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Flashcards in Pathology Deck (62):
1

# of bones in body

206

2

Bone composition?

Inorganic (65%): calcium hydroxyapatiet (strength & hardness)
Organic (35%): collagen (structure)

3

Osteoid

bone that is not mineralized, takes 12-15 days

4

Active cell types in bone?

Osteoprogenitor cell
-pluripotential mesenchymal stem cell
-become osteoblasts under CBFA-1
Osteoblast
Osterclasts
Osteocytes

5

Osteoblast

-from bone
-synthesize osteoid (Type I collagen, 90% of organic part)
-initiate mineralization
-eventually become surrounded by matrix: osteocytes
-mediates osteoclast activity; have PTH receptors

6

Osteoclasts

-remodel bone and resorption
-require cytokines from differentiation
IL-1, IL-3, IL-6, IL-11, GM-CSF, M-CSF
-reside in resorption pits: Howship lacunae
-multinucleated

7

Osteocytes

-sense mechanical stress
-regulate serum calcium & phosphorous
-encased in bone
-communicate through canaliculi: contain osteocytic cell processes

8

Enchondral Bone Formation

-mesenchyme becomes cartilage anlage
-cartilage becomes bone

9

growth plate

cartilage between ossification center

10

anlage

cartilaginous model of the future bone

11

Diaphysis

central portion of long bone

12

Metaphysis

between diaphysis and epiphysis

13

Epiphysis

end of long bones
contains growth plate

14

Osteogenesis Imperfecta

"brittle bone disease"
-common mutations in type I collagen genes
-most are autosomal dominant
-most cases, the teeth are deformed

15

Blue Sclerae

-characteristic with heritable disorders of connective tissue
-problems with Type I collagen

16

Achondroplasia

-reduction in chondrocytes at growth plate
-most common cause of inherited dwarfism, autosomal dominant
-short extremities, normal trunk, large head, normal mentation
-higher level of intelligence than normal population

17

Osteopetrosis

-"marble bone disease," stone-like bones
-osteoclast dysfunction; one variant associated with carbonic anhydrease II deficiency
-bones lack a medullary canal; no trabeculaeor marrow; woven bone leads to fractures
-ends of bones are misshapen and bulbous

18

Osteoporosis

-systemic skeletal disease
-low bone mass
-microarchitectural deterioration of bone tissue leading to enhanced bone fragility and consequent increase in fracture risk
-"porous bone" low hip bone mass & deterioration of bone tissue
-increase risk of fracture-wrist, hip, spine

19

Risk factors of Osteoporosis

-age>70
-menopause < 45
-hypogonadism
-fragility fracture
-hip fracture
-glucocorticoids
-malabsorption
-high bone turnover

20

Paget Disease of Bone

-unbalanced/excessive osteoclast & osteoblast function, increased bone turnover
-osteolytic, mixed osteolytic-soteoblastic, osteoblastic & burnt-out stages
-paramyxocirus and measles virus etiology mostly discredited
-mosaic pattern or lamellar bone; skull & long bone; deforms bones
-painful, mid-adulthood, Northern Europeans
-predisposed to osteogenic sarcoma, chondrosarcoma, & malignant fibrous histiocytoma

21

Paget Disease of Bone
Clinical Points

Thick skull
Deafness
Kyphosis
Pain
Bowed legs

22

Osteomalacia/Rickets

"soft bones"
-failure of the bone to mineralize properly in adult
-inadequate intake of Vit D/calcium
childhood-rickets
adults-osteomalacia (bone pain/fractures)
-surfaces of bone trabaculae are covered by a thicker than normal layer of osteoid
-von Kossa stain: calcified tissue is black

23

Renal Osteodystrophy

-deficiency of 1,25-(OH)2D due to tubular injury: hypocalcemia
-

24

Hyperparathroidism

Primary: adenoma
Secondary: prolonged hypocalcemia w/compensatory hypersecretion
-results in unabated PTH secretion
-detected by osteoblasts
-results in release of mediators that stimulate osteoclasts & bone reabsorption
-cortical bone reabsorption>cancellous bone
-dissecting osteitis

25

Bone Tumors Information

1) age/sex of patient
2) location of lesion
3) radiographic appearance of lesion

26

Primary Bone Tumors in Long Tubular Bones

Malignant Tumors: diaphysis-Ewing's sarcoma and chondrosarcoma, fibrous dysplasia
metaphysis: osteosarcoma and juxtacortical osteosarcomas
benign: osteoblastoma, osteochondroma, non-ossifying fibroma, osteoid osteoma, chondromyxoid fibroma, giant cell tumors

27

Fibrous Dysplasia

Benign, localized developmental arrest
-all components of bone present, do not mature
3 patterns:
-monostotic: single bone involved
-polystotic: multiple bones involved
-McCune Albright syndrome: polyostotic, cafe-au-lait skin pigmentation, endocrinopathies
Polyostotic disease: may transform to soteosarcoma

28

Fibrous Dysplasia X-ray

lucent ground-glass appearance with well demarcated borders
"mothy"

29

Fibrous Dysplasia Histology

loose whorled pattern of fibroblastic tissue with irregular spicules of woven bone
-may contain small islands of cartilage
-can undergo cystic degeneration

30

Fibrous Cortical Defect

30-50% of all children > 2y/o
-developmental defect
-metaphysics of femur and proximal tibia
-1/2 bilateral/multiple
-if > 5-6cm: nonossifying fibroma
-usually undergo spontaneous resolution

31

Fibrous Cortical Defect X-ray

-scooped out with borders which are scalloped and sclerotic
-denser than bone that surrounds them

32

Fibrous Cortical Defect Features

-

33

Fibrous Cortical Defect Pathology

-

34

Nonossifying Fibroma

-large fibrous cortical defect
-sclerotic margin on x-ray
-microscope: "woven mat" or storiform pattern

35

Solitary Bone Cyst

-benign, fluid filled cyst
-thin, lytic bone lesion

36

Aneurysmal Bone Cyst

-bloody, cystic lesions
-"sponge filled with blood"
-can contribute to pathologic fracture

37

Aneurysmal Bone Cyst Features

-not true tumor
-arise from surface of bone
-children/young adults

38

Benign Primary Bone Neoplasms

-greatest frequency 1st 3 decades of life
-usually removed only if pain
-usually found on x-ray
-osteoma, osteoid osteoma, osteochrondroma/chondroma, fibroma, giant cell tumor
-rarely malignant except chrondromas

39

Osteoma

Bone-forming tumor
-round that project from sub- or endosteal surfaces of cortex
-usually solitary, multiple is Gardner's syndrome
-slow growing; usually of little clinical sig unless obstruction

40

Osteoid Osteoma

< 2cm in size

41

Osteochondroma

"exostosis"
-benign, cartilage capped tumor
-attached to underlying skeleton by underlying stalk
-displacement of growth plate in endochrondral bones
-multiple hereditary exostosis AD, rare rise to chondrosarcomas

42

Chondroma

-benign tumor of hyaline cartilage
-Enchondromas: arise in medullary cavity, hands/feet
-juxtacortical: on surface of bone

43

Enchondromas

-usually solitary
-metaphyses of tubular bones: hands and feet
-multiple enchondromas/enchondramatosis
-Ollier disease-nonhereditary
-Maffucci syndrome

44

Enchondromas: X-ray

-radiolucent nodules of hyaline cartilage
-scalloped endosteal surface

45

Giant Cell Tumor of Bone

Multinucleated osteoclast type giant cells

46

Malignant Bone Tumors

rare <1% of all mag tumors
-50% derived from blood forming cells and connective tissue cells

47

Osteosarcoma

"osteogenic sarcoma"
-20% of primary bone cancers, most COMMON primary bone tumor
-75% < 20y/o; smaller peak in elderly - Paget irradiation
-Knee, metaphysis
Retinoblastoma; Rb; MDM2
-painful, progressively enlarging, fracture

48

Osteosarcoma Location

knee>hip>shoulder>jaw

49

Osteosarcoma X-ray

CODMAN TRIANGLE
-periosteal elevation

50

Chondrosarcoma Location

axial skeleton: trunk, pelvis, vertebrae, ribs
-rarely in distal extremities
-diaphysis or metaphysis

51

Chondrosarcoma

Age 35-60
2nd most common primary malignant bone tumor
Surgery, insensitive to chemo
-may arise in association w/preexisting enchondroma

52

Ewing Sarcoma

-small round blue cell tumor
-age 10 to 15, whites
-85% related to PNET
-arise in medulla
-diaphysis of long bones
-onion skin; layers reactive periosteum
-75% 5y survivial with surgery & chemo

53

Metastatic Bone Tumors

-most common tumor in bone
>75% from prostate, breast, lung, kidney
Children: neuroblastoma, Wilms' tumor, osteosarcoma, Ewing sarcoma (extraosseous) and rhabdomyosarcoma
-Usually multifocal:vertebrae, pelvis, ribs, skull, sternum

54

Metastatic Lytic from?

Multiple Myeloma

55

Metastatic Blastic from?

Prostate Cancer

56

Lipomas/Liposarcoma

fatty tumors

57

Dermatofibroma

-"fibrous histiocytoma"
-due to non-cancerous growth of dermal dendritic histiocytic cells
-can arise from minor injury

58

Rhabdomyosarcoma

-tumor made up of cancerous muscle cells called rhabdomyoblasts
-350 cases/year in children < 15y/o
-almost 2/3 develop in children <10
-may arise in any muscle in the body

59

Rhabdomyosarcoma Location

-adj to base of skull
-around eye
-nose/throat
-arms/legs
-urinary system/GU

60

Rhabdomyosarcoma Microscope

-bizarre cells
-elongated "strap" cells

61

Leiomyoma

-uterine leiomyoma with regressive change, wall of uterus is smooth muscle - most common location
-unknown etiology
-cells are clonal & estrogen sensitive
-affect 25-40% reproductive organs
-regress after metapause
-

62

Leiomyosarcoma

-arise anywhere