Bone

Question 1

types of bone formation

Answer 1

endochondral ossification - starts with chondrocytes making collagen. osteoclasts/blasts replace collagen with woven, then lamellar bone. long bones, appendicular skeleton, base of skull

membranous ossification - woven bone formed directly from mesenchymal stem cells. later remodel to lammelar; facial and calvarium bones

Question 2

osteopetrosis

Answer 2

defective osteoclasts: failure of normal bone to resorb properly

• bone fills marrow space: pancytopenia
• deficiency in carbonic anhydrase – osteoclasts cant acidify bone well enough
• “marble bone disease” - thick, dense bones prone to fracture

Question 3

Giant cell tumor

age?

location?

behavior?

Answer 3

benign tumor of bone

20-40 yos

located at epiphysial end of long bones – knee common

locally agressive tumor

Question 4

osteochondroma

typical patient?

composition?

Answer 4

most common benign tumor of bone

bone tumor w/overlying cartilage cap

usually a male <25 yo

usually a latera projection of growth plate(metaphysis)

Question 5

osteosarcoma

cell type?

peak incidence?

location?

Answer 5

malignant tumor of osteoblats

bimodal incidence of 10-20(teens) and >65

usually pops up in mataphysis of long bones, around knee

Question 6

predisposing factors for osteosarcoma

Answer 6

pagets disease of bone

bone infarcts

radiation

familial retinoblastoma

Li-fraumeni syndrome(germline p53 mutation)

Question 7

A 14-year-old boy presents with complaints of right knee pain of approximately 2 months’ duration. He remembers falling during soccer training 2 months ago, but the trauma was not severe enough to seek medical attention. Shortly afterward, he started having pain at night or after soccer practice. The pain would initially subside with rest and over-the-counter medication. However, for the past 2 weeks the pain has increased in intensity, causing him to limp. His mother has noticed his right thigh is slightly larger than the left. It is also warm and tender to touch.

Answer 7

osteosarcoma

Question 8

ewing sarcoma

what is it?

what do patients look like?

where does it happen

Answer 8

malignant proliferation of poorly differentiated neuroectodermal cells

young boy (<15 yo)

appears in diaphysis(center) of long bones, pelvis, scapula, ribs

Question 9

chondroma

Answer 9

benign tumor of cartilage

usually arises in medulla of small bones of hands and feet

Question 10

chondrosarcoma

Answer 10

malignant cartilage-forming tumor

arises in medulla of pelvis and central skeleton

Question 11

histology of ewing sarcoma

Answer 11

anaplastic small blue cells(PNET tumor)

onion skinning reaction of periosteal bone

Question 12

ewing sarcoma translocation and fusion protein

Answer 12

t(11;22) causing EWS-FLI1 fusion protein

Question 13

osteoid osteoma

vs

osteoblastoma

Answer 13

osteoid osteoma

benign tumor of osteoid(made by osteoblasts)surrounded by a rim of reactive bone(osteoma)

presents on diaphysis of long bones in young males

osteoblastoma

still a benign tumor of osteoblasts…butttt

larger than osteoid osteoma

arises in vertebrae of young males

bone pain does NOT respond to aspirin

Question 14

what is codman’s triangle

what is it a sign of?

Answer 14

periosteum is lifted off bone and makes a triangle/angle with the normal bone

seen in osteosarcoma

Question 15

which bone tumors commonly present at the distal femur, proximal tibia?

Answer 15

giant cell tumor - epiphysis

osteosarcoma - metaphysis

Question 16

what part of bone do cartilage tumors usually arise?

Answer 16

medulla