Bone Pathology - Witrak Flashcards by Jesse Cobell

What is the leading cause of bone fractures in our country?

Osteoporosis

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What is osteopenia

Diffusely demineralized bone, can see on x-rays

Could be caused by:
Osteoporosis (usually the case)
Osteomalacia
Malignancy
Rare hereditary disorder (aka osteogenesis imperfecta)

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What is the most common type of tumor you see in the skeleton?

metastatic tumors from other sites

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What is a pathological fracture?

fracture through diseased bone (most often through tumorous bone)

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Which bone cells secrete alkaline phosphatase?

Osteoblasts

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What is sacrificed in the body in order to maintain ionized calcium at the right levels

Itegrity of the skeleton

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Source of Vitamin D?

Sunshine in skin

what you ingest

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What is required in order to have healthy bones?

In summary, for healthy bone:

Ca, P (from diet)
Vit D (from diet, skin synthesis)
gut (absorbing Ca, P, Vit D)
healthy kidney (makes Vit D (OH)2, resorbs/excretes Ca, P)
parathyroids (master gland for Ca, bone metabolism)

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What is a salter fracture?

Epiphyseal plate injury that could lead to growth disturbance

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What is fat embolism syndrome?

Usually occurs in people who have fractures. Fat travels to lungs and brain leading to shortness of breath, loss of consciousness, death…

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Ostepenia below the age of 50… what might be some of the differentials diagnoses you might predict???

Due to excess corticosteroids (endogenous or exogenous)
Hyperparathyroidism
Hyperthyroidism
Poor nutrition/malabsorption
Immobilization
Hypogonadism
Multiple other disease associations

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SEcondary problem due to kyphosis?

Poor ventilation due to hunch can lead to increased susceptibility of pneumonia

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Best prevention to osteoporosois

max peak bone mass (teen/young adults) nutrition and stuff

Encourage weight-bearing exercise and Ca supplemnetation

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What causes hypercalcemia?

primary hyperplasia or NEOPLASTIC enlargement of parathyroid glands

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How can kidney disease affect the skeleton?

Secondary hyperparathyroidism (renal disease) may also produce gross skeletal change.

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Classic indication of hyperparathyroidism?

Increase Ca and decreased Phosphorous

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Is increased calcium important to look into?

Yes, you need to find out the cause

90% of all cases due to malignancy and hyperparathyroidism

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Causes of osteomalacia:

Environmental: classic childhood rickets
Poor diet + sun exposure in northern latitudes

Intestinal malabsorption—commonest cause of Vit D deficiency in USA

Liver or renal disease (impaired hydroxylation of Vit D)

Rare congenital/inborn errors of metabolism

Deficient Vit D hydroxylation
Renal tubular phosphate leak
End organ resistance to Vit D (OH)2

Difference in diagnosing osteoporosis and osteomalacia?

Osteomalacia has these signs:

Increased serum alkaline phosphatase (>90%)
Low serum Ca or P (50%)
Decreased urinary Ca excretion (33%)
Increased PTH (40%)
Decreased 1, 25 dihydroxyvitamin D3 (50%)

Where does Vit D come from and where is it hydroxylated?

Vit D comes from diet and skin synthesis

It is first hydroxylated in the liver and then secondly in the kidney

In the kidney, it is PTH that stimulates the hydroxylation

What stimulates secretion of PTH (parathyroid hormone)

Hypocalcemia

How do PTH and Vit D affect the Ca levels in the intestine, kidney, bone and blood?

Kidney

PTH stimulates production of Vit D
PTH increases Resorbtion of Ca
PTH cause excretion of P

Bone
-Vit D and PTH stimulate transferring Ca from bone into the blood

Intestine
-PTH and Vit D stimulate increase in absorbtion of Ca and P from the intestine into the blood

Why is osteoporosis so common in older women?

Ability of kidneys to hydroxylate Vit D(OH)1 to Vit D(OH)2 becomes impaired with age
Diminished PTH secretion by parathyroid glands in response to hypocalcemia
Increased osteoclastic activity
Decreased ability of osteoblasts to make matrix

MOst common bacteria in suppurtative osteomyelitis?

Staph Aureus

What fungi cause fungal osteomyelitis?

Blastomycosis and coccidioidomycosis: Commonest causes of fungal osteomyelitis in non-immunosuppressed patients Almost always 2° to hematogenous spread from lungs; original pulmonary infection may have gone undiagnosed or be asymptomatic

Very painful location of osteomyelitis?

Vertebral osteomyelitis

Sickle cell patients tend to get what kind of infection in their bones? (osteomyelitis)

Salmonella

What it Paget's Disease of bone?

Deforming bone disease of middle-aged to elderly adults Current theory: Due to a latent viral infection of osteoclasts in a genetically susceptible person Affects up to 10-15% of elderly population (esp. Anglo-Saxon heritage) Rare in Asians, Africa, India, Scandinavia

What are the three phases of Paget's disease?

Lytic— increased osteoclasts with bone resorption/increased vascularity Mixed—Increased osteoclasts with increased osteoblasts, increased vascularity Sclerotic—most characteristic radiologically (osteoblastic phase)

What would you see in radiological images of Paget's Disease?

Most patients asymptomatic Widening / bowing of long bones Distorted / widened pelvic bones General weakening of affected bone causing increased fractures

Biochemically, as a physician you would suspect Paget's if:

Older patient Isolated increased alkaline phosphatase level Normal serum calcium No hepatobiliary disease

What is osteogenesis imperfecta?

Congenital disorders of type 1 collagen Either qualitatively abnormal or quantitatively too little Result: -insufficient / inadequate collagen for normal osteoid production - Osteopenia/osteoporosis -tendency toward fractures

What is osteopetrosis?

Thicken bone, a lot more osteoblast rather than osteoclast activity Loss of balance Thick and chalk-like, so big but still easy to break

What can x-rays help to predict about tumours involving the bones?

Likelihood of primary vs metastatic lesion Ability to subtype primary bone tumors by location and x-ray character Usually accurate in separating benign from malignant lesions By x-ray, tumors can be classified as either: - osteolytic (demineralizing effect) - osteoblastic (increased bone density relative to normal bone) - mixed osteolytic/osteoblastic features

Example of purely osteolytic bone malignancy?

Myeloma - Multifocal osteolytic lesions with bone pain - Often associated hypercalcemia - Fractures common

Example os purely osteoblastic bone malignancy?

metastatic prostate cancer

Why can leukemia sometimes be misdiagnosed as childhood rheumatoid arthritis?

acute leukemia alsways involves the bone marrow Can produce diffuse bone or joint pain when the lymphocytes enter the periosteum pain that almost seems like rheumatoid arthritis

What are bone fibromas?

CommonEST bone legion (not a neoplasm) Can be found in 1/3 of growing children Only a small fraction present clinically & need Rx Pain Pathologic fractures sometimes occur Often spontaneously regress

CommonEST primary malignant tumor in: Children AND Adults

Children: Osteosarcoma AND Adults: Chondorsarcoma

Abnormal thickening of the cortex of bones, usually long bones

osteoid osteoma

What kinds of bones do benign vs malignant cartilage tumors tend to involve?

Chondromas - small bones Chondrosarcomas - large bones

epiphysis is targeted by this type of tumor

giant cell tumor

The most aggressive/lethal of all primary bone tumors?

Ewing's sarcoma!

One thing I didn't get: How does kidney disease even affect the skeleton?

Impaired kidneys lose the ability to remove phosphorus from the blood which causes serum phosphate levels to increase. Phosphorus is involved in the regulation of calcium, high blood levels of phosphorus cause calcium to drop. If calcium levels drop, the parathyroid glands in the neck secrete parathyroid hormone which pulls calcium from the bones to compensate. This gradually and silently weakens the bones. Called renal osteodystrophy.