Pathology of Bones

Question 1

What is the mutation found in achondroplasia?

Answer 1

1) FGF receptor 3 mutation (chromosome 4)
2) Inhibits cartilage proliferation
3) Autosomal dominant

Question 2

Most common form of lethal dwarfism. What is the mutation associated with it?

Answer 2

1) Thanatophoric dwarfism

2) FGFR3 mutation

Question 3

Diseases caused by the absence or mutation of type 1 collagen (alpha 1 and 2 chains)?

Answer 3

1) Osteogenesis Imperfecta

Question 4

What are clinical features to type I osteogenesis imperfecta?

Answer 4

1) Blue sclera
2) Hearing impairment
3) Dental imperfections
4) Fractures in childhood
5) General decrease in bone

Question 5

Rare genetic diseases that are characterized by reduced bone resoprtion and diffuse symmetric skeletal sclerosis; results in abnormally brittle bones What is the cell that is impaired?

Answer 5

1) Osteopetrosis
2) Osteoclasts are impaired
3) Osteoclast impairment is due to carbonic anhydrase II defect

Question 6

Bones lack medullary canal, have persistence of primary spongiosa, and have erlenmeyer flask deformities; bones are sclerotic and thick, but are weak and brittle

Answer 6

Osteopetrosis

Question 7

Is woven bone in adults normal?

Answer 7

No, abnormal

Question 8

What are the three phases of Paget disease of the bone? What is the net result?

Answer 8

1) Initial osteolytic stage
2) Mixed osteoclastic-osteoblastic stage
3) Burnt out quiescent osteosclerotic stage
4) Gain of bone mass, but newly formed bone is disordered and structurally unsound

Question 9

What is the hallmark for Paget disease of the bone?

Answer 9

1) Mosaic pattern of lamellar bone

Question 10

What are complications of Paget disease of the bone?

Answer 10

1) High Output cardiac failure
2) Osteosarcoma
3) Osteoarthritis (due to bowing of the legs)

Question 11

What are the findings of Osteitis fibrosa cystica (severe hyperparathyroidsim)?

Answer 11

1) Increased bone cell activity
2) Peritrabecular fibrosis
3) Cystic brown tumors

Question 12

• Pigeon breast deformity
• Bowed legs
• Rachitic rosary
• Frontal bossing

Answer 12

Ricketsia

Question 13

What skeletal changes can occur with renal osteodystrophy (five total)

Answer 13

1) Increased osteoclastic bone resoprtion (mimics osteitis fibrosa cystica)
2) Delayed matrix mineralization (mimics osteomalacia)
3) Growth retardation
4) Osteopororsis
5) Osteosclerosis

Question 14

How does secondary parathyrodism occur in renal failure?

Answer 14

1) Renal failure results in hyperphosphatemia and decreased 1,25 dihydroxycholecalciferol
2) Increased phosphate and decreased vit. D results in increased release of PTH
3) PTH acts on osteoblasts which act on osteoclasts activating them

Question 15

What is the worst subtype of osteoimperfecta? Which one can you live with?

Answer 15

1) Type II

2) Type I

Question 16

What is the cause of osteopetrosis?

Answer 16

1) Impaired osteoclast activity due to mutation in carbonic anhydrase II

Question 17

How do you differentiate osteoporosis from osteomalacia on radiograph?

Answer 17

1) Osteomalacia has trabeculae are surrounded by wide osteoid seams/osteoid matrix accumulation around trabeculae
2) Osteoporosis has even loss of mineralized and non-mineralized components of bone; trabecular thinning with fewer interconnections

Question 18

What is the difference between senile and postmenopausal osteoporosis?

Answer 18

1) Senile = decreased activity of osteoblasts

2) Postmenopausal = increased activity of osteoclasts

Question 19

How does hyperparathyroidism affect bone remodeling?

Answer 19

1) Increased PTH acts on osteoblasts to express RANKL
2) RANL binds to its receptor on osteoclasts activating them
3) Activated osteoclasts results in dissecting osteitis, cortical bone thinning, and brown tumors

Question 20

What are three causes for osteonecrosis?

Answer 20

1) Idiopathic
2) Trauma
3) Corticosteroid administration

Question 21

What organism are pt. at risk for osteomyelitis if they have sickle cell anema

Answer 21

Salmonella

Question 22

What is the most common cause of osteomyelitis?

Answer 22

Staphylococcus aureus

Question 23

Newly deposited bone forming sleeve of living tissue around the segment of devitalized infected bone

Answer 23

Involucrum

Question 24

What are the radiographic findings of osteomyelitis?

Answer 24

1) Lytic focus of bone destruction surrounded by a zone of sclerosis

Question 25

Describe Pott disease. What is its cause?

Answer 25

1) Myobacterium tuberculosis 2) Infection breaks through the intervertebral discs to involve multiple vertebrae and extend into the soft tissue forming abscesses

Question 26

Dead piece of bone

Answer 26

Sequestreum

Question 27

What phase of syphilis do bone lesions occur?

Answer 27

1) tertiary syphilis

Question 28

Bosselated, round sessile tumor that arises from the subperiosteal surface of the cortex; mainly arise from the face/skull; associated with Gardner syndrome

Answer 28

Osteoma

Question 29

What is the difference between an osteoid osteoma and an osteoblastoma?

Answer 29

1) Osteoid osteoma are less than 2 cm, occur primarily in the appendicular skeleton, and are responsive to aspirin 2) Osteoblastomas are greater than 2 cm, occur primarily in the vertebrae, and are not responsive to apsirin

Question 30

What are the histologic findings of osteoid osteomas and osteoblastomas?

Answer 30

1) Composed of random interconnecting trabeculae of woven bone rimmed by osteoblasts 2) stroma surrounding tumor consists of loose connective tissue that contains many capillaries

Question 31

Malignant mesenchymal tumor in which cancerous cells produce bone matrix; bimodal age distribution; tumor arises in the metaphyseal region of the long bones

Answer 31

Osteosarcoma

Question 32

What is the pathogenesis of osteosarcoma?

Answer 32

1) Associated with mutations of RB and p53

Question 33

What are histologic findings of osteosarcoma?

Answer 33

1) Tumor giant cells with mitoses 2) Tumor cells form bone 3) Extension into the medullary canal 4) Bone has coarse, lace like architecture 5) May have the presence of cartilage

Question 34

What is the Codman triangle and what is it associated with?

Answer 34

1) triangular shadow on radiograph formed by the cortex and raised ends of the periosteum 2) Associated with Osteosarcoma

Question 35

What should you think if a 70 year old has elevated alkaline phosphatase?

Answer 35

Paget disease of the bone

Question 36

Herring bone pattern

Answer 36

Fibrosarcoma

Question 37

What is the most common cause of osteomyelitis in adults? In newborns? In IV drug users? In Sickle cell anemia?

Answer 37

1) Staphylococcus aureus 2) Group B Streptococcus 3) E. coli 4) Salmonella

Question 38

Benign cartilage capped tumor that is attached to the underlying skeleton by a bony stalk; arise from the metaphysis

Answer 38

Osteochondroma

Question 39

Where do osteosarcomas arise?

Answer 39

1) Generally originate in the metaphyseal region of bone

Question 40

Mixed sclerotic and lytic lesions on radiograph

Answer 40

Osteosarcoma

Question 41

How does osteosarcoma spread?

Answer 41

Hematogenously

Question 42

Where do osteosarcomas generally arise and spread extensively through the medullary canal?

Answer 42

Metaphyseal region of long bones

Question 43

Where do osteochondromas develop?

Answer 43

1) They develop only in bones that undergo endochondral ossification (aka long bones) 2) Generally arise at the metaphyseal plate 3) Most common sight is the knee

Question 44

What can an osteochondroma progress to if in the presence of multiple hereditary exostosis?

Answer 44

Chondrosarcoma

Question 45

Benign tumor of the hyaline cartilage that has endochondral origin; generally appear in the short tubular bones of the feet and hands

Answer 45

Chondroma

Question 46

Chondroma that arises within the medullary cavity

Answer 46

Enchondroma

Question 47

Chondroma that arises on the surface of bone

Answer 47

Subperiosteal chondroma

Question 48

What are the radiographic findings of an enchondroma?

Answer 48

1) Oval lucencies that are surrounded by a thin rim of radiodense bone, known as the O ring sign

Question 49

Where do chondroblastomas usually arise? What symptoms does it cause due to its location?

Answer 49

1) Epiphyses 2) Painful 3) May cause joint effusions or restrict joint motion

Question 50

Findings on radiograph for a chondroblastoma

Answer 50

1) Lucencies with spotty calcifications

Question 51

What are the radiograph findings of a chondromyxoid fibroma?

Answer 51

1) Eccentric lucencies that are well delineated from adjacent bone by a rim of sclerosis

Question 52

What are the radiographic findings of a chondrosarcoma?

Answer 52

1) Prominent endosteal scalloping

Question 53

Group of tumors that produce neoplastic cartilage generally located centrally; occurs in >40

Answer 53

Chondrosarcoma

Question 54

Benign tumor that arises during skeletal growth and development that has curvilinear trabeculae of woven bone surrounded by fibroblastic proliferation

Answer 54

Fibrous dysplasia

Question 55

Cellular lesions within bone containing fibroblasts and macrophages; arranged in a storiform pattern

Answer 55

Fibrous cortical defect/non-ossifying fibroma

Question 56

What mutation occurs in the fibrous dysplasia variant pattern that has polyostotic, cafe-au-lait, and endocrine abnormalities? What is the name of this syndrome? What is the most common finding?

Answer 56

1) Gain of function in the GNAS gene 2) McCune Albright syndrome 3) precocious puberty

Question 57

Radiograph shows a ground glass appearance and a well defined marginated lesion

Answer 57

Fibrous dysplasia

Question 58

What is the cause of Ewing sarcoma/primitive neuroectodermal tumor (PNET)

Answer 58

1) Translocation of 11:22

Question 59

Tumor that rose from the medullary cavity commonly found in young white boys that has small, round cells and homer-wright rosettes; mimics infection; express c-myc

Answer 59

Ewing sarcoma or Primitive neuroectodermal tumor

Question 60

What is a homer-wright rosette? What tumor is it associated with?

Answer 60

1) It is a pattern consisting of a circle of tumor cells surrounding a central fibrillary space 2) Found in Ewing sarcoma and primitive neuroectodermal tumors

Question 61

Where do Ewing sarcoma and primitive neuroectodermal tumors arise from?

Answer 61

1) The diaphysis of long bones

Question 62

What is the periosteal reaction of Ewing sarcoma/primitive neuroectodermal tumors?

Answer 62

Production of reactive bone deposited in an onion skin fashion

Question 63

Benign tumor characterized by multi-loculated blood filled cystic spaces; occur in the first two decades of life; appears in the metaphysis

Answer 63

Aneurysmal bone cyst

Question 64

Formation of bone by tumor cells; sunburst pattern by periosteal reaction

Answer 64

1) Osteosarcoma

Question 65

Mass on radiograph that appears as an eccentric, expansile lesion with well defined margions; lesion often has a shell of reactive bone at the periphery

Answer 65

Aneurysmal bone cyst

Question 66

Bone tumor associated with Paget's disease

Answer 66

Osteosarcoma

Question 72

Tumor composed of a mixture of mononuclear cells and a profusion of multinucleated osteoclast type giant cells; "Soap bubble" appearance on xray; found on epiphyseal

Answer 72

Giant cell tumor