition

Appendicular (long bones) > axial skeleton

General rule - away from the elbow and close to the knee

Proximal humor, distal radius/ulna (distal radius is a very common location)

Distal femur, proximal tibia

Term
True/False:  Osteosarcomas have a good prognosis.
Definition

FALSE!!

By the time it is diagnosed in dogs, 90% of cases have microscopic metastasis in lungs

Poor prognosis w/frequent metastasis

Term
True/False: In cats, more than 90% of primary bone tumors are osteosarcomas
Definition

FALSE - 70%

 

Term
What skeleton is mainly affected by osteosarcomas in cats?
Definition

Appendicular ~ Axial skeleton

Locally invasive - but slow to metastasis

Term
What is an osteoma and where do you usually find it?
Definition

Counterpart of osteosarcoma

A benign tumor

Rare but most common in the jaws of horses and cows - hard, rounded, disfiguring mass

Term
What is ossifying fibroma?
Definition
An osteoma w/fibroblastic component
Term
What is a chondrosarcoma?
Definition

Accounts for 10% of primary bone tumors in dogs

Neoplasm is composed of disorganized cartilaginous tissue - chondrocyte proliferation

Term
Where do you see chondrosarcomas?
Definition

Most common in large/giant breeds

Flat bones (ribs, nasal cavity, pelvis) are often affected - more common in flat bones, but can be seen in any location

Locally invasive, but slow to metastasize

Term
What is a chondroma?
Definition

Uncommon benign tumor

Neoplasm is composed of well-differentiated cartilage - composed of mature chondrocytes

Usually well-demarcated

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