bones

Question 1

What is the most commmon genetic form of dwarfisma nd what is it’s pathogenesis?

Answer 1

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

Question 2

What are causes of Nonunion?

Answer 2

Interposition of soft tissues at the fracture site
excessive motion
infection
poor blood supply

Question 3

What is pseudoarthrosis?

Answer 3

condition in which joint-like tissue is formed

Question 4

What is involucrum

Answer 4

Viable bone that surrounds necrotic bone (sequestrum) in osteomyelitis

Question 5

What is the differential for multiple lytic lesions associated with keratin positive cells?

Answer 5

metastatic bone cancer

Question 6

What metastatic carcinoma tumors prduce mostly lytic lesions?

Answer 6

Thyroid
GI Tract
Kidney
Neuroblastoma

Question 7

What neoplasms in metatstatic carcinoma tend to produce blastic lesions?

Answer 7

Prostate
Breast
Lung
Stomach

Question 8

What characterizes osteopetrosis

Answer 8

OC Function Arrest

1. The retention of the primary spongiosum with its cartilage cores
2. lack of funnelization of the metaphysis
3. thickened cortex

Result: short block-like, radiodense bones

Question 9

What are the most common causes of osteomalacia?

Answer 9

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

Question 10

What is definlition of Osteonecrosis? Legg-Calve-Perthes Disease?

Answer 10

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

Question 11

What part of the bone is at higher risk for osteomyelitis and why?

Answer 11

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.

Question 12

What is the pathogenesis of a sequestrum/

Answer 12

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.

Question 13

What is a Brodie abscess

Answer 13

Reactive bone from the periosteum and the endosteum that surrounds and contains the infection

Question 14

What is Cloaca?

Answer 14

the Hole found in the bone during the formation of a draining sinus

Question 15

Involocrum

Answer 15

lesion in which periosteal new bone formation forms a sheath around the necrotic sequestrum

Question 16

Describe the consequences of Cystic Degeneration during the bone resorptive process

Answer 16

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

Question 17

What are common sites of neoplastic transformation in Paget Disease

Answer 17

Femur, Humerus, or Pelvis

Question 18

What three entities are characterized by Langerhan cell proliferation?

Answer 18

1. Eosinophilic granuloma (localized form)
2. Letterer-Siwe disease (filmniant and fatal genrealized disease)
3. Hand Schuller Christian Disease

Question 19

How are the bones of a Hand schuller-Christian disease patient?

Answer 19

Bony lesions are radio lucent
= Mostlly in teh calvaria, ribs, pelvis, and scapulae

A lesion may infiltrate the retero-orbital space, producing exopthalmos

Question 20

How does a Hand schuller-Christian disease patient become at risk for DI?

Answer 20

Proliferated Langerhans cells can infiltrate the stalk of the hypothalamus and lead to diabetes Insipidus.

Question 21

What characterizes Myositis Ossificans?

Answer 21

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)

Question 22

Where does an osteiod osteoma frequently occur?

Answer 22

Cortex of the diaphysis of the tubular bones of the lower extremity.

Question 23

Descrie an osteiod osteoma

Answer 23

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)

Question 24

What is the most frequent sarcoma encountered after Radiation therapy?

Answer 24

Malignant Fibrous Histocytoma ( a soft tissue tumor- foci of hystiocytes/macrophages)

Question 25

Describe MFH morphology

Answer 25

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

Question 26

Describe a synovial sarcoma

Answer 26

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.

Question 27

How do Enchondromas appear and what are patients with these abnormalities at risk for?

Answer 27

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.

Question 28

What aer the risk factors for osteoprosis?

Answer 28

Vitamin D Deficiency
low BMI
Hypogonadism
Sedentary Lifestyle
Glucocoticoid therapy