bone formation + bone tumors + bone disorders Flashcards
bones of axial and limb skeletons are formed by
endochondrial ossification
bones of skull + facial bones are formed by
membranous ossification
bone made by osteoblasts and osteoclasts is first built on a cartilage frame made by chondrocytes in this type of bone formation
endochondrial ossification
no cartilage frame in this type of bone formation
membranous ossification
epiphyseal plates are an example of this type of bone formation
endochondrial ossification
new bone formation in growing long bones→ lengthen bones, once plates fuse, no more growth
sporadic mutation that causes a constitutively active fibroblast growth factor receptor (FGFR3) → inhibits chondrocyte proliferation for endochondrial ossification will cause
achondroplasia
risk factor for achondroplasia
advanced paternal age
what condition is this: proximal limbs shorter than distal limbs limb length disproportionate to trunk length large head relative to limbs frontal bossing bowed tibias normal lifespan + fertility AD mutation - 50% chance offspring will get if spouse has no mutation, 2/3 chance living offpsring will get if spouse is also affected
achondroplasia
benign primary bone tumor in patient 20-40 yo
osteoclastoma
benign primary bone tumor in male
osteochondroma
malignant primary bone tumor in male 10-20 yo
osteosarcoma
malignant primary bone tumor in boy
ewing sarcoma
xray appearance of osteoclastoma
CLean = "soap bubbles" = lytic lesion (osteoclast break down bone matrix) = luscent
xray appearance of osteochondroma
CHondroma = CHunk of bone =
hamartoma (benign tumor of disorganized tissue in normal location) = bone spur with cartilaginous cap
xray appearance of osteosarcoma
SarComa =
Sunburst pattern
Codman’s triangle: elevation of periosteum
most common primary malignant bone tumor in children
osteosarcoma (not multiple myeloma - proliferation of plasma cells in bone marrow in elderly)
xray appearance of Ewing sarcoma
Wing =think Onion rings = “onion skin” (layers of new bone in periosteum)
t(11;22) translocation associated with what primary bone tumor
Ewing Sarcoma
primary malignant bone tumor that is aggressive + early mets but responds to chemo
Ewing Sarcoma
most common benign primary bone tumor
osteochondroma
primary bone tumors that are near the knee
osteoclastoma (benign)
osteosarcoma (malignant)
primary tumors with mets to bones
Permanently Relocated Tumors Like Bones think GU: Prostate Renal cell cancer Testes, thyroid Lung Breast
metastatic tumor that causes lytic bone lesions (break down bone)
lung
breast (lytic or blastic)
metastatic tumor that causes blastic bone lesions (build new bone, disordered, weak, fractures)
prostate
breast (lytic or blastic)
is bone mets or primary bone tumor more common
bone mets
presentation of bone mets
bone pain
epidural spinal cord compression causing neuro sx (BB dysfunction) due to vertebral body lesion
hypercalcemia (lytic lesion)
bone disease caused by osteoblasts working too slowly allowing ↑ bone resorption by osteoclasts →↓ bone mass and Ca matrix →↑ risk of fracture
osteoporosis
bone disease with normal Ca, phosphate, PTH, alk phos
osteoporosis
bone disease common in postmenopausal women
osteoporosis
complications of osteoporosis
vertebral crush fractures: may have acute back pain, loss of height, leads to kyphosis
low trauma fractures (falling to the ground): femoral neck fracture, distal radius fracture
diagnosis of osteoporosis by
DEXA scan - bone mineral density test (T
treatment of osteoporosis
stop smoking (↓ bone density), alcohol, high dose or chronic glucocorticoid steroid use, avoid PPIs (need acid to absorb Ca), H2 blockers
exercise - weight bearing (strain bones → stimulate osteoblasts)
vitamin D + vitamin C
bisphosphonates (inhibit osteoclast resorption,↓ fracture risk)
teriparatide (pulsatile PTH,↓ hip fracture risk)
OTHER tx:
post-menopausal conjugated estrogen (not used soley for osteoporosis due to SE of MI and CVA,↓ hip fracture risk)
if low T, give testosterone (build bones)
SERM (raloxifene) (reduce risk of breast cancer,↓ vertebral fracture risk)
calcitonin (inhibit osteoclast, not as effective as bisphosphonates, no ↓ fracture risk)
denosumab: RANK-L inhibitor (inhibit osteoclast)
bone disease where osteoclasts work too slowly → no bone resorption → thick, dense, disorganized bone → ↑ risk of fracture
osteopetrosis
bone disease caused by a mutation in the osteoclast carbonic anhydrase II → no bone resorption
osteopetrosis
bone disease that may cause:
cranial nerve impingement
palsies due to narrowed foramina
pancytopenia (osteoblasts grow in BM)
osteopetrosis
treatment of osteopetrosis
BMT: osteoclasts are derived from monocytes in BM
xray appearance of osteopetrosis
bones flare at end, bone-in-bone apperance
bone cell that build bone by secreting/laying down collagen and catalyzing the mineralization of the bone matrix
osteoblast
when osteoblast is incorporated into the bone it is called an
osteocyte (in the lacune of bony matrix, contact with each other via canalliculi)
mutlinucleated bone cell that originated from a monocyte/macrophage, and dissolves bone by secreting acid and collagenases for the goal of releasing Ca into serum or promote remodeling after a fracture
osteoclast
bone disease in which osteoclasts break down bony matrix → activates osteoblasts to lay down new matrix
osteoclasts burnout due to excess activity → only osteoblasts are working → disorganized bony architecture
Paget disease of bone
localized disorder of excess bone remodeling/ bone turnover →↑ alk phos (only lab abnormality)
Paget disease of bone
bone disease with increased risk of osteosarcoma
Paget disease of bone
alk phos is a marker
bone formation (reflects osteoblast activity) other types of alk phos: liver, billirubin
bone disease that can cause: bone pain bone deformaties fractures ↑HAT SIZE (thicker bone) hearing loss (narrowing of auditory foramen)
Page disease of bone
bone disease in kids caused by vitamin D deficiency
rickets
bone disease in adults caused by vitamin D deficiency
osteomalacia
bone disease that causes soft bones that bow out
osteomalacia/rickets
bone disease that causes defective mineralization and calcification of osteoid due to vitamin D deficiency →↓ serum Ca
osteomalacia/rickets
what is the name for cystic bone spaces “brown tumors” lined by osteoclasts filled with fibrous stroma + blood
osteitis fibrosa cystica: a bony manifestation of a endocrine disorder
causes of osteitis fibrosis cystica
1° hyperparathryoidism: high PTH → high Ca, low phosphate, high alk phos
type 1A pseudohypoparathyroidism = (Albright hereditary osteodystrophy): PTH resistance at renal tubules →no signal to ↑ Ca reabsorption → low serum Ca, high serum phosphate → low serum Ca is trigger to increase PTH
in both cases: high PTH → excess osteoclast activity → bone tumors, ↓bone mineral density
bone disease in which bone is replaced by collagen + fibroblasts (more collagen than Ca) → irregular bony trabeculae
polyostotic fibrous dysplasia
polyostotic fibrous dysplasia is part of this syndrome:
McCune Albright Syndrome:
precocious puberty
cafe au lait spots
fibrous dysplasia of bone
treatment for osteomalacia/rickets
vitamin D - reversible!
risk factors for osteoporosis
old age smoking steroid use chronic heparin use white or asian race thin build lack of exercise poor Ca/D intake low T or low estrogen (menopause)
