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STEP 1 Pathoma > Chapter 18 > Flashcards

Chapter 18 Flashcards

1
Q

What causes acondroplasia?

A

Activating mutation in FGFR3 (AD) where overactivation inhibits endochondrial ossification but not intramembranous bone formation (normal sized head)

Mental function, life span, and fertility are not affected

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2
Q

What is osteogenesis imperfecta?

A

Congenital defect of bone formation resulting in structurally weak bone, most commonly due to a AD defect in type 1 collagen synthesis

May present with fractures, blue sclera, and hearing loss

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3
Q

What is osteopetrosis?

A

An inherited defect of bone resorption due to poor osteoclast function resulting in abnormally thick, heavy bone that fractures easily

Most commonly due a mutation in carbonic anhydrase II leading to a loss of acidic microenvironment required for bone resorption

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4
Q

How might osteopetrosis present?

A

bone fractures

anemia, thrombocytopenia, and leukemia with extramedullary hematopoiesis due to bony replacement of the marrow

Vision and hearing impairment

Hydrocephalus due to narrowing of the foramen magnum

Renal tubular acidosis

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5
Q

How is osteopetrosis tx?

A

Bone marrow transplant

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6
Q

What causes rickets/osteomalacia?

A

Defective mineralization of osteoid (osteoblasts normally produce osteoid, which is then mineralized with calcium and phosphate to form bone) typically due to low vitD, resulting in low levels of calcium and phosphate

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7
Q

How is vitD activted?

A

25-hydroxylation in the liver and then 1,25-hydroxylaton via 1a-hydroxylase in the proximal tubule

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8
Q

How does vitD act?

A

Increases serum calcium and phosphate by acting on:

  • Intestine to increase absorption of calcium and phospahte
  • Kidney to increase reabsorption of both
  • bone to increase resorption of both into serum
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9
Q

How does rickets present?

A

Pigeon-breast deformity-inward bending of the ribs with anterior protrusion of the sternum

Frontal bossing (enlarged forehead)- due to osteoid deposition in the skull

Rachitic rosary due to osteoid deposition at the costochondral junction

Bowing of the legs

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10
Q

What is osteoporosis?

A

Reduction in trabecular bone mass resulting in porous bone with an increased risk for fracture

Risk is based on the peak bone mass and rate of bone loss therafter

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11
Q

What are the most common forms of osteoporosis?

A

senile and postmenopausal

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12
Q

What are the lab findings of osteoporosis?

A

serum calcium, phosphate, PTH, and alkaline phosphatase are normal (helps exlcude osteomalacia which has a similar presentation but low calcium and phosphate, and increased Alk phos)

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13
Q

T or F. Glucocorticoids are contraindicated with osteoporosis

A

T. Makes worse

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14
Q

What causes Paget disease of bone?

A

LOCALIZED (not systemic) imbalance between osteoclast and osteoblast function usually occurring in late adulthood (avg. age 60+)

Etiology unknown, but possibly viral

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15
Q

What are the stages of Paget disease?

A

osteoclastic

mixed blastic-clastic

osteoblastic

With an end result of a thick, sclerotic bone that fractures easily

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16
Q

Describe the histo appearance of Paget disease of bone

A

Mosaic

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17
Q

How does Paget disease of bone present?

A

Bone pain due to microfractures

Increasing skull/hat size

  • Hearing loss due to CN impingement
  • Lion facies
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18
Q

What are the major complications of Paget disease of bone?

A

High-output cardiac failure

Osteosarcoma

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19
Q

What is osteomyelitis?

A

infection of marrow and bone usually occurring in children and most commonly due to bacterial infection arising from heme spread (transient bacteremia seeds the metaphysis, while open-wound bacteremia (adults) seedss the epiphysis)

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20
Q

What are the major causes of osteomyelitis?

A

S. aureus (90%)

N. gonorhoeae- sexually active adults

Salmonella-sickle cell disease

Pseudomonas- diabetics or IVDU

Pasteurella- cat or dog bites

Mycobacterium- usually Potts disease

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21
Q

How does osteomyelitis present?

A

Bone pain with systemic signs of infection (e.g. fever and leukocytosis)

Lytic focus (abscess) surrounded by sclerosis of bone on x-ray (i.e. sequestrum surrounded by involucrum)

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22
Q

What is avascular (aseptic) necrosis?

A

Ischemic necrosis of bone and bone marrow

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23
Q

What are the major causes of avascular (aseptic) necrosis?

A

Caisson disease (the bends)

Trauma/fracture

Steroids

Sickle cell

Legg-Calve Perthes Disease

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24
Q

What is Legg-Calve Perthes Disease?

A

Legg–Calvé–Perthes disease (LCPD) is a childhood hip disorder initiated by a disruption of blood flow to the femoral head. Due to the lack of blood flow, the bone dies (osteonecrosis or avascular necrosis) and stops growing. Over time, healing occurs by new blood vessels infiltrating the dead bone and removing the necrotic bone which leads to a loss of bone mass and a weakening of the femoral head. The bone loss leads to some degree of collapse and deformity of the femoral head and sometimes secondary changes to the shape of the hip socket. It is also referred to as idiopathicavascular osteonecrosis of the capital femoral epiphysis of the femoral head since the cause of the interruption of the blood supply of the head of the femur in the hip joint is unknown.

The condition is most commonly found in children between the ages of 4 and 8, but it can occur in children between the ages of 2 and 15. The main long-term problem with this condition is that it can produce a permanent deformity of the femoral head, which increases the risk of developing osteoarthritis in adults. It is also commonly known as Perthes disease, or Legg–Perthes disease. Perthes is a form of osteochondritis which only affects the hip, although other forms of osteochondritis can affect elbows, knees, ankles, and feet. Bilateral Perthes, which means both hips are affected, should always be investigated thoroughly to rule out multiple epiphyseal dysplasia.

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25
Overview of osteoma
Benign tumor of bone, most commonly arising on the surface of facial bones and associated with Gardner syndrome
26
Describe osteoid osteomas
A **_benign_** tumor of osteoblasts (that produce osteoid) surrounded by a rim of reactive rim commonly occurring in **young adults less than 25 yo** (more common in males) and classically arising in the **cortex of long bones like the femur**
27
How might a osteoid osteoma present?
Presents as bone pain that **resolves with aspirin**
28
What should be on the Ddx for osteoid osteoma?
Osteoblastoma which is larger (2+cm, while osteoid osteomas are smaller), arise in the vertebrae, and presents as bone pain that does not respond to aspirin
29
Describe osteochondromas
Tumor of bone with an overlying cartilage cap (most common benign tumor of bone) arising from a lateral projection of the growth plate (metaphysis) Can rarely transform to chondrosarcoma
30
A malignant proliferation of osteoblasts would be called a \_\_\_\_\_\_\_
osteosarcoma
31
Who commonly gets osteosarcoma?
peak incidence is seen in teenagers, and less commonly in the elderly
32
What are the major risk factors for osteosarcoma?
Familial retinoblastoma, Paget disease, and radiation exposure
33
Where do osteosarcomas arise?
The metaphysis of long bones, usually the distal femur or proximal tibia
34
What is a classic x-ray finding of osteosarcoma?
35
Describe giant cell tumors
Tumor composed of multinucleated giant cells and stromal cells (occurs in young adults) arising in the EPIPHYSIS of long bones, usually the distal femur or proximal tibia "soap bubble" appearance on x-ray Local aggressive, and may recur
36
What is Ewing sarcoma?
Malignant proliferation of poorly-differentiated cells derived from NEUROECTODERM arising in the diaphysis of long bones usually in males less than 15 yo Classic 'onion skin' appearance on x-ray
37
Describe the histo of a Ewing Sarcoma
38
Where do chondromas (benign tumor of cartilage) arise?
medulla of small bones of the hands and feet
39
Where do chrondrosarcomas arise?
malignant cartilage-forming tumor arising in the medullar of the pelvis or central skeleton
40
The articular surface of adjoining bones is made of what?
hyaline cartilage (type II collagen) surrounded by a joint capsule
41
What is osteoarthritis?
progressive degeneration of articular cartilage (most common type of arthritis) due to wear and tear with major risk factors including age, obesity, and trauma
42
How does osteoarthritis present?
stiffness in the morning that worsens dring the day
43
Pathologic features of osteoarthritis?
Disruption of the cartilage that lines the articular surface Eburnation of the subchondral bone Osteophyte formation
44
What is rheumatoid arthritis?
Chronic, systemic autoimmune disease classically arising in women of late childbearing age (associated with HLA-DR4)
45
How does RA present?
Arthritis with morning stiffness that improves with activity (symmetric involvement of the PIP joints of the finger, elbows, ankles, and knees are characteristics, with the DIP usually being spared) Fever, malaise, weight loss, and myalgias Baker cyst- swelling of burse behind the knee Nodules vasculitis
46
What are the seronegative sponydloarthropathies?
A group of joint disorders marked by: Lack of rheuamtoid factor (IgM autoantibody against the Fc region of IgG) Axial skeleton involvement HLA-B27 association
47
What are the major seronegative sponydloarthropathies?
Ankylosing spondylarthritis Reither syndrome Psoriatic arthritis
48
What is Ankylosing spondylarthritis?
Involves the sacroiliac joint and spine in mostly males presenting as lower back pain, eventually leading to vertebral fusion (bamboo spine) May present with uveitis and aortitis
49
What is the triad of Reiter syndrome?
Arthritis, urethritis, and conjunctivitis
50
What are the most common causes of infectious arthritis?
N. gonorhoeae (young adults; most common cause) S. aureus (older children and adults) Classically involves only a single joint, usually the knee (elevated ESR may be present)
51
What is gout?
Deposition of monosodium urate crystals in tissues, esp. the joints due to hyperuricemia
52
Secondary gout is seen with:
Leukemia and myeloproliferative disorders-increased cell turnover Lesch-Nyhan syndrome- X-linked deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) Renal insufficiency (decreased excretion)
53
Chronic gout can lead to:
Development of tophi- white, chalky aggregates of uric acid crystals with fibrosis and giant cell rxn in soft tissue and joints Renal failure- urate crystals may deposit in kidney tubules (urate nephropathy)
54
Synovial fluid showing rhomboid shaped crystals would suggest what diagnosis?
Pseudogout (with positive birefringence; gout= negative birefringence)
55
What is dermatomyositis?
Inflammatory disorder of the skin and skeletal muscle with an unknown cause (but some cases are associated with gastric carcinoma)
56
How might dermatomyositis present?
Bilateral proximal muscle weakness, with distal involvement a late finding Rash of teh upper eyelids (Heliotrope rash), or malar rash Red papules on the elbows, knuckles, and knees (Gottronn papules) Shaw sign
57
What are the lab findings of dermatomyositis?
Increased creatine kinase positive ANA and anti-Jo-1 Ab **Perimysial** inflammation (CD4)
58
Tx of dermatomyositis?
Steroids
59
Describe polymyositis
Inflammatory disorder of skeletal muscle classically seen in child-bearing women, with clinical symptoms similar to dermatomyositis but without skin involvement Endomysial inflammation (CD8 cells)
60
What causes X-linked muscular dystrophy?
Degenerative disorder marked by muscle wasting and replacement of skeletal muscle by ADIPOSE tissue due to defects in the dystrophin gene (anchors the muscle cytoskeleton to the ECM)
61
Contrast Becker vs. Duchenne muscular dystrophy
Duchenne- deletion of dystrophin Becker- mutated dystophin (milder)
62
Death is msucular dystrophy is usually due to what?
Cardiac or respiratory failure (myocardium is usually involved)
63
What causes myasthenia gravis?
Abs agains the POSTsynpatic ACh receptor at the NMJ (more common in women)
64
How does myasthenia gravis present?
**Muscle wekaness** that worsens with use and improves with rest; classically involves the eyes, leading to **ptosis and diplopia**
65
Myasthenia gravis is classically associated with what?
Thymic hyperplasia or thymoma
66
What causes Lambert-Eaton syndrome?
Abs against the PREsynaptic calcium chanells of the NMJ, piaring ACh release (arises classically as a pareneoplastic syndrome, most commonly due to small cell lung carcinoma) Eyes usually spared, but proximal muscle weakness seen
67
Describe lipomas
Benign tumor of adipose tissue, most common benign soft tissue in adults
68
Describe liposarcomas
Malignant tumor of adipose tissue, with classic **lipoblast cells**
69
Cardiac rhabdomyomas are assoicated with \_\_\_\_\_\_\_
Tuberous sclerosis
70
Describe rhabdomyosarcomas
Malignant tumor of skeletal muslce (most common malignant soft tissue tumor in children) Rhabdomyoblast is the classic cell; desmin positive Most common site is the head/neck and the vagina in young girls

STEP 1 Pathoma (18 decks)

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