Musculoskeletal System Pathology - Walby Flashcards
Osteoprogenitor cells are (toti/pluri)potent
pluripotent
T/F: osteoprogenitor cells are on all bony surfaces
true
Where are osteoblasts found?
surface of the bone
WHere are osteoclasts found?
granulocyte precursors of the marrow
What cell is in Howship’s lacunae?
osteoclasts
What bone cells communicate with each other via canaliculi?
osteocytes
what forms bone matrix?
osteoblast
what maintains bone tissue
osteocyte
The periosteum is made of what two layers?
outer fibrous
inner osteogenic
What type of collagen forms 90 % of the organic component of the bone?
Type I collagen
Woven bone is seen during what part of dev?
fetal skeleton and during repairs from breaks
What is the most common disease of the growth plate?
achondroplasia
what is the histology like in achondroplasia?
disorderly laydown of bone
Achondroplasia has a mutation in what receptor?
Fibroblast growth factor receptor 3 (FGFR3)
What is the most common form of Achondroplasia?
heterozygous auto dom
Describe the physical features of heterzygote Achondroplasia?
Infants have shortened extremities, bowing of legs, lordosis (sway-back), relatively normal trunks, and enlarged heads (spares the cranium & vertebrae), frontal bossing, saddle nose
T/F: growth hormone helps in the development of homozygous Achondroplasia
False
What other complications arise in homozygous Achondroplasia?
compromised respiratory function (abn chest cavity); die in infancy
What is the lifespan in Achondroplasia?
normal
What is a Lysosomal storage diseases involving acid hydrolases?
mucopoplysaccharidoses
How does mucopolysaccharidoses manifest physically?
Results in abnormalities of hyaline cartilage, and hence growth plates and articular surfaces, due to abnormalities of chondrocytes, and hence growth plates, articular cartilage, etc.
Manifest as chest wall deformities, short stature, and malformed bones
Osteogenesis imperfecta is a disease of (bone growth/matrix formation)
matrix formation
OI is also known as:
brittle bone disease
OI is caused by a abn. in what type of collagen
/
type 1
What disease has this presentation?
joints (lax), eyes (blue sclera), ears (deafness), skin (thin), and teeth (small & discolored)
What is unique about the eyes in OI?
the sclera is blue
Big picture wise, what is the issue in OI?
too little bone; cortical thinning and attenuation of trabecular bone–woven instead of lamellar
Which types of OI are most likely to survive?
types I and IV
What are the common features of survivors of OI?
hearing deficits
BLUE YELLOW TEETH
fractures
What type of OI is this?Perinatal demise (mostly Auto Rec)
II
What type of OI is this?
Postnatal fractures without blue sclerae (Auto Dom)
IV
What type of OI is this?
Postnatal fractures with blue sclerae, deafness (Auto Dom)
I
What type of OI is this?
Progressively deforming w/ growth retardation (Auto Rec)
III
Vitamin D deficiency resulting in rickets results in decreased (blank) and an increase in (blank)
decrease in mineralization and an increase in osteoid
HyperPTH has what effect on bone?
decreased bone density
Osteoporosis has a decreased bone (blank)
density and mass
T/F: there is a abn. in the ratio of minerals in the bone in osteoporosis
false
What causes localized/focal osteoporosis?
disuse
Primary osteoporosis is seen in what age group and sexes?
post menopausal women and senile in old men
People from what countries are at risk of developing osteoporosis?
N. european and Asians
T/F: Hispanics have a lower risk of osteoporosis compared to europeans
false; similar
What race is at the least risk of developing osteoporosis?
african americans
excessive consumption of what things can lead to osteoporosis?
EtOH caffeine carbonated beverages smoking ciggies anticonvulsants or benzos long term
What hormonal imbalances can lead to osteoporosis?
Hypogonadism resulting in reducted testosterone
Hypercortisol states
HyperPTH
Inadequate Ca2+ or Vit. D in diet
Plain XRAY doesn’t see osteoporosis until what percent of bone is gone?
30-40%
T/F: serum calcium and phosphorus are not diagnostic for osteoporosis
true
T/F: there is no sensitive or specific test for osteoporosis
true
Kyphoscoliosis and lordosis are complications of osteoporosis that arise as a result of fractures in what regions of the spine?
thoracic and lumbar
T/F: osteoporosis also shows up as fractrues in the wrist
true
Fractures of the femoral neck, pelvis, and spine are complicated by (blank) and pneumonia
PE
What is the characteristic appearance of osteoporotic vertebrae?
fish mouth appearance
when do we reach our peak bone mass?
3rd decade
Where do we lose the most bone mass?
spine and femoral head
low calcium intake in what age group and sex predisposes for osteoporosis?
adolescent girls
Where is most of the bone resorption coming from in osteoporosis?
cancellous bone
what percent of women will have an osteoporotic bone fracture in their life?
1/2
How does decreased estrogen lead to increased bone resorption?
increased IL1
increased IL6
recruits osteoclasts and increases bone resorption
what is the most potent activator of osteoclasts?
IL1
Paget’s diseases is caused by (blank) dysfunction
osteoclast
What are the three stages of osteoclast dysfunction?
- otesoclast/osteolytic stage–hypervascularity and bone loss
- mixed stage with osteoblastic activity
- burnt-out osteosclerotic stage
When does Paget’s onset?
5th decade
What is the racial predilection of Paget’s?
whites of N. europe and US
What countries is Pagets rare in?
Scandinavia, China, Japan, and Afrika
What is the histological change in the osteoclasts in Pagets?
become multinucleate
In Pagets, the marrow is replaced by (blank)
CT containing osteoprogenitor cells and blood vessels
The characteristic histological finding of Pagets is a (blank) pattern, making bone look like a jigsaw
mosaic pattern
T/F: even though the bone is denser it is weaker in Pagets
true
what virus can cause Pagets?
paramyxovirus causing MEASLES
explain how a virus can induce Pagets?
virus induces IL6 which activates osteoclasts and blasts are then in reponse to the clasts
90% of Pagets are (poly/.mono) ostic
polyostotic including pelvis, spine, and skull
THe axial skeleton and proximal femur are involved in what percent of pagets?
80%
What bones are rarely affected by Pagets?
ribs, fibula, small bones of hands and feet
t/F: most cases of Pagets are asymptomatic and found only by chance
true
What are the early symtpoms of Pagets?
headache, hearing loss, visual changes, pain is the most common problem
What is the cause of pain and HA in Pagets?
microfractures and bone overgrowth which compresses spinal and cranial nerve roots
What is the name for the Paget facies?
leonine facies; difficult to stand upright due to wt. of the bone
Severe secondary osteoarthritis arises in Pagets due to what>
severe bowing of the long bones from the weight
The increase in blood flow in severe polyostotic Pagets causes a (blank), resulting in high output cardiac failure
functional arterio-venous shunt
What is the characteristic finding of Pagets on XRAY?
cotton wool spots
Giant cell tumors, sarcomas, and extramedullary hematopoiesis are complications of what dz?
Pagets
T/F: giant cell tumors are benign
true
WHat are the lab values that are abn in pagets?
inc. serum Alk phos
inc. urinary hydroxyproline
NORMAL serum calcium and phosphate
WHat is the Tx for Pagets?
anti-resorptive agents like biphosphonates and calcitoniin
T/F: osteopetrosis makes brittle bones
true
Osteopetrosis is too much (mineral/osteoid)
mineral
What can cause osteosclerosis?
osteopetrosis
A variant of osteopetrosis is caused by a def. in what enzyme necessary for excretoin of Hydrogen ions to acidify the environment to resorb matrix?
carbonic anhydrase II
What are the labs for osteomalacia/rickets? Calcium Phosphate ALK PHOS PTH
Calcium dec.
Phosphate dec.
ALK PHOS inc.
PTH inc.
What are the labs for osteopetrosis? Calcium Phosphate ALK PHOS PTH
Calcium normal
Phosphate normal
ALK PHOS inc.
PTH normal
What are the labs for osteoporosis? Calcium Phosphate ALK PHOS PTH
Calcium normal
Phosphate normal
ALK PHOS normal
PTH normal
What are the labs for Pagets? Calcium Phosphate ALK PHOS PTH
Calcium normal
Phosphate normal
ALK PHOS variable
PTH normal
What disease presents with brown tumors in the bone?
osteitis fibrosa cystica
vitamin d def leads to an increase in what substance in the bone?
osteoid
what is the vitamin d precursor from plants?>
ergosterol
what is vitamin d bound to on its way to the liver?
a-1-globulin d binding protein
In the (blank) vitamin d is converted to 25-OH vit d and in the (blank) it is then converted to 1,25OH-D, which is the active form
liver then kidney
elevated 1,25 OHD inhibits (blank)
alpha hydroxylase
hypocalcemia stimulates what hormone?
PTH, which activates alpha hydroxylase
Hypophosphatemia directly activates (blank) to increase 1,25 OH D
alpha hydroxylase
Vit D required for normal mineralizatoin of epiphyseal cartilage and (blank) matrix
osteoid
Overall, vit. d. def results in (blank) def
Calcium
What drugs break down vitamin D?
phenytoin, phenobarbitol, rifampin, CYP450
What is the mechanism of deformation in rickets?
overgrowth of epiphyseal cartilage
In rickets, there is an enlargement and lateral expansion of the (blank) junction
osetochondral junction
Why do you get a growth of capillaries and fibroblasts in the disorganized zones of rickets?
microfractures bring them in
an excess of osteoid in rickets produces (blank) and a squared appearance to the head
frontal bossing
Rachitic rosary is overgrowth of cartilage at the costochondral junction where?
in the chest
Pidgeon breast in rickets is due to what?
respiratory muscles pulling on the weak metaphyseal areas of the ribs
What is Harrison’s groove?
girdling of thoracic cavity at lower margin of rib cage due to pull of diaphragm
lumbar lordosis and bowing of the legs is seen in ….
rickets
Are the contours of the bone affected in osteomalacia?
no
osteomalacia has an excess of what?
osteoid; too much and too weak
Which bones are most affected by osteomalacia?
vertebra and femoral neck
increased PTH levels leads to increased osteo(clast/blast) activity
clast
