bones Flashcards
What is the most commmon genetic form of dwarfisma nd what is it’s pathogenesis?
Achondroplasia (short-limbed dwarfism and macrocephaly)
FGF3 mutation negatively regulates chondrocyte proliferation and differentiation and arrests the development of the growth plate.
Failure of normal epiphyseal cartilage fromatio
What are causes of Nonunion?
Interposition of soft tissues at the fracture site
excessive motion
infection
poor blood supply
What is pseudoarthrosis?
condition in which joint-like tissue is formed
What is involucrum
Viable bone that surrounds necrotic bone (sequestrum) in osteomyelitis
What is the differential for multiple lytic lesions associated with keratin positive cells?
metastatic bone cancer
What metastatic carcinoma tumors prduce mostly lytic lesions?
Thyroid
GI Tract
Kidney
Neuroblastoma
What neoplasms in metatstatic carcinoma tend to produce blastic lesions?
Prostate
Breast
Lung
Stomach
What characterizes osteopetrosis
OC Function Arrest
- The retention of the primary spongiosum with its cartilage cores
- lack of funnelization of the metaphysis
- thickened cortex
Result: short block-like, radiodense bones
What are the most common causes of osteomalacia?
Intinsic disease of he small intestine
Cholestatic disorders of the LIver
Bliary Obstruction
Chronic Pancreatic Insufficiency
Malabsorption of Vit. D- complicates Celiac Disease, Crohn Disease, and Scleroderma
What is definlition of Osteonecrosis? Legg-Calve-Perthes Disease?
Osteonecrosis= Avascular Necrosis
refers to death of bone and marrow in teh absence of inection.
L-C-P refers to osteonecrosis in the femoral head in children- which can lead to join incongruity and severe osteoarthritis
What part of the bone is at higher risk for osteomyelitis and why?
The metaphasis of the long bone
Normally, arterioles enter the calcified portion of the growth plate, form a loop, and then drain into the medullary cavity without establishing a capillary bed. This vascular loop allows slowing and sludging of blood flow, allowing time for bacteria to penetrate the blood vessel walls and etablish an infective focus within the bone marrow.
What is the pathogenesis of a sequestrum/
hematogenous spread:
- bacteria extend in to the endosteal vascular channels that supply the cortex
- then spread throughout the Volkmann and Haversian canals of the cotex.
- pus forms underneath the periosteum- this shears off the perforating the arteries that supply the cortex and then leads to futher necrosis of the cortex.
What is a Brodie abscess
Reactive bone from the periosteum and the endosteum that surrounds and contains the infection
What is Cloaca?
the Hole found in the bone during the formation of a draining sinus
Involocrum
lesion in which periosteal new bone formation forms a sheath around the necrotic sequestrum
Describe the consequences of Cystic Degeneration during the bone resorptive process
It leads to areas of fibrosis that contain reactive woven bone, and hemosiderin-laden macrophages that often display many giant cells, which are actually osteoclasts
What are common sites of neoplastic transformation in Paget Disease
Femur, Humerus, or Pelvis
What three entities are characterized by Langerhan cell proliferation?
- Eosinophilic granuloma (localized form)
- Letterer-Siwe disease (filmniant and fatal genrealized disease)
- Hand Schuller Christian Disease
How are the bones of a Hand schuller-Christian disease patient?
Bony lesions are radio lucent
= Mostlly in teh calvaria, ribs, pelvis, and scapulae
A lesion may infiltrate the retero-orbital space, producing exopthalmos
How does a Hand schuller-Christian disease patient become at risk for DI?
Proliferated Langerhans cells can infiltrate the stalk of the hypothalamus and lead to diabetes Insipidus.
What characterizes Myositis Ossificans?
It is benign
pPeripheral neovasuclarization of a hematoma in the msucle and soft tissue s leads to bone spicule formation (because the local environment is similar to that of an intiial hematoma in a healing fracture)
Where does an osteiod osteoma frequently occur?
Cortex of the diaphysis of the tubular bones of the lower extremity.
Descrie an osteiod osteoma
It is spherical, hyperemic
about 1 cm in diameter and is softer than surrounding bone and esily enucleated at surgery
Reactive sclerotic bone surrounds the nidus (osseous tissue)
What is the most frequent sarcoma encountered after Radiation therapy?
Malignant Fibrous Histocytoma ( a soft tissue tumor- foci of hystiocytes/macrophages)
Describe MFH morphology
Variable
Areas of spindle-shaped tumor cells arrayed in an irregularly whorled (STORIFORM) pattern adjacent to pleomorphic fields
The spindle cells tend to be well differentiated and resemble fibroblasts
Describe a synovial sarcoma
It consists of spindle-shaped mesenchymal cells and cuboidal epithelial-like cells. The latter stain with antibodies to keratin, form glands and clefts, and are presumably epithelial.
How do Enchondromas appear and what are patients with these abnormalities at risk for?
Enchondromas are tumor-like masses of abnormally arranged hyaline cartilage, with zones of proliferative and hypertorphied cartilage.
They exhibit a strong tendency to undergo malignant change into chondrosarcomas in adult life.
What aer the risk factors for osteoprosis?
Vitamin D Deficiency low BMI Hypogonadism Sedentary Lifestyle Glucocoticoid therapy
