WT - Bone pathology

Question 1

Osteoporosis

Answer 1

• spongy/cortical bone loss despite nml mineralization and NML Ca, PO4, PTH, Alk phos
• via old age/dec estrogen –> inc bone resorp
• via drugs (steroids, alcohol, anticonvulsants, anticoagulants, thyroid replacement)
• via hypERparathyroidism, hypeRthyroid, mult myeloma, malabsorption, anorexia)
• vertebral compression fractures, Colles (distal radius)

dx: DEXA scan, T-score = -2.5 or fragility fracture
tx: bisphosphonates, teriparatide, SERMs (raloxifene), calcitonin, denosumab

Question 2

osteopetrosis

Answer 2

• mut carbonic anhydrase –> lack of acidic envio –> defective osteoclasts –> failed bone resorption –> thickened, dense bones
• pancytopenia, extramedullary hematopoiesis, CN impingement, hydrocephalus

XR: symmetric sclerosis
tx: BM transplant (monocytes –> osteoclasts)

Question 3

osteomalacia/rickets

Answer 3

• defective mineralization of osteoid (osteomalacia)
• defective cartilaginous growth plates (rickets, children)
  labs: dec vit D –> dec serum Ca, normal PTH, inc ALP

XR: looser zones (pseudofractures), epiphyseal widening and metaphysical cupping, bow legs, rachitic rosary, craniotabes (soft skull)

tx: vit D and Ca

Question 4

Osteitis deformans

Answer 4

(Paget’s)

• localized disorder of bone remodeling
• inc osteoclastic activ followsd by inc osteoblastic activity –> poorly formed bone
• mosaic pattern of woven and lamellar bone
• long bone chalk stick fractures
• AV shunts –> high output HF
• inc risk osteosarcoma
• inc hat size, hearing loss
• OLDER pt, 70s

Stages: lytic (C), mixed (C, B), sclerotic (B), quiescent

labs: NML serum Ca, phosphorus, PTH. INC ALP

Question 5

avascular necrosis of bone

Answer 5

• infarction of bone and marrow, very painful
• usu at femoral head (watershed zone, insufficiency of medial circumflex femoral a.)
• via corticosteroids, alcoholism, sickle cell disease, trauma, SLE, the Bends, LEgg-Calve-Perthes disease (idiopathic), Gaucher disease, Slipped capital femoral epiphysis - CASTS Bend LEGS

Question 6

osteitis fibrosis cystica

Answer 6

• primary hypERthyroidism
• brown tumors (giant collection of osteoclasts)
• subperiosteal thinning
• idiopathic or parathyroid hyperplasia, adenoma, CA
  labs: dec serum Ca

Question 7

secondary hypERparathyroidism

Answer 7

• often as compensation for CKD (dec PO4 excretion and dec prod of activ vit D)
  labs: dec serum Ca

Question 8

osteochondroma

Answer 8

location: metaphysis of long bones
- lateral bony projection of growth plate (continuous w/ marrow space)
- RARELY –> chondrosarcoma
- most comm BENIGN bone tumor
- males < 25

Question 9

osteoma

Answer 9

location: surface of facial bones
- BENIGN
- associated with Gardner syndrome (FAP)
- middle aged

Question 10

osteoid osteoma

Answer 10

location: cortex of long bones, diaphysis region.
- BENIGN tumor of osteoblasts surr by rim of reactive bone
- bone pain worse at NIGHT
- relief w/ NSAIDs
- bony mass (<2cm) with radiolucent osteoid core

Question 11

osteoblastoma

Answer 11

location: vertebrae
- BENIGN, similar histo to osteoid osteoma but LARGER, and NON-responsive to NSAIDs
- M>F

Question 12

chondroma

Answer 12

location: medulla of small bones of hands/feet
- BENIGN tumor of cartilage
- may erode but doesn’t invade cortex

Question 13

giant cell tumor

Answer 13

location: epiphysis of long bones (knee region)
- locally aggressive benign tumor, neoplastic mononuclear cells that express RANKL and reactive multinucleate giant cells (OSTEOCLASTOMA)
- soap-bubble” on XR
- 20-40 y/o

Question 14

osteosarcoma

Answer 14

location: metaphysis of long bones (often knee)
- pleomorphic osteoid-producing cells (malignant osteoblasts)
- AGRESSIVE, MALIG
- presents as painful enlarging mass/soft-tissue swelling
- 20% of all primary bone cancers
- peak incidence of primary tumor in males <20yr
- XR: codman triangle, sunburst

• primary: responsible to surg/chemo
• secondary: poor prog (sec via Paget, bone infarcts, radiation, familial retinoblastoma, Li-fraumeni syndrome)

Question 15

chondrosarcoma

Answer 15

location: medulla of pelvis, proximal femur and humerus (CENTRAL)
- MALIGNANT chondrocytes, small calcific
- NO osteiod/bone prod

Question 16

benign tumors of cartilage are located

Answer 16

small bones of hands/feet

Question 17

malignant tumors of cartilage are located

Answer 17

location: centrally (pelvis, proximal femur/humerus)

Question 18

Ewing sarcoma

Answer 18

location: diaphysis of long bones (esp femur), pelvic flat bones-anaplastic small blue cells of neuroectodermal origin
- resemble LYMPHOCYTES, w/ patches of necrosis/hemorrhage
- t(11;22)
- “onion skin” periosteal rxn in bone
- caucasians, boys <15 y/o

-AGGRESSIVE w/ early mets, but responsive to chemo