Bone Pathology
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- Describe the radiographic, gross and micro changes in osteitis fibrosa cystica
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Radio:subperiosteal resorption especially on the radial side of the middle phalanges, salt and pepper skull
Gross: Brown Tumors due to microfracture/hemorrhage
Micro: Increased bone cell activity, peritrabecular fibrosis, brown tumors. - Characterize pathologic forms of renal osteodystrophy in terms of pathogenesis
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these are skeletal changes of chronic renal disease:
1. increased osteoclastic bone resorption
2. delayed matrix mineralization.
3. osteosclerosis
4. growth retardation
5. osteoporosis
Due to phosphate retention, 2ndary HyperPTH, Hypocalcemia, Metabolic Acidosis due to renal failure causes increase in calcium phosphate release. - Decribe the genetic basis for Achondroplasia and gross and micro appearance
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1. Autosomal Dominant FGF3 receptor defect
-Short limbs and frontal bossing with midface deficiency.
-thick bones - Describe the genetic basis for Thanatotropic dwarfism and the gross and micro changes
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Missense mutation in FGF3
-Severe limb shortening and bowing
-frontal bossing
-depressed nasal bridge -
Osteogenesis imperfecta:
1. Biochemical Basis
2. Classification
3. Physical Characteristics of Type 1 -
OI is caused by deficiencies in the synthesis of Type 1 collagen, specifically due to alpha 1,2 chains of collagen molecule.
-There are mild and severe phenotypes, which can have varying characteristics
Type 1: Blue Sclera, Hearing Loss, Dental Imperfections. - Characterize acute osteomyelitis in terms of most common organisms, routes of infection, gross and micro appearance
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Most common: #1 S.Aureus
Ecoli, Pseudomonas, klebsiella. Hinfluenza and group b strep are neonatal
-Usually Hematogenous spread
-Acute inflammatory rxn, cell death and necrosis w/48hrs. Abscess forms in kids, Sequestrum forms. Chronic inflammation stimulates bone resorption, and a sleeve of living tissue called an involucrum forms around it. - Characterize Tuberculosis osteomyelitis in terms of most common bones affected, synonym for dx of the spine, and natural hx
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-Most common locations: spine (pott dx), hips, knees, long bones, bones of hands and feet.
-Spine is most common site, followed by hips/knees. infection spreads through large areas of the medullary cavity to cause extensive necrosis. in spine it can form abscesses. - Describe the pathogenesis of rickets and osteomalacia, and their nutritional causes
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Rickets: caused by vitD deficiency in children. increased thickness of epiphyseal plates. craniotabes, late closing of fontanelles, rachitic rosary, harrison groove, pigeon breast, decreased height
-Osteomalacia:VitD deficiency in adults, defective calcification of osteoid matrix, looks like osteoporosis, when secondary to renal dx, its called renal osteodystrophy -
Describe the molecular basis for:
1. Familial benign Hypocalciuric Hypercalcemia
2. MEN1
3. MEN2
4. Vit D Resistant Rickets
5. Hypophosphatemia -
1. Autosomal Dominant, loss of function mutation so PTH receptor doesnt work properly = mild HyperPTH. Benign
2. Tumors are pituitary, Parathyroid, Pancreas, loss of function of tumor suppressor gene Menin
3. Activation mutations of RETPRO oncogene in parathyroid and parafollicular C cells of thyroid. 30%penetrance
4. PHEX gene which deactivats FGF23 is mutated, which then blocks D3 formation
5. Alkaline phosphatase gene is blocked, normally inhibits bone mineralization. - Discuss therapeutic indications, MOA, administration methods of calcitonin
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Calcitonin: Used to Tx Pagets, Osteoporosis
-Intranasally/IV
-Inhibits osteoclast activity, prevents calcium/phosphate loss from renal. - Discuss Clinical Use, MOA, adverse effects of bisphosphonates:
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-Tx Pagets, Osteoporosis
-Inhibits OH pump on osteoclasts, blocking hydroxyapetate dissolving
-apoptosis of osteoclasts, blocks osteoclast formation.
-Nausia, Diarrhea, abdominal pain. esophageal ulcers, Osteomalacia - Clin Use of Vit D3
- 125 dihydroxycholecalciferol is active form. increases intestinal absorption of calcium, also phosphate and mg ions.
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eval and tx:
1. hypercalcemia
2. hyperPTH
3. Hypocalcemia -
1. eval:moans,bones,groans, stones
tx:IV NS, Loop diuretic IV bisphosphonates, Calcitonin, IV glucocorticoids
2. EVAL: serum calcium, phosphate,alk phos levels, 24 urine ca/po4, dexa scan, ultrasound of renal system, PTH levels
Tx: Estrogen replacement, bisphosphonates,surgery,cinacalet
3. Tetany,Chvostek's,Trousseau's,siezures,ProlongedQT,Subcapsular cataracts,impetigo herpetiformis,pustular psoriasis
Tx: IV calcium, D3,PO calcium, VitD, Thiazide diuretic to block Ca loss -
Eval and Tx:
1. HypoPTH
2. Vit D deficiency
3. OI -
1. Eval:Carpal pedal syndrome, hyperphosphatemia,Low PTH with low Ca.
tx: IV calcium, emergency airway,diuretic, vit d preps,
2. Eval: apathetic, weak, poor child growth, soft head, wide sutures,frontal bossing, bowed limbs, fractures, low d3 levels
tx: Vit D, tx disorder
3. Skeletol deformities, Blue Sclera, deafness, skin/valvular abnormalities,
tx: orthopedic interventions, rehab, dental work, bisphosphonates.