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Pathoma > Bone > Flashcards

Bone Flashcards

1
Q

Cause of achondroplasia

A

Activating mutation in fibroblast growth receptor 3 (FGFR3); AD
FGF3 inhibits growth, becomes over-expressed

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2
Q

Achondroplasia - clinical features, what is not affected

A

Short extremities, normal sized head and chest

Mental function, fertility and life span are not affected

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3
Q

Achondroplasia - what type of bone formation is affected

A

Endochondral bone formation: characterized by the formation of a cartilage matrix that is replaced with bone
ex/ long bones

vs. intramembranous bone formation: bone formed without a preexisting cartilage matrix
ex/ flat bones (skull and rib cage)

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4
Q

OI: what type of defect

A

Autosomal dominant defect in collagen type I synthesis

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5
Q

OI: clinical features

A

Multiple fractures, blue sclera (scleral collagen thins revealing underlying choroidal veins), hearing loss

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6
Q

Osteopetrosis is due to poor…

A

osteoclast function

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7
Q

Important genetic variant for osteopetrosis

A

Carbonic anhydrase II mutation -> loss of acidic environment necessary for bone resorption

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8
Q

Clinical features of osteopetrosis (5)

A
  1. Bone fractures
  2. Anemia, thrombocytopenia, and leukopenia with extramedullary hematopoiesis
  3. Vision and hearing impairment (impingement on CN)
  4. Hydrocephalus (narrowing of foramen magnum)
  5. Renal tubular acidosis - seen with CAII mutation, lack of CA results in decreased tubular reabsorption of HCO3- leading to metabolic acidosis
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9
Q

Treatment of osteopetrosis

A

Bone marrow transplant (osteoclasts are derived from monocytes)

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10
Q

Rickets/Osteomalacia is due to…

A

defective mineralization of osteoid (due to low Vitamin D). Osteoblasts normally produce osteoid which is then mineralized with calcium and phosphate to form bone.

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11
Q

Rickets most commonly arises before age 1 and presents with what four deformities?

A

Pigeon breast deformity
Rachitic rosary
Bowing of the legs (seen in ambulating children)
Frontal bossing (enlarlged forehead due to osteoid deposition on the skull)

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12
Q

Laboratory findings: Osteomalacia

A

Low Ca++, Phosphate
High PTH
High Alkaline phosphatase

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13
Q

Osteoporosis shows a reduction in which type of bone?

A

Trabecular (cancellous or spongy)

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14
Q

What factors influence peak bone mass? What causes bone mass to be lost more quickly?

A

Diet, exercise and genetics attribute to peak bone mass

Lack of weight bearing exercise (space travel), poor diet and decreased estrogen (menopause)can cause bone mass to be lost more quickly

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15
Q

Laboratory findings: Osteoporosis

A

Calcium, phosphate, PTH and alkaline phosphatase are all normal!

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16
Q

What causes Paget’s disease? At what age is this usually seen?

A

Imbalance between osteoclast and osteoblast function (localized - does not involve the entire skeleton)
Etiology unknown - possibly viral
>60 years

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17
Q

Paget disease biopsy will show…

A

Mosaic pattern of lamellar bone

18
Q

Clinical features of Paget disease of bone (5)

A 
Increased hat size
Bone pain (micro fractures)
Hearing loss (impingement on cranial nerve)
Lion-like facies (craniofacial bones)
Isolated elevated alkaline phosphatase
19
Q

Complications of Paget disease

A

High-output cardiac failure - due to formation of AV shunts in bone
Osteosarcoma (osteoblasts become mutated)

20
Q

Where does the bacteria seed in osteomyelitis in adults vs. kids?

A

Adults - Epiphysis

Kids - Metaphysis

21
Q

6 common causes of osteomyelitis and what they are associated with -

A

Staph aureus - most common cause (90% of cases)
N gonorrhoeae - sexually active young adults
Salmonella - sickle cell disease
Pseudomonas - diabetics or IV drug users
Pasteurella - associated with dog or cat bite/scratches
Mycobacterium tuberculosis - usually involves the vertebrae (Pott disease)

22
Q

Clinical features of osteomyelitis (sequestrum vs. involucrum)

A 
Bone pain with systemic signs of infection (fever, leukocytosis)
Lytic focus (abscess - sequestrum) surrounded by sclerosis (involucrum) of bone on x-ray
23
Q

What is the most common benign soft tissue tumor in adults? In children?

A

Lipoma (benign tumor of adipose tissue)

Rhabdomyosarcoma (rhabdomyoblast is characteristic cell, desmin positive, most common sites include head/neck/vagina)

24
Q

What is cardiac rhabdomyoma associated with?

A

Tuberous sclerosis (rare genetic disease that causes benign tumor growth in the brain and other vital organs)

25
Q

Most common malignant soft tissue tumor in adults?

A

Liposarcoma (lipoblast is characteristic cell - adipose precursor cell)

26
Q

Metastatic bone tumors are more common than primary. What type of lesion do they produce?

A

Osteolytic (punched out) lesions

Exception - prostatic carcinoma classically produces osteoblastic lesions

27
Q

Chondroma vs. Chondrosarcoma (location)

A

Chondroma is a benign tumor of the cartilage. It usually arises in the medulla of small bones of the hands and feet

Chondrosarcoma is a malignant cartilage-forming tumor. Usually arises in the medulla of the pelvis or central skeleton

28
Q

Osteoma most commonly arises where? Associated with what?

A

Benign tumor of bone
Surface of facial bones
Associated with Gardner syndrome (multiple benign tumors and colon polyps)

29
Q

What is an osteoid osteoma? Who does it most commonly occur in? Where? What does it present as?

A

Benign tumor or osteoblasts (produce osteoid) surrounded by a rim of reactive bone
Occurs in young adults (<25 ), more common in males
Arises in the cortex of long bones (femur)
Presents as bone pain that resolves with aspirin

30
Q

How is an osteoblastoma different from and osteoid osteoma?

A

Osteoblastomas are similar but larger (>2cm), arise in the vertebrae and present as bone pain that does not respond to aspirin

31
Q

Osteochondroma: What is it, from where, what can it transform to?

A

A tumor of the bone with a cartilaginous cap
Arises from a lateral projection of the growth plate (metaphysics); bone is continuous with the marrow space
Overlying cartilage can transform (rarely) to chondrosarcoma

32
Q

What is the most common benign tumor of bone?

A

Osteochondroma

33
Q

Osteosarcoma - Proliferation of what? Most common in what age group? Arises where? How does it present?

A

Malignant proliferation of osteoblasts
Peak incidence in teenagers (bimodal, also seen in elderly)
Arises in metaphysics of long bones (usually distal femur or proximal tibia - around the knee)
Presents as a pathological fracture (tumor weakens the bone) or bone pain with swelling

34
Q

Imaging sign seen with osteosarcoma

Biopsy

A

Destructive mass with a ‘sunburst’ appearance and lifting of the periosteum (Codman triangle)
Biopsy shows pleomorphic cells that produce osteoid (pink)

35
Q

Risk factors for osteosarcoma

A

Familial retinoblastoma, Paget disease, radiation exposure

36
Q

Giant cell tumor (what is it, what age, where does it arise, prognosis, appearance on x-ray)

A

Tumor comprised of multinucleated giant cells and stromal cells
Occurs in young adults
Arises in the epiphysis of long bones (distal femur or proximal tibia - knee)
Locally aggressive, may recur
Soap bubble appearance on x-ray

37
Q

Soap bubble appearance on x-ray is associated with what tumor?

A

Giant cell tumor

38
Q

What is the only bone tumor that arises in the epiphysis?

A

Giant cell tumor

39
Q

Ewing sarcoma (what, where, who, x-ray, biopsy, translocation and prognosis)

A

Malignant proliferation of poorly-differentiated cells derived from neuroectoderm. Arises in the diaphysis of long bones; usually in male children (>15). Onion skin appearance on x-ray (layering of new bone by periosteum). Biopsy reveals small, round blue cells that resemble lymphocytes (can be confused with lymphoma or chronic osteomyelitis). t(11;22) translocation is characteristic. Often presents with metastasis, responsive to chemotherapy

40
Q

Onion skin appearance on x-ray

A

Ewing sarcoma

41
Q

Where do these tumors occur?

Osteoma
Osteoid osteoma
Osteochondroma
Osteosarcoma

A

Osteoma - surface of facial bones
Osteoid osteoma - cortex of long bones
Osteochondroma - lateral projection of the growth plate (metaphysis)
Osteosarcoma - metaphysis

42
Q

Where do these tumors occur?

Giant cell tumor
Ewing sarcoma
Chondroma
Chondrosarcoma

A

Giant cell tumor - epiphysis
Ewing sarcoma - diaphysis
Chondroma - medulla of hands and feet
Chondrosarcoma - medulla of pelvis or central skeleton

Pathoma (6 decks)

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