Path Flashcards
appositional vs interstitial growth of cartilage
new cartilage formation at surface just beneath perichondrium vs lacunae chondrocytes to chondroblasts to make new internal cartilage
perichondrium
layer of dense connective tissue surrounding cartilage; has reserve chondroblasts deep to perichondrium
what distinguishes the types of cartilage?
all have ground substance consisting of chondroitin sulfate but differ by fiber type
hyaline vs fibro vs articular cartilage
most abundant and hardest cartilage d/t few collagen fibers; in articular, tracheal, costal, thyroid cartilage; matrix only visible w/ e- microscopy vs more pliable than hyaline b/c more collagen fibers –> tensile strength; in intervertebral discs, pubic symphysis, knee meniscus; matrix visible w/ light microscopy vs most pliable d/t collagen fibers + elastic fibers –> can recoil back to position –> form and flexibility; in ear (external and eustachian tube), epiglottis, larynx
how are lacunae connected?
by canaliculi –> cn give nutrients to osteocytes residing in there
interstitial lamellae
lamellae that don’t have their own Haversian system d/t remodeling –> 1st/2nd/3rd generation Haversian systems
osteoprogenitor cells vs blasts vs cytes vs clasts
undifferentiated fibroblast-like cells that give rise to blasts vs make glycoproteins and mucopolysacch to make uncalcified ground substance at external surface => osteoid vs formed when blasts = surrounded by matrix –> encased in lacunae vs large multinucleated phagocytic cells that digest bone matrix along internal surface for remodeling; found in Howship’s lacunae in compact bone
know what bone consists of
ECM: organic osteoid (type I collagen, proteoglycan, glycoprotein) –> tensile strength, inorganic hydroxyapatite (Ca2+, PO43-) –> rigidity
Cells: stem/blasts/cytes/clasts
bone contains internal (endosteum) and external (periosteum) lining of simple sq epithelia plus…?
underlying dense irreg connective tissue; and Sharpey’s fibers (attach bone to periosteum)
intramembranous vs endochondral ossification
bone formed from mesenchymal tissue w/o cartilage model –> highly vasc –> rapid cell prolif –> osteoprogenitor become blasts –> osteoid; flat bones vs bone formed from hyaline cartilage model –> cartilage cells prolif and hypertrophy –> lacunae inc in size –> calcified by lime salts –> cells below perichondrium differentiate to progenitor to blasts –> periosteal buds infiltrate enlarged lacunae => marrow space –> lime salts replaced by hydroxyapatite; happens in primary oss center in diaphysis first, then secondary oss center in epiphysis after; cartilage remains b/w dia and epiphysis => epiphyseal plate –> epiphyseal line –> longitudinal growth stops; long & short bones
appositional vs longitudinal growth of bone
inc diameter via intramembranous oss on external surface and clast activity on internal surface vs Reserve cartilage zone: resting chondrocytes ready to build bone
Zone of prolif: dividing chondrocytes in lacunae secrete bone and collagen
Zone of hypertrophy: maturing chondrocytes
Zone of cartilage calcification
Zone of provisional ossification
synovial joints
fibrous capsule w/ synovial fluid and cartilaginous articular surfaces
intervertebral discs: annulus fibrosis vs nucleus pulposis
outer fibrocartilage layer w/ collagen fibers in 90 degree planes vs gel like material from notochord –> partially displaced by fibrocartilage in adults
ex of dense regular connective tissue
tendons and ligaments
tendon vs ligament
muscle to bone; all collagen fibers run parallel; fibroblasts arranged in rows and flattened b/w thick collagen fibers; minimum vasc –> slow to heal; lubricated in tough fibrous sheet to minimize friction vs bone to bone; collagen + elastic fibers run parallel; irreg arrangement of fibroblasts
red/aerobic vs white/anaerobic fibers
small w/ rich mgb and blood supply –> slow twitch ctx and resistant to fatigue, darker ATPase, for maintenance and posture vs large w/ little mgb and blood supply –> fast twitch ctx and easily fatigued, lighter ATPase, for brief exertion of force
muscle spindles vs Golgi tendon
both = proprioceptors. senses muscle length and rate of change in muscle length –> prevent hyperelongation of muscle and tissue dmg; intrafusal muscle fibers enclosed in sheaths running parallel to extrafusal muscle fibers vs senses tendon tension and rate change of tension –> prevent excess tension in muscle and tissue dmg
can skel vs smooth muscle cells regenerate?
very limited –> replace by fibrous connective tissue scar or hypertrophy vs yes
Epimysium vs Perimysium vs Endomysium
surrounds entire muscle (ie. group of fasicles); continuous w/ tendon vs surrounds fascicle vs surrounds muscle fibers
skel vs cardiac vs sm muscle characteristics
striated, polynucleated voluntary vs striated, mono/binucleated, involuntary vs not striated, mononucleated, involuntary
Multi unit vs unitary smooth muscle
Each smooth muscle cell = innervated –> precisely controlled by ANS vs some muscle cells = innervated —> communicate via gap jxns –> synchronized ctx
achondroplasia vs thanatophoric dysplasia
both short stature and limb shortening, auto dom (homo dom = lethal). nml trunk, psychomotor nml; gain of fxn mutation in transmembrane domain of FGFR3 gene vs thoracic hypoplasia –> resp insufficiency –> lethal; gain of fxn mutation in intra/extracellular domain of FGFR3 gene
osteopetrosis
failure of clast activity –> no bone resorption –> inc bone density on XR, impaired bone re/modeling, abnlly shaped bones
3 types of osteopetrosis: infantile malignant vs intermediate vs adult/benign
most severe; Mutation in TCIRG1 gene; Inc in bone density –> weakens bone –> fx and osteomyelitis; no bone marrow development –> dec hematopoiesis –> dec leuks, RBC, PLT –> enlarged liver and spleen to compensate –> recurrent resp infxns vs Mutation in CLCN7 gene; auto rec; same pres as infant x/ moderate bone marrow vs Mutation in CLCN7 gene, auto dom; same pres as infant x/ nml bone marrow
imging of ostepetrosis
wide metaphysis –> erlenmyer flask deformity, no distinction b/w cortex and medulla
osteogenesis imperfecta
hypomineralization of skel and propensity to fx w/ minimal trauma; d/t mutation in COL1A1/2 for alpha1/2 in type I collagen; auto dom
type I vs II vs III vs IV collagen
Bone, dentin, ligament, sclera, skin vs hyaline cartilage vs Stroma of internal organs: liver, kidney, LN, blood vessels, intestines, ut vs basement membrane
collagen synthesis
Fibroblasts and osteoblasts make procollagen –> 2 α1 chains and 1 α2 chain make triple helix in Golgi –> tropocollagen –> collagen fibrils; need vit C for hydroxylation of pro/lys to make helix
4 types of OI: I vs II vs III vs IV
fx, blue sclerae for all. most common and mildest; nml stature, no bone deformity vs most severe; short vs most severe if survive neonatal; short, mod to severe bone deformity, hearing loss vs moderate; short, bone deformity, hearing loss
Marfan syndrome
multisystem d/o of connective tissue –> changes in skel, eyes, cardiovascular system; missense mutation in FBN1 gene (double neg mechanism) –> can’t make microfibrils or elastin in bone, eyes, heart/aorta
how to dx Marfan?
Ghent criteria; Major involvement of 2 of 4 organ systems (skel, eye, cardiovasc, skin) w/ minor involvement of another organ
Ehlers-Danlos Syndrome
13 heritable connective tissue d/o of joint hypermobility, skin hyperextensibility, tissue fragility; Mutation in TNXB gene, PLOD1 gene, ADAMTS2 gene
EDS: joint hypermobility vs skin hyperextensibility vs tissue fragility
can move joint beyond ROM –> luxation, sprains vs stretch skin for 4cm till feeling resistance and snaps back after release; fragile can split easily –> “cig paper scars” vs easy bruising/ecchymosis, hematoma
3 types of EDS: classic vs hypermobility vs vascular
mutation in COL5A1/2 gene –> triad of joint hypermobility, skin hyperextensibility, easy bruising; auto dom vs joint hypermobility, mild skin hyperextensibility vs mutation in COL3A1 gene –> rupture of blood vessels; auto dom
Paget’s
Inactivating mutation in SQSTM1 gene –> inc osteoclastogenesis –> inc clasts –> inc sRANKL –> bone resorption –> enlarged, deformed, densely sclerotic brittle bone; mono or polyostotic, doesn’t spread from bone to bone
3 phases of Pagets: Osteolytic vs mixed clast-blast vs final phase/burned out PDB
Predominant clast activity, 9 nuclei in giant multinucleated clasts (nmlly they have 3) vs predominant blast activity –> lamellar bone laid down unorganized –> mosaic pattern –> thick trabeculae –> encroach bone marrow cavity; clasts persist vs Bone resorption and formation slow and stop –> enlarged, deformed, densely sclerotic brittle bone
clinical pres of Pagets
asx; localized bone pain d/t bone overgrowth, fx, nerve compression, secondary osteoarthritis; skull enlargement, kyphosis, bowing
how to tx Pagets?
bisphosphonates –> dec bone resorption –> clast apop
labs for Pagets
o Inc serumALP –> bone formation
o Inc procollagen I N-terminal propeptide (PINP), serum C-telopeptide (CTx), urinary N-telopeptide (NTx), urinary hydroxyproline –> bone resorption
o Nml serum calcium and phosphate
Metaphyseal Fibrous Defect
prolif of benign fibrous tissue involving metaphysis of long bones (femur, tibia, knee) in children; Granular, red-brown area of bone w/ rubbery consistency
how to tx Metaphyseal Fibrous Defect?
curettage and bone grafting
fibrous dysplasia
mutation in GNAS1 gene –> inc cAMP –> mutated blasts –> differentiate to immature fibroblasts –> produce spicules of woven bone meshed in dysplastic fibrous tissue (looks like Chinese characters)
fibrous dysplasia = somatic mosaic dz, meaning?
Mutation occurs after fert in somatic cells –> all cells derived from mutated cells have dysplastic features
imging of fibrous dysplasia
Radiolucent lesion w/ “ground glass” pattern
Syndromic forms of fibrous dysplasia: Mazabraud Syndrome vs McCune-Albright Syndrome
benign d/o of soft tissue myxomas w/ fibrous dysplasia vs Post-zygotic, sporadic, somatic mutation of GNAS1 gene –> inc Gs –> polyostotic fibrous dysplasia, melanin prod/cafe au lait spots, estrogen prod/precocious puberty
osteoporosis
metabolic bone dz w/ low bone mass, microarchitectural disruption and skeletal fragility –> dec bone strength and inc risk of fx
primary osteoporosis: type I vs type II
Cancellous > cortical bone loss at menopause b/c no estrogen; Estrogen promotes antipop blast and proapop clast vs Cortical bone loss b/c dec bone stem cell precursor –> dec blast –> dec bone formation
secondary osteoporosis: hypogonadism vs hyperthyroid vs Immobilization/Disuse osteoporosis vs meds
No testosterone, estrogen, or androgen receptors in blasts –> accelerated bone loss vs Excess thyroid hormone –> accelerated bone resorption vs eh vs long term corticosteroids, anticoag like heparin (inc resorption, dec formation), anticonvulsant
juvenile idiopathic osteoporosis
Primary bone demineralization b/c low bone formation
clinical pres of osteoporosis
o Back pain, chronic dull back ache
o Loss of height, kyphosis; unsure of gait
labs of osteoporosis
Ca2+, PO43-, and ALP nml in primary osteoporosis; Likely not nml in secondary osteoporosis
imging for osteoporosis
verticalization (Non-weight bearing/horizontal trabeculae = resorbed first –> prominent weight bearing/vertical trabeculae), pic frame (Trabecular bone = radiolucent –> vertebrae has “picture frame” appearance), cortical thinning
osteonecrosis
bone death d/t compromised blood flow in bone and bone marrow; multifactorial
traumatic vs nontraumatic osteonecrosis
fx –> disruption of arteries vs glucocorticoids, immunosuppressants, alc
clinical pres for osteonecrosis
o Pain in groin, thigh, buttock, walking
o Reduced ROM in hip joint
o Crepitus
imging for osteonecrosis
CT or MRI showing avasc necrosis
osteoarthritis/DJD
genetic chronic dz of synovial joints from breakdown of articular cartilage –> lose hyaline cartilage; most common form of arthritis
risk factors of osteoarthritis
o inc w/ age, more in women and athletes, obesity
o radiologic OA > symptomatic OA
o osteoporosis, previous joint injuries
3 stages of OA
o Stage 1: absolute or relative overload of cartilage matrix –> IL-1 and TNFα communicate in auto/paracrine fashion in cartilage –> activate matrix-degrading enzymes
o Stage 2: fibrillation and erosion of cartilage –> release proteoglycan and collagen into synovial fluid
o Stage 3: breakdown products of cartilage activate inflamm response in synovial membrane –> irreversible loss of cartilage –> compensatory bone overgrowth to stabilize joint
what is nml cartilage like? superficial vs middle vs deep zone vs tidemark vs Calcified cartilage ?
Articular surfaces at synovial joints = lined by hyaline cartilage (type II collagen + water). collagen and flat chondrocytes parallel to surface vs collagen and chondrocytes in random orientation vs collagen and chondrocytes perpendicular to surface vs boundary layer b/w uncalcified and calcified cartilage vs chondrocytes and calcium apatite crystals; intermediate b/w cartilage and bone
clinical pres of OA
o Pain, morning stiffness, reduced ROM, joint effusions, gross joint deformities
o Crepitus
o Tenderness to palpation
o Osteophytes
o Muscle atrophy
types of OA: primary vs secondary
Age, women
Localized
Bouchard nodes at PIP, Heberden nodes at DIP vs Genetic, obesity
Monoarticular or polyarticular
labs for OA
o ESR, blood count, UA nml
o Synovial fluid nml (If inflamed: cloudy, translucent, less viscous w/ high leuks)
imging for OA
o Intraarticular loose bodies (free bone or cartilage frag in synovial fluid)
o Joint space narrowing, change in contouring of joint
o Subchondral sclerosis, subchondral cyst
o Osteophytes
neuropathic arthropathy
progressive joint destruction d/t disturbance in joint innervation; Caused by DM (tarsal bones), syphilis (hip, knee), syringomyelia (shoulder, elbow)
clinical pres for neuropathic arthropathy
o No pain
o Swollen, warm, erythematous joint; joint instability or dislocation
imging for neuropathic arthropathy
o Pencil-cup deformity (Bone resorption, Destruction of articular surface, Subchondral sclerosis)
gout
Endogenous (from D/RNA) purine degradation → deaminated to hypoxanthine and xanthine → xanthine oxidase converts to uric acid → overprod (10% of gout) or underexcretion (90% of gout) of uric acid → high serum and urine uric acid conc => hyperuricemia and hyperuricosuria → MSU crystals in joints
which organs elim uric acid?
o Kidney elim 2/3, GI tract elim 1/3 of uric acid
primary uricemia = caused by?
HPRT defic
* Caused by X-linked mutation in HPRT1 gene encoding HPRT that converts purines back into nucleotides in salvage pathway
o Mutation –> excess purines –> uric acid –> MSU
primary uricemia: Lesch-Myhan syndrome vs Kelley-Seegmiller syndrome vs Phosphoribosyl pyrophosphate synthetase superactivity
overprod of uric acid, o Psychomotor delay, cognitive disturbances, self-injuring behavior vs gouty arthritis vs o Gain of fxn mutation in PRSP gene encoding PRS enzyme that makes phosphoribosyl pyrophosphate; Mutation –> excess purines –> uric acid –> MSU; early onset severe form = gout, urolithiasis, neurodevelopmental anomalies, or late onset mild form = gouty arthritis
risk factors of gout
age, men, immunosuppressants and alc inc uric acid, obesity, purine rich foods (red, organ meats)
4 stages of gout
Stage 1: Asx hyperuricemia
Stage 2: monoarticular acute gouty arthritis; Can be resolved spont after days to weeks; Inflamm response: MSU crystals = phag by macs and synovial lining cells –> activate inflammasome in synovial macs –> activate caspase-1 –> IL-1β –> neu influx into synovium –> resp burst and cytokine release –> Use IL-1β antagonists to tx gout flares
Stage 3: Intercritical gout; Asx b/w attacks of gouty arthritis but ongoing deposition of uric acid crystals
Stage 4: Chronic tophaceous gout; Polyarticular gouty arthritis and tophi (deposit of MSU crystals w/ longstanding hyperuricemia; painless)
labs for gout
joint aspiration –> neutrophilic leukocytosis, high ESR (nonspecific), intracellular MSU in synovial fluid via polarized light microscopy; needle shaped, strongly negative birefringent crystals
imging for gout
“punched out” extraarticular erosions w/ overhanging edge
Calcium pyrophosphate dihydrate deposition dz
metabolic joint dz from deposition of CPPD crystals in joints, esp articular hyaline and fibrocartilage
familial vs secondary CPPD
Gain of fxn mutation in ANKH gene encoding transmembrane protein transporting PPi out of cells to ECM; Mutation –> more PPi in ECM –> CPPD crystals in joints; Auto dom vs From hypophosphatasia, hypomagnesemia, hyper/hypoparathyroidism, hemochromatosis
inflamm response of CPPD
CPP crystals = phag by synovial macs –> activate inflammasome –> activate caspase-1 –> IL-1β –> neu influx into synovium –> resp burst and cytokine release
clinical pres of CPPD
Asx; Similar to osteoarthritis, acute gouty arthritis, RA, neuropathic arthropathy
labs for CPPD
Synovial fluid analysis shows CPPD crystals –> Rhomboid-shaped, weakly positively birefringent crystals; harder to detect than MSU crystals b/c polymorphic
imging for CPPD
o Radiopaque
o Deposited in hyaline or fibrocartilage
o Thin, dense, linear calcifications parallel to articular surface separate from underlying subchondral bone
Basic calcium phosphate deposition dz
basic calcium phosphate crystals in periarticular soft tissue
Basic calcium phosphate deposition dz: Acute calcific periarthritis vs Milwaukee shoulder syndrome
Asx;
o Severe shoulder pain, swelling, warmth, erythema
o Women 30-50yo
vs
o Rapidly progressive and destructive shoulder arthritis
o Severe shoulder pain, swelling, limited ROM
o Women >70yo
toxic myopathies: Statin-induced vs Glucocorticoid-induced vs Chloroquine-induced vs alc-induced
muscle pain, muscle weakness, rhabdomyolysis, inc serum kinase –> muscle bx shows necrosis, phag, regeneration vs muscle protein catab in type II fibers –> muscle bx shows atrophy of type II fibers vs Inhibit lysosomal fxn and autophagy in type I fibers –> autophagic vacuoles on light microscopy –> muscle weakness vs o Alc and acetaldehyde = inhibitors of muscle protein synthesis –> acute (muscle weakness, necrosis, inc serum creatine kinase and mgb) or chronic (atrophy of type II fibers)
Dystrophinopathies
X linked rec d/o caused by mutation in DMD gene on Xp21 encoding dystrophin; no dystrophin –> Ca2+ flows in b/c inflamm mediators of dystrophic muscle inc nitric oxide synthase –> destabilize ryanodine receptors of SR –> excess Ca2+ enters –> muscle fiber necrosis –> replaced by adipose and fibrotic connective tissue –> muscle weakness
clinical pres of Dystrophinopathies
Weakness in proximal and LE first then spreads up and out
Becker muscular dystrophy vs Duchenne muscular dystrophy
mild; Dystrophin lvls = 30-80% of nml
Wheelchair by 16yo
Hypercontracted fibers (intensely stained red H&E fibers)
Dystrophin immunochemistry confirms irreg, reduced, discontinuous dystrophin
Moderate inc in serum CK
vs severe; Dystrophin lvls = 5% of nml
Mild cognitive impairment, delay in development of gross motor skills –> wheelchair by 12yo
Hypercontracted fibers (intensely stained red H&E fibers)
Dystrophin immunochemistry confirms complete absence of dystrophin
Severe inc in serum CK
Incomplete muscle repair –> muscle fiber necrosis/myonecrosis –> fibrosis from collagen fibers and adipose –> stiffness and contractures –> weakness
Dilated cardiomyopathy, conduction abnormalities, resp insufficiency –> all lead to death
myotonic dystrophy: DM1 vs DM2
Gain of fxn mRNA mutation where hundreds to thousands of CTG trinucleotide rpt in DMPK gene –> DMPK mRNA transcript binds and sequesters musclebind-like splicing regulator 1 (MBL1) –> disrupts nml splicing –> abnl splicing of transcript for chloride channel CLC1 –> CLC1 can’t perform nml muscle ctx –> myotonia vs o Gain of fxn mRNA mutation where hundreds to thousands of CCTG tetranucleotide rpt in ZNF9 gene encoding RNA-binding protein
Emery-Dreifuss muscular dystrophy
X-linked mutation in EMD gene encoding emerin, X-linked mutation in FHL1 gene encoding 4.5 LIM domains-1 protein, auto dom > rec mutation in LMNA gene encoding lamin A & C –> Triad of joint contractures, progressive muscle weakness and wasting from humero-peroneal distribution to scapular and pelvic girdle muscles, dilated cardiomyopathy
Fascioscapulohumeral muscular dystrophy
Gain of fxn mutation of DUX4 gene –> reduction of satellite rpt array –> disrupts methylation –> chromatin relaxation –> inc DUX4 transcpxn; Progressive muscle weakness of face –> shoulder –> arms –> abd, foot
Limb-girdle muscular dystrophy
auto rec > dom mutation in CAPN3 gene encoding calpain-3 for regulating sarcomere formation and remodeling –> Shoulder and pelvic girdle atrophy
Congenital Myopathies: central core dz vs nemaline atrophy vs centronuclear myopathy vs Congenital fiber type disproportion
auto dom Mutation in RYR1 gene –> cores in muscle cells = present but oxidative activity absent vs auto rec Mutation in NEB gene encoding nebulin –> small rod-like inclusions in muscle fibers vs X-linked Mutation in myotubularin (MTM1) gene –> abnlly large, vesicular, central nuclei vs o auto dom or rec mutation in TPM3 gene –> smaller type I fibers than type II
Ion channel myopathies: Hyperkalemic periodic paralysis (hyperPP) vs Hypokalemia periodic paralysis (hypoPP)
Mutation in SCN4A gene encoding for sodium channel –> depolarization vs Mutation in CACNA1S gene for calcium channel –> excitation-initiation ctx; low potassium = trigger
osteomalacia
dec mineralization of newly formed osteoid in adults d/t vit D deficiency
where to get D2 vs D3?
- D2 = ergocalciferol, in food
- UV –> 7-hydrocholesterol –> D3 = cholecalciferol
how are D2/3 hydroxylated?
Hydroxylation of D2/3 via 25-hydroxylase in hepatocytes –> 25-hydroxycholecacliferol = calcidiol –> hydroxylation via 1α-hydroxylase –> active form of vit D = 1,25-(OH)2D = calcitriol
how are D2/3 inactivated?
24-hydroxylase (CYP4A1) –> 24,25-dihydrocholecalicferol = calcitroic acid
Low Ca2+ levels vs High Ca2+ levels
PTH inc –> calcitriol –> clast resorption –> Ca2+ and PO43- released in blood
intestinal absorption of Ca2+ and PO43-
Ca2+ and PO43- reabsorption in proximal tubules
stimulate blasts to make calcium-binding protein osteocalcin for bone development
vs
o PTH dec no calcitriol
o Thyroid secretes calcitonin inhibit clast activity and excrete Ca2+ and PO43-
3 stages of osteomalacia
o Stage I: calcidiol dec –> dec resorption and inc Ca2+ absorption –> hypocalcemia
o Stage II: hypocalcemia –> inc PTH (secondary hyperparathyroidism) –> inc clast activity; Inc plasma ALP; Dec plasma phosphate
o Stage III: secondary hyperparathyroidism can’t keep up –> hypocalcemia and hypophosphatemia
clinical pres of osteomalacia
o Asx
o Diffuse bone pain, proximal muscle weakness/myopathy –> difficulty walking and getting up
o Bone fx w/ little trauma
o Bowing deformity of long bones in LE
o Neuromuscular irritability
labs for osteomalacia and rickets
o Dec calcidiol, phosphate
o Inc PTH, calcitriol, ALP
o Low Ca2+ in stage I, nml in stage II, low in stage III
img for osteomalacia
o Large and biconvex vertebral discs
o Looser zones representing incomplete fx
o Coxa profunda hip deformity: Hip socket = too deep –> severe pain
how to dx osteomalacia?
o Bone bx
Give 2 courses of tetracycline 10d apart prior to full thickness undecalcified bone bx
Tetracycline analysis w/ fluorescent microscopy
o Nml: separate fluorescent bands = 1 um for qd b/w courses of tetracycline
o Osteomalacia: no fluorescent line, or maybe single or double bands
rickets
dec mineralization of cartilage in epiphyseal growth plates in children d/t vit D or phosphate deficiency
how do kids get vit D vs phosphate defic?
o From prolonged breastfeeding + no sun exposure or vit D supplementation vs
o Renal phosphate wasting
o Hereditary
clinical pres of rickets
skull deformities (craniotabes, frontal bossing, delayed suture fusion of anterior fontanelles), dental deformities, limb deformities (genu valgus/varus), chest deformities, muscle weakness
imging for rickets
o Widening and disorganization of epiphyseal growth plate w/ cupping and fraying
o Long bone shafts = osteopenic
o Thin cortices
o Looser zones, greenstick fx
Osteitis fibrosa cystica
metabolic bone dz d/t hyperparathyroidism (autonomous overprod of PTH)
what happens if you inc PTH?
o Inc clast activity –> bone resorption –> inc serum Ca2+ –> inc renal tubular reabsorption of Ca2+ and dec reabsorption of PO43-
o Inc gastrointestinal Ca2+ absorption
o Inc 1α-hydroxylase –> inc calcidiol to calcitriol
o Stimulates both blasts and clasts –> bone formation and resorption
labs for OFC
o Inc PTH, serum Ca2+, 24hr urinary Ca2+, calcitriol, ALP
o Dec serum PO43-, calcidiol
imging for OFC
o Demineralization/diffuse osteopenia
o Thin cortices especially prox and middle phalanges of 2nd and 3rd fingers
o Salt and pepper sign
o Brown tumors w/ lytic lesions
Renal Osteodystrophy
metabolic bone dz d/t renal failure or end-stage renal dz; * Chronic renal dz –> dmged kidneys –> dec 1α-hydroxylase –> no calcidiol to calcitriol –> calcitriol defic –> dec intestinal absorption of Ca2+ –> hypocalcemia –> inc PTH –> secondary hyperparathyroidism
5 skel changes for ROD
o Inc clast bone resorption like osteitis fibrosa cystica
o Delayed mtrix mineralization like osteomalacia
o Bowing and softening of bones
o Inc bone mass like osteosclerosis
o Dec BMD via DEXA
clinical pres for ROD
o Adults show osteitis fibrosa cystica and osteomalacia
o Children show rickets and growth retardation
o Basilar invagination
labs for ROD
o Inc phosphate, PTH, ALP
o Dec calcium, calcidiol (can be nml), calcitriol
imging for ROD
o Alternating bands of opaque sclerotic bone and nml dense bone => rugger jersey spine
imging for Pagets
bone scintigraphy w/ technetium (pos when inc uptake of radionuclide)
imging for MFD
metaphysis protruding into medullary cavity
Marfan’s microfibrils in bones: in general vs Dolichocephaly vs Dolichostenomelia vs Arachnodactyly
Excessive linear growth of long bones and joint laxity –> taller vs long narrow skull vs disproportionately long limbs vs abnlly long and slender fingers
