Bones IV Flashcards
1
Q
What is exostosis?
A
- benign bony growth projecting outward from the outer surface of a bone
- by convention, an exostosis is a nodular growth
2
Q
What is an osteophyte?
A
- another term for exostosis
- however, the term osteophyte is, by convention, used to describe a small bony outgrowth at the periphery of a joint, usually in association w/ degenerative joint disease
3
Q
What is a enthesophyte?
A
- a small exostosis at the site of attachment of a ligament, tendon, or joint capsule (an enthesis)
4
Q
What is a enostosis?
A
a benign bony growth w/in the medullary cavity of a bone
5
Q
What is hyperostosis?
A
- by convention, is used to indicate that the dimension of a bone has increased (that a bone is thickened along 1 or more periosteal surfaces)
- use of the term hyperostosis implies a more-than-less uniform thickening of bone along a periosteal surface rather than nodular growths, which are referred to as exostoses
6
Q
What are the different types of proliferative lesions in bone?
A
- hypertrophic osteopathy (HO)
- osteochondromas & multiple cartilaginous exostoses (MCE)
- craniomandibular osteopathy
- calvarial hyperostotic syndrome
- deforming cervical spondylosis
7
Q
What is hypertrophic osteopathy?
A
- aka hypertrophic pulmonary osteopathy or hypertrophic osteoarthropathy (but NOT metaphyseal osteopathy, aka hypertrophic ostodystrophy)
- it is most commonly recognized in dogs but DOES OCCUR IN OTHER MAMMALS
- the disease involves progressive periosteal new bone formation along the bones of the distal limbs
- the lesions of the bone are associated w/ a concurrent disease, usually an intrathoracic neoplasm (therefore hypertrophic osteopathy may be a paraneoplastic syndrome) or inflammation
- the lesions of the bone will usually regress if the concurrent disease is treated successfully
8
Q
What are osteochondromas or multiple cartilaginous exostoses?
A
- have been described in people, Eq, Ca, & possibly Fe
- it is an inherited disease in people, Eq, & probably Ca
- lesions consist of masses of trabecular bone w/ a cartilaginous cap projecting from the metaphyseal areas of endochondral bones
- the trabecular bone of each mass is continuous w/ that of the bone of origin
- the masses appear early in life, increase in size through endochondral ossification of the cartilaginous cap, & stop growing at skeletal maturity
9
Q
What is craniomandibular osteopathy?
A
- aka “lion jaw”
- a heritable disease of West Highland White, Scottish, & Cairn terriers
- other breeds of Ca have been affected, but rarely
- the pathogenesis is unknown
- lesions consist of periosteal new bone production (exostoses of hyperostosis) of the mandible, tympanic bullae, & other bones of the head
10
Q
what is calvarial hyperostotic syndrome?
A
- is a condition that is most often described in young bullmastiff dogs
- the lesions involve progressive, asymmetric cortical thickening of the bones of the skull cap (frontal, parietal, temporal, & occipital bones)
- the cause is not known
11
Q
what is deforming cervical spondylosis?
A
- a condition most recognized in ADULT Fe caused by prolonged exposure to excess vitamin A
- the exposure is most often due to feeding an unconventional diet, usually beef liver
- as the name of the condition suggests, the lesions involve the formation of extensive & confluent exostoses over the dorsal & lateral aspects of the cervical vertebrae, often leading to ankyloses (ankylosing spondylosis)
- sometimes, in more severe cases, the occipital bone, cranial thoracic vertebrae, sternum, & proximal forelimbs can be affected
- if the intervertebral foramina are reduced in size, which is common, there can be compression & degeneration of the associated nerves
12
Q
What are the 3 types of benign primary neoplasms?
A
- osteoma
- chondroma
- ossifying fibroma
13
Q
describe neoplastic diseases of bone (the organ):
A
- may be primary or secondary
- primary neoplasms of bone arise most often from bone (the tissue) - about 85% - & less often from cartilage - ~ 15%
- other primary neoplasms of bone occur rarely & may arise from fibrous tissue, blood vessels, adipose, etc.
- primary neoplasms may be benign or malignant
14
Q
What are osteomas?
A
- uncommon, benign neoplasms that grow slowly but progressively by intramembranous ossification
- they usually arise from bones of the head
- they are composed of well-differentiated trabecular bone
15
Q
What is a chondroma?
A
- uncommon, slow growing, benign neoplasms of hyaline cartilage that usually arise from bones of the head
16
Q
What is an ossifying fibroma?
A
- uncommon & occur as large masses on the mandible or maxilla of Eq & Bo
- they are composed of well-differentiated fibrous tissue that contains scattered spicules of woven bone
- w/ time, a greater proportion of the mass becomes ossified, & it resembles an osteoma
17
Q
What are the 8 types of malignant primary neoplasms?
A
- osteosarcoma
- chondrosarcoma
- fibrosarcoma
- hemangiosarcoma
- giant cell tumour of bone
- multilobular tumour of bone
- maxillary fibrosarcoma
- bone surface neoplasms
18
Q
What are osteosarcomas?
A
- relatively common, usually rapidly growing, malignant tumours in which the neoplastic cells form osteoid or bone
- besides the production of osteoid or bone, growth of osteosarcomas usually cause the destruction (lysis) of preexisting bone
- osteosarcomas are characterized by aggressive local invasion & early metastasis, but not the invasion of joint spaces
- osteosarcomas arise most commonly in the long bones of limbs
19
Q
what is a chondrosarcoma?
A
- not common, grow slowly, cause local destruction of bone, but metastasize late
- defining feature of chondrosarcomas is that the malignant cells produce cartilaginous ECM, but NEVER osteoid or bone
20
Q
What is a fibrosarcoma?
A
- malignant tumors composed of fibroblasts & the CT they produce
- fibrosarcomas arising in bones can result in the destruction of bone
21
Q
What is a hemangiosarcoma?
A
- malignant neoplasms of vascular endothelium that, in this context, arises from w/in a bone
22
Q
What is a giant cell tumor of bone?
A
- refers to a malignant neoplasm of bone marrow stromal cells
- there are many osteoclasts in the lesion, but they are not the neoplastic cells
- these neoplasms used to be called osteoclastomas (but the osteoclasts are not neoplastic)
23
Q
What is a multilobular tumor of bone or canine multilobular osteochondrosarcoma?
A
- uncommon, slow-growing, but often malignant neoplasm of the skull bones of the Ca (& Fe & Eq)
- this tumor tends to be locally invasive & this feature typically leads to the euthanasia of affected dogs
- metastasis has been described but is not common
24
Q
What is a maxillary fibrosarcoma?
A
- occur only in dogs
- they are intriguing neoplasms b/c they have a benign, if not innocuous, histologic appearance but are malignant; mostly invasive, sometimes metastatic
- these so-called histologically low grade fibrosarcomas can also arise in other bones of the head
25
Q
What is a bone surface neoplasm?
A
- neoplasms that arise from the periosteum
- all are malignant, but slower growing & less aggressive than corresponding neoplasms originating from w/in a bone
- tumor types include periosteal osteosarcoma, periosteal chondrosarcoma, periosteal fibrosarcoma, & parosteal osteosarcoma
- periosteal sarcomas invade the underlying cortex while parosteal sarcomas, typically, do not (or do so much later in the disease)
26
Q
Stats of osteosarcomas?
A
- > 8,000 new cases/yr in US
- appendicular skeleton of mature, large & giant breed dogs (~75%)
- front limbs twice as often as hind limbs (“away from the elbow”)
- axial skeleton of small breed dogs
- similar prognosis
- many subtypes: osteoblastic, chondroblastic, fibroblastic, etc.
- < 15% have “detectable” metastasis at diagnosis; 90% die of metastatic disease w/in 1 year
27
Q
What are secondary neoplasms of bone?
A
- malignant neoplasms that usually spread via circulation & begin to grow w/in bones (metastasize to bones)
- bones appear to be involved as sites of metastatic neoplasia b/c of the vascular nature of bone marrow
- metastatic neoplasms in bone can be associated w/ pain, lysis of bone, pathologic fracture, & new bone formation
- why some neoplasms metastatic to bone result in more bone lysis than bone formation, while other neoplasms metastatic to bone result in the reverse effects (more bone formation than bone lysis) is not known
- carcinomas are reported to metastasize to bone more frequently than sarcomas
28
Q
What is a myeloma?
A
- a primary bone marrow neoplasm
- can also affect bone
- the most common type of bone marrow neoplasm to affect bone is so-called multiple myeloma or plasma cell myeloma
29
Q
What are bone cysts & cyst-like lesions?
A
- rare, discrete cavities w/in a bone that may distort the cortex
- the cavity is usually filled w/ fluid or soft tissue
- by definition, a cyst is a closed cavity or sac lined by an epithelium
- the term bone cyst, therefore, is not always accurate as there is no epithelial lining
- so, some authorities use the term ‘cyst-like lesion’ to refer to these lesions
- the presence of a bone cyst may reduce the strength of the bone & may cause lameness
30
Q
What is fibrous dysplasia?
A
- refers to an uncommon lesion found in young animals & probably represents a developmental defect
- it consists of an expanding mass of fibro-osseous tissue that results in the distortion & weakening of the cortex of the affected bone
