CH18 - Musculoskeletal Pathology Flashcards Preview

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Flashcards in CH18 - Musculoskeletal Pathology Deck (244):
1

What is achondroplasia?

Impaired cartilage proliferation in the growth plate

2

What is achondroplasia a common cause of?

dwarfism

3

What is achondroplasia due to?

an activating mutation in fibroblast growth factor receptor 3 (FGFR3) Autosomal dominant

4

What does the overexpression of FGFA3 do?

It inhibits growth

5

What are most mutations for achondroplasia?

they are sporadic and related to increased paternal age.

6

What are the clinical features for achondroplasia?

Short extremities with normal-sized head and chest?

7

In achondroplasia, why is there short extremities with normal-sized head and chest?

its due to poor endochondral bone formation; intramembranous bone formation is not affected.

8

How is endochondral bone formation characterized?

by formation of a cartilage matrix, which is then replaced by bone; it is the mechanism by which long bones grow.

9

How is intramembranous bone formation characterized?

by formation of bone without a preexisting cartilage matrix; it is the mechanism by which fiat bones (e.g., skull and rib cage) develop.

10

In achondroplasia, what aspects are not affected?

Mental function, life span, and fertility are not affected

11

What is osteogenesis imperfecta?

It?s a congenital defect of bone resorption resulting in structurally weak bone

12

What is osteogenesis imperfecta most commonly due to?

an autosomal dominant defect in collagen type 1 synthesis

13

What is blue sclera?

thinning of scleral collagen reveals underlying choroidal veins.

14

What are the clinical features for osteogenesis imperfecta?

1) Multiple fractures of bone (can mimic child abuse, but bruising is absent) 2) blue sclera?3) Hearing loss

15

Why is there hearing loss in osteogenesis imperfecta?

Bones of the middle ear easily fracture

16

What is osteoporosis?

inherited defect of bone resorption resulting in abnormally thick, heavy bone that fractures easily

17

What is osteoporosis due to?

Its due to poor osteoclast function

18

What is an example for the multiple genetic variants that exist for osteoporosis?

carbonic anhydrase II mutation leads to loss of the acidic microenvironment required for bone resorption

19

In osteoporosis, why is there anemia in osteoporosis?

It is due to bony replacement of the marrow (myelophthisic process)

20

What are the clinical features for osteoporosis?

1) Bone fractures 2) Anemia, thrombocytopenia, and leukopenia with extramedullar hematopoiesis 3) Vision and hearing impairment 4) hydrocephalus 5) renal tubular acidosis

21

In osteoporosis, why is there vision and hearing impairment?

due to impingement on cranial nerves

22

In osteoporosis, why is there renal tubular acidosis?

Its seen with carbonic anhydrase II mutation, a lack of carbonic anhydrase results in decreased tubular reabsorption of HCO3 leading to metabolic acidosis.

23

What is the treatment for osteoporosis?

It is bone marrow transplant; osteoclasts are derived from monocytes.

24

What do Ricketts and osteomalacia result in?

Defective mineralization of osteoid

25

What do osteoblasts normally produce?

Osteoid which is then mineralized with calcium and phosphate to form bone

26

What are Rickets and osteomalacia due to?

low levels of vitamin D, which results in low serum calcium and phosphate

27

What is vitamin D normally derived from?

the skin upon exposure to sunlight (85%) and from the diet (15%).

28

What does activation of Vitamin D require?

25-hydroxylation by the liver followed by 1-alphahydroxylatton by the proximal tubule cells of the kidney

29

What does active vitamin D do?

it raises serum calcium and phosphate

30

How does active Vitamin D raise serum calcium and phosphate?

by acting on the intestines, kidney and bone

31

What is the effect of active Vitamin D on the intestine?

It increases absorption of calcium and phosphate

32

What is the effect of active vitamin D on the kidney?

it increases reabsorption of calcium and phosphate

33

What is the effect of active vitamin D on bone?

It increases resorption of calcium and phosphate

34

In whom is vitamin D deficiency seen?

with decreased sun exposure (e.g.. northern latitudes), poor diet, malabsorption, liver failure, and renal failure.

35

What is Rickets due to?

due to low vitamin D in children, resulting in abnormal bone mineralization.

36

In whom does Rickets most commonly arise?

in children < 1 year of age

37

How do Rickets present?

1) Pigeon-breast deformity 2) Frontal bossing (enlarged lorehead) 3) Rachitic rosary 4) bowing of the legs may be seen in ambulating children

38

What is pigeon-breast deformity in Rickets?

It?s inward bending of the ribs with anterior protrusion of the sternum

39

What is the frontal bossing in Rickets due to?

The enlarged forehead is due to osteoid deposition on the skull

40

What is Rachitic rosary due to?

osteoid deposition at the costochondral junction

41

What is osteomalacia due to?

low vitamin D in adults.

42

What is seen in ostomalacia?

Inadequate mineralization which results in weak bone with an increased risk for fracture.

43

What are the laboratory findings for osteomalacia?

decreased serum calcium, decreased serum phosphate, increased PTH, and increased alkaline phosphatase

44

What is osteoporosis?

It?s a reduction in trabecular bone mass

45

What does osteoporosis result in?

porous bone with an increased risk for fracture

46

What is the risk of osteoporosis based on?

peak bone mass (attained in early adulthood) and rate of bone loss that follows thereafter

47

When is peak bone mass achieved?

by 30 years of age

48

What is peak bone mass based on?

it is based on (1) genetics (eg vitamin D receptor variants), (2) diet, and (3) exercise.

49

What happens to bone mass after age 30?

slightly less than 1% of bone mass is lost each year

50

What might cause bone mass to be lost more quickly (after age 30)?

with lack of weight-bearing exercise (eg space travel), poor diet, or decreased estrogen (e.g., menopause).

51

What are the most common forms of osteoporosis?

They are senile and postmenopausal.

52

What are the clinical features for osteoporosis?

Bone pain and fractures in weight-bearing areas such as the vertebrae (leads to loss of height and kyphosis), hip, and distal radius, Serum calcium, phosphate, PTH, and alkaline phosphatase are normal; labs help to exclude osteomalacia (which has a similar clinical presentation).

53

What must be excluded when osteoporosis is suspected? How is this done?

Osteomalacia and the labs help to exclude it

54

How is bone density measured?

using a DEXA scan

55

What is the treatment for osteoporosis?

1. Exercise, vitamin D, and calcium?limit bone loss 2. Bisphosphonates?induce apoptosis of osteoclasts 3. Estrogen replacement therapy is debated (currently not recommended). 4. Glucocorticoids are contraindicated (worsen osteoporosis).

56

What is paget disease of bone due to?

Imbalance between osteoclast and osteoblast function

57

When is paget disease of bone usually seen?

in late adulthood (average age > 60 years)

58

What is the etiology for Paget disease of bone?

It is unknown; possibly viral

59

Is Paget disease of bone localized or systemic?

It?s a localized process involving one or more bones; does not involve the entire skeleton

60

What are the three distinct stages of Paget disease of bone?

(1) osteoclastic, (2) mixed osteoblastic-osteoclastic, and (3) osteoblastic.

61

What is the end result for paget disease of bone?

it is thick, sclerotic bone that fractures easily

62

What does biopsy for Paget disease of bone reveal?

a mosaic pattern of lamellar bone

63

What are the clinical features for Paget disease of bone?

1) bone pain 2) increasing hat size 3) hearing loss 4) lion like faces 5) isolated elevated alkaline phophatase

64

In Paget disease of bone, why is there bone pain?

Its due to microfractures

65

In Paget disease of bone why is there increasing hat size?

Skull is commonly affected.

66

In Paget disease of bone, why is there hearing loss?

impingement on cranial nerve

67

In Paget disease of bone, why is there lion-like facies?

involvement of craniofacial bones

68

In Paget disease of bone, why is there isolated elevated alkaline phosphatase?

most common cause of isolated elevated alkaline phosphatase in patients > 40 years old

69

What is the treatment for Paget disease of bone?

1) calcitonin 2) bisphosphonates

70

Why does calcitonin help in Paget disease of bone?

It inhibits osteoclast function

71

Why does bisphosphonates help in Paget disease of bone?

It induces apoptosis of osteoclasts

72

What are the complications for Paget disease of bone?

1) High-output cardiac failure?due to formation of AV shunts in bone 2) Osteosarcoma

73

Why is there high-output cardiac failure as a complication for Paget disease of bone?

Its due to formation of AV shunts in bone

74

What is osteomyelitis?

Infection of marrow and bone

75

In whom does osteomyelitis usually occur?

in children

76

What type of infection is most commonly involved in osteomyelitis?

bacterial

77

In osteomyelitis, why would it most commonly arise?

It arises via hematogenous spread

78

What happens in osteomyelitis in children?

Transient bacteremia (children) seeds metaphysis.

79

What happens in osteomyelitis in adults?

Open-wound bacteremia (adults) seeds epiphysis.

80

What are the causes for osteomyelitis?

1) Staphylococcus 2) Gonorrhoeae 3) Salmonella 4) Pseudomonas 5) Pasteurella 6) Mycobacterium tuberculosis

81

What bacteria is the most common cause of osteomyelitis?

Staphylococcus aureus (90% of cases)

82

What is the cause of osteomyelitis in sexually active young adults?

gonorrhoeae

83

What is the cause of osteomyelitis in sickle cell disease patients?

Salmonella

84

What is the cause of osteomyelitis in diabetics or IV drug abusers?

Pseudomonas

85

What is the cause of ostoemyelitis in associated with cat or dog bite/scratches

pasteurella

86

What is the cause of ostoemyelitis in that usually involves vertebrae (Pott disease)?

mycobacterium tuberculosis

87

What are the clinical features for osteomyelitis?

1) Bone pain with systemic signs of infection (e.g., fever and leukocytosis) 2) Lytic focus (abscess) surrounded by sclerosis of bone on x-ray

88

What is the lytic focus in osteomyelitis called?

Sequestrum

89

What is the sclerosis in osteomyelitis called?

involucrum

90

How is the diagnosis for osteomyelitis made?

by blood culture.

91

What is avascular (aseptic) necrosis?

Ischemic necrosis of bone and bone marrow

92

What are the causes for avascular (aseptic) necrosis?

trauma or fracture (most common), steroids, sickle cell anemia, and caisson disease.

93

What are major complications for avascular (aseptic) necrosis?

osteoarthritis and fracture are major complications.

94

What are the bone tumors?

Osteoma, osteoid osteoma, osteochondroma, osteosarcoma, giant cell tumor, ewing sarcoma, chondroma, chondrosarcoma, metastatic tumors

95

What is osteoma?

Benign tumor of bone

96

Where does osteoma most commonly arise?

arises on the surface of facial bones

97

What is osteoma associated with?

Gardner syndrome

98

What is osteoid osteoma?

Benign tumor of osteoblasts (that produce osteoid) surrounded by a rim of reactive bone

99

In whom does osteoid osteoma occur?

in young adults < 25 years of age (more common in males)

100

Where does osteoid osteoma arise?

in cortex of long bones (e.g., femur)

101

How does osteoid osteoma present?

as bone pain that resolves with aspirin

102

In osteoid osteoma, what does imaging reveal?

a bony mass (< 2 cm) with a radiolucent core (osteoid)

103

How does osteoblastoma compare to osteoid osteoma?

it is similar to osteoid osteoma but is larger (> 2 cm), arises in vertebrae, and presents as bone pain that does not respond to aspirin

104

What is osteochondroma?

It is a tumor of bone with an overlying cartilage cap

105

What is the most common benign tumor of bone?

osteochondroma

106

How does osteochondroma arise?

from a lateral projection of the growth plate (metaphysis); bone is continuous with the marrow space.

107

Is there a connection between osteochondroma and cancer?

Overlying cartilage can transform (rarely) to chondrosarcoma.

108

What is osteosarcoma?

Malignant proliferation of osteoblasts

109

In whom is the Peak incidence for osteosarcoma seen?

in teenagers; less commonly seen in the elderly

110

What are the risk factors for osteosarcoma?

include familial retinoblastoma, Paget disease, and radiation exposure.

111

When does osteosarcoma arise?

in the metaphysis of long bones, usually the distal femur or proximal tibia (region of the knee)

112

How does osteosarcoma present?

as a pathologic fracture or bone pain with swelling

113

What does imaging for osteosarcoma reveal?

a destructive mass with a sunburst appearance and lifting of the periosteum

114

What does biopsy for osteosarcoma reveal?

pleomorphic cells that produce osteoid

115

What is giant cell tumor?

Tumor comprised of multinucleated giant cells and stromal cells

116

In whom does giant cell tumors occur?

in young adults

117

Where do giant cell tumors arise?

in the epiphysis of long bones, usually the distal femur or proximal tibia (region of the knee)

118

In giant cell tumors, what is seen on x-ray?

Soap-bubble appearance on x-ray

119

Are giant cell tumors aggressive or benign?

its locally aggressive tumor; may recur

120

What is ewing sarcoma?

Malignant proliferation of poorly-differentiated cells derived from neuroectoderm

121

Where does ewing sarcoma arise?

in the diaphysis of long bones; usually in male children (< 15 years of age)

122

For ewing sarcoma, what is the appearance on x-ray?

Onion-skin appearance on x-ray

123

What does biopsy for ewing sarcoma reveal?

small, round blue cells that resemble lymphocytes

124

What might ewing sarcoma be confused with?

lymphoma or chronic osteomyelitis

125

What translocation is characteristic of ewing sarcoma?

T(11;22)

126

How does ewing sarcoma often present?

with metastasis

127

Does ewing sarcoma respond to chemotherapy?

yes

128

What is chondroma?

Benign tumor of cartilage

129

Where does chondroma usually arise?

in the medulla of small bones of the hands and feet

130

What is chondrosarcoma?

Malignant cartilage-forming tumor

131

Where does chondrosarcoma arise?

in medulla of the pelvis or central skeleton

132

Which are more common, primary or metastatic tumors of the bone?

Metastatic tumors are more common than primary tumors

133

What do metastatic tumors usually result in?

osteolytic (punched-out) lesions

134

What classically produces osteoblastic lesions?

Prostatic carcinoma.

135

What is a joint?

Connection between two bones

136

How do joints provide structural strength?

Solid joints are tightly connected (eg cranial sutures)

137

What are synovial joints?

They have a joint space to allow for motion

138

What is the articular surface of adjoining bones in a synovial joint made of?

hyaline cartilage (type II collagen) that is surrounded by a joint capsule

139

What facilitates smooth motion of the synovial joint?

Synovium lining the joint capsule secretes fluid rich in hyaluronic acid to lubricate the joint and facilitate smooth motion.

140

What is osteoarthritis?

Progressive degeneration of articular cartilage; most common type of arthritis

141

What is the most common type of arthritis?

osteoarthritis

142

What is osteoarthritis most often due to?

wear and tear

143

What is the major risk factor for osteoarthritis?

Age

144

In whom is osteoarthritis common?

after 60 years

145

In addition to age, what are some additional risk factors for osteoarthritis?

obesity and trauma.

146

What joints are affected by osteoarthritis?

a limited number of joints (oligoarticular); hips, lower lumbar spine, knees, and the distal interphalangeal joints (DIP) and proximal interphalangeal joints (PIP) of fingers are common sites

147

What is the classic presentation for osteoarthritis?

joint stiffness in the morning that worsens during the day

148

What are the pathologic features for osteoarthritis?

1) Disruption of the cartilage that lines the articular surface; fragments of cartilage floating in the joint space are called joint mice 2) Eburnation of the subchondral bone 3) Osteophyte formation (reactive bony outgrowths); classically arises in the DIP (Heberden nodes) and PIP (Bouchard nodes) joints of the lingers

149

What are Heherden nodes?

Osteophyte formation in distal interphalangeal joints

150

What are Bouchard nodes?

Osteophyte formation in proximal interphalangeal joints

151

What is rheumatoid arthritis?

Chronic, systemic autoimmune disease

152

In whom does rheumatoid arthritis classically arise?

in women of late childbearing age

153

What is rheumatoid arthritis associated with?

HLA-DR4

154

What is rheumatoid arthritis characterized by?

involvement of joints

155

What is the hallmark for rheumatoid arthritis?

synovitis leading to formation of a pannus (inflamed granulation tissue).

156

What does rheumatoid arthritis lead to?

destruction of cartilage and ankylosis (fusion) of the joint

157

What are the clinical features for rheumatoid arthritis?

1) Arthritis with morning stiffness that improves with activity 2) Fever, malaise, weight loss, and myalgias 3) Rheumatoid nodules 4) Vasculitis 5) Baker cyst 6) Pleural effusions, lymphadenopathy, and interstitial lung fibrosis

158

For rheumatoid arthritis, describe the arthritis that is seen clinically?

Symmetric involvement of PIP (proximal interphalangeal joints) joints of the fingers (swan-neck deformity), wrists (ulnar deviation), elbows, ankles, and knees is characteristic; DIP (distal interphalangeal joints) is usually spared (unlike osteoarthritis)

159

What is a difference between the arthritis seen in rheumatoid arthritis and osteoarthritis?

In rheumatoid arthritis the DIP is usually spared unlike osteoarthritis

160

For rheumatoid arthritis, what is seen on x-ray?

Joint-space narrowing, loss of cartilage, and osteopenia

161

What are rheumatoid nodules?

They are a central zone of necrosis surrounded by epithelioid histiocytes; arise in skin and visceral organs

162

What is vasculitis?

Multiple organs may be involved.

163

What is Baker cyst?

swelling of bursa behind the knee

164

What are the laboratory findings for rheumatoid arthritis?

1) IgM autoantibody against Fc portion of IgG (rheumatoid factor); marker of tissue damage and disease activity 2) Neutrophils and high protein in synovial fluid

165

What are the complications for rheumatoid arthritis?

anemia of chronic disease and secondary amyloidosis

166

What are the seronegative spondyloarthropathies?

1) Ankylosing spondylarthritis 2) Reiter syndrome 3) Psoriatic arthritis

167

What characterizes seronegative spondyloarthropathies?

It?s a group of joint disorders characterized by 1) Lack of rheumatoid factor 2) Axial skeleton involvement 3) HLA-B27 association

168

What does ankylosing spondylarthritis involve?

the sacroiliac joints and spine.

169

In whom does ankylosing spondylarthritis arise?

in young adults, most often male

170

How does ankylosing spondyloarthritis present?

with low back pain; involvement of vertebral bodies eventually arise leading to fusion of the vertebrae - bamboo spine

171

What are the extra-articular manifestations for ankylosing spondylarthritis?

They include uveitis and aortitis (leading to aortic regurgitation)

172

What is reiter syndrome characterized by?

the triad of arthritis, urethritis, and conjunctivitis.

173

In whom does Reiter syndrome arise?

in young adults (usually males) weeks after a GI or Chlamydia trachomatis infection

174

Psoriatic arthritis is seen in whom?

10% of cases of psoriasis.

175

What does psoriatic arthritis involve?

axial and peripheral joints; DIP joints of the hands and feet are most commonly affected, leading to sausage fingers or toes

176

What is infectious arthritis?

Arthritis due to an infectious agent, usually bacterial

177

What are the causes for infectious arthritis?

1) N. gonorrhoeae 2) S. aureus

178

What is the most common cause for infectious arthritis overall?

N. gonorrhoeae (its seen in young adults)

179

What is the 2nd most common cause of infectious arthritis overall?

S. aureus, and is seen in older children and adults

180

What does infectious arthritis classically involve?

It classically involves a single joint, usually the knee

181

What does infectious arthritis present as?

a warm joint with limited range of motion; fever, increased white count, and elevated ESR are often present

182

What is gout?

Deposition of monosodium urate (MSU) crystals in tissues, especially the joints

183

What is gout due to?

hyperuricemia; related to overproduction or decreased excretion of uric acid

184

Where is uric acid derived from?

purine metabolism

185

What excretes uric acid?

It is excreted by the kidney

186

What is the most common cause of gout?

Primary gout is the most common form;

187

What is the etiology of hyperuricemia?

it is unknown

188

What is secondary gout seen with?

1) Leukemia and myeloproliferative disorders 2) Lesch-Nyhan syndrome 3) Renal insufficiency

189

How does leukemia and myeloproliferative disorders lead to gout?

Increased cell turnover leads to hyperuricemia

190

How does Lesch-Nyhan syndrome lead to gout?

X-linked deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) (which is the salvage pathway); presents with mental retardation and self-mutilation

191

How does renal insufficiency lead to gout?

decreased renal excretion of uric acid

192

How does gout present?

as exquisitely painful arthritis of the great toe (podagra)

193

Why does gout present as podagra?

1. MSU crystals deposit in the joint, triggering an acute inflammatory reaction.

194

What may precipitate gout?

Alcohol or consumption of meat may precipitate arthritis.

195

What does chronic gout lead to?

1) development of tophi 2) renal failure

196

In gout, what happens in the development of tophi?

white, chalky aggregates of uric acid crystals with fibrosis and giant cell reaction in the soft tissue and joints

197

In gout, why is there renal failure?

Urate crystals may deposit in kidney tubules (urate nephropathy).

198

What are the laboratory findings for gout?

include hyperuricemia; synovial fluid shows needle-shaped crystals with negative birefringence under polarized light

199

What is pseudogout?

It resembles gout clinically, but is due to deposition of calcium pyrophosphate dihydrate (CPPD); synovial fluid shows rhomboid-shaped crystals with weakly positive birefringence under polarized light

200

What is dermatomyositis?

Inflammatory disorder of the skin and skeletal muscle

201

What is the etiology for dermatomyositis?

some cases are associated with carcinoma (e.g., gastric carcinoma)

202

What are the clinical features for dermatomyositis?

1) Bilateral proximal muscle weakness; distal involvement can develop late in disease. 2) Rash of the upper eyelids (heliotrope rash); malar rash may also be seen. 3) Red papules on the elbows, knuckles, and knees (Grotton lesion)

203

What are the laboratory findings for dermatomyositis?

1) Increased creatinine kinase 2) Positive ANA and anti-Jo-l antibody 3. Perimysial inflammation (CD4+ T cells) with peritascicular atrophy on biopsy

204

For dermatomyositis, what is seen on biopsy?

Peritascicular atrophy

205

What is the treatment for dermatomyositis?

corticosteroids.

206

What is polymyositis?

Inflammatory disorder of skeletal muscle

207

What does polymositis resemble?

dermatomyositis clinically, but skin is not involved

208

For polymositis, what is seen on biopsy?

endomysial inflammation (CD8+ T cells) with necrotic muscle fibers is seen on biopsy

209

What is x-linked muscular dystrophy?

Degenerative disorder characterized by muscle wasting and replacement of skeletal muscle by adipose tissue

210

What is x-linked muscular dystrophy due to?

mutations of dystrophin

211

What is dystrophin?

it is important for anchoring the muscle cytoskeleton to the extracellular matrix.

212

Describe the mutations for x-linked muscular dystrophy?

They are often spontaneous; large gene size predisposes to high rate of mutation.

213

What is Duchenne muscular dystrophy?

it is due to deletion of dystrophin

214

How does Duchenne muscular dystrophy present?

as proximal muscle weakness at 1 year of age; progresses to involve distal muscles

215

What is a characteristic of Duchenne muscular dystrophy?

Calf pseudohypertrophy

216

What enzyme is elevated in Duchenne muscular dystrophy?

Serum creatinine kinase

217

In Duchenne muscular dystrophy what does death result from?

cardiac or respiratory failure; myocardium is commonly involved.

218

What is Becker muscular dystrophy due to?

mutated dystrophin

219

What does Becker muscular dystrophy clinically result in?

milder disease than Duchenne muscular dystrophy

220

What is myasthenia gravis?

Autoantibodies against the postsynaptic acetylcholine receptor at the neuromuscular junction

221

In whom is myasthenia gravis more commonly seen?

in women

222

What are the clinical features for myasthenia gravis?

1) Muscle weakness that worsens with use and improves with rest; classically involves the eyes, leading to ptosis and diplopia 2) Symptoms improve with anticholinesterase agents. 3) Associated with thymic hyperplasia or thymoma; thymectomy improves symptoms.

223

In myasthenia gravis, what does the muscle weakness lead to?

Ptosis and diplopia

224

What does the symptoms of myasthenia gravis improve with?

Anticholinesterase agents

225

What is myasthenia gravis associated with?

Thymic hyperplasia or thymoma; thymectomy improves symptoms

226

What is Lambert-eaton syndrome?

Antibodies against presynaptic calcium channels of the neuromuscular junction

227

What does Lambert-eaton syndrome arise as?

a paraneoplastic syndrome,

228

What is Lambert-eaton syndrome most commonly due to?

small cell carcinoma of the lung

229

What does Lambert-eaton syndrome leads to?

impaired acetylcholine release

230

In Lambert-eaton syndrome the impaired acetylcholine release causes what in the neuromuscular junction?

The firing of presynaptic calcium channels is required for acetylcholine release

231

What are the clinical features for Lambert-eaton syndrome?

1. Proximal muscle weakness that improves with use; eyes 3re usually spared. 2. Anticholinesterase agents do not improve symptoms. 3. Resolves with resection of the cancer

232

What is a lipoma?

Benign tumor of adipose tissue

233

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

lipoma

234

What is a liposarcoma?

Malignant tumor of adipose tissue

235

What is the most common malignant soft tissue tumor in adults?

liposarcoma

236

What is the characteristic cell for liposarcoma?

Lipoblast

237

What is rhabdomyoma?

Benign tumor of skeletal muscle

238

What is cardiac rhabdomyoma associated with?

tuberous sclerosis

239

What is rhabdomyosarcoma?

Malignant tumor of skeletal muscle

240

What is the most common malignant soft tissue tumor in children?

rhabdomyosarcoma

241

What is the characteristic cell for rhabdomyosarcoma?

Rhabdomyoblast

242

Rhabdomyosarcoma is positive for what?

desmin positive

243

What is the most common site for rhabdomyosarcoma?

it is the head and neck

244

What is the classic site for rhabdomyosarcoma for young girls?

vagina