PATHOMA18 - Musculoskeletal Pathology Flashcards
(247 cards)
1
Q
What is achondroplasia?
A
Impaired cartilage proliferation in the growth plate
2
Q
What is achondroplasia a common cause of?
A
dwarfism
Short extremities with normal-sized head and chest
3
Q
What is achondroplasia due to?
A
an activating mutation in fibroblast growth factor receptor 3 (FGFR3) Autosomal dominant
4
Q
What does the overexpression of FGFR3 do?
A
It inhibits cartilage growth (and therefore inhibits bone growth)
5
Q
What are most mutations for achondroplasia?
A
they are sporadic and related to increased paternal age.
6
Q
In achondroplasia, why is there short extremities with normal-sized head and chest?
A
its due to poor endochondral bone formation; intramembranous bone formation is not affected.
7
Q
How is endochondral bone formation characterized?
A
by formation of a cartilage matrix, which is then replaced by bone; it is the mechanism by which long bones grow.
8
Q
How is intramembranous bone formation characterized?
A
by formation of bone without a preexisting cartilage matrix; it is the mechanism by which fiat bones (e.g., skull and rib cage) develop.
9
Q
TRUE/ FALSE:
Mental function, life span, and fertility are not affected in achondroplasia
A
TRUE
10
Q
What is osteogenesis imperfecta?
A
It?s a congenital defect of bone resorption resulting in structurally weak bone
11
Q
What is osteogenesis imperfecta most commonly due to?
A
an autosomal dominant defect in collagen type 1 synthesis
12
Q
What is blue sclera?
A
thinning of scleral collagen reveals underlying choroidal veins.
13
Q
What are the clinical features for osteogenesis imperfecta?
A
1) Multiple fractures of bone (can mimic child abuse, but bruising is absent) 2) blue sclera?3) Hearing loss
14
Q
Why is there hearing loss in osteogenesis imperfecta?
A
Bones of the middle ear easily fracture
15
Q
What is Osteopetrosis ?
A
inherited defect of bone resorption resulting in abnormally thick, heavy bone that fractures easily
16
Q
What is Osteoporosis Due to?
A
Its due to high/longer Osteoclast function
17
Q
What is an example for the multiple genetic variants that exist for Osteopetrosis?
A
carbonic anhydrase II mutation leads to loss of the acidic microenvironment required for bone resorption
18
Q
In osteoporosis, why is there anemia in Osteopetrosis?
A
It is due to bony replacement of the marrow (myelophthisic process)
19
Q
What are the clinical features for Osteopetrosis?
A
1) Bone fractures 2) Anemia, thrombocytopenia, and leukopenia with extramedullar hematopoiesis 3) Vision and hearing impairment 4) hydrocephalus 5) renal tubular acidosis
20
Q
In Osteopetrosis, why is there vision and hearing impairment?
A
due to impingement on cranial nerves
21
Q
In Osteopetrosis, why is there renal tubular acidosis?
A
Its seen with carbonic anhydrase II mutation, a lack of carbonic anhydrase results in decreased tubular reabsorption of HCO3 leading to metabolic acidosis.
22
Q
What is the treatment for Osteopetrosis?
A
It is bone marrow transplant; osteoclasts are derived from monocytes.
23
Q
What causes Ricketts and osteomalacia
A
Defective mineralization of osteoid
24
Q
What do osteoblasts normally produce?
A
Osteoid which is then mineralized with calcium and phosphate to form bone
25
What are Rickets and osteomalacia due to?
low levels of vitamin D, which results in low serum calcium and phosphate
26
What is vitamin D normally derived from?
the skin upon exposure to sunlight (85%) and from the diet (15%).
27
What does activation of Vitamin D require?
25-hydroxylation by the liver followed by 1-alphahydroxylatton by the proximal tubule cells of the kidney
28
What does active vitamin D do?
it raises serum calcium and phosphate
29
How does active Vitamin D raise serum calcium and phosphate?
by acting on the intestines, kidney and bone
30
What is the effect of active Vitamin D on the intestine?
It increases absorption of calcium and phosphate
31
What is the effect of active vitamin D on the kidney?
it increases reabsorption of calcium and phosphate
32
What is the effect of active vitamin D on bone?
It increases resorption of calcium and phosphate
33
In whom is vitamin D deficiency seen?
with decreased sun exposure (e.g.. northern latitudes), poor diet, malabsorption, liver failure, and renal failure.
34
What is Rickets due to?
due to low vitamin D in children, resulting in abnormal bone mineralization.
35
In whom does Rickets most commonly arise?
in children \< 1 year of age
36
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
37
What is pigeon-breast deformity in Rickets?
It?s inward bending of the ribs with anterior protrusion of the sternum
38
What is the frontal bossing in Rickets due to?
The enlarged forehead is due to osteoid deposition on the skull
39
What is Rachitic rosary due to?
osteoid deposition at the costochondral junction
40
What is osteomalacia due to?
low vitamin D in adults.
41
What is seen in ostomalacia?
Inadequate mineralization which results in weak bone with an increased risk for fracture.
42
What are the laboratory findings for osteomalacia?
decreased serum calcium, decreased serum phosphate, increased PTH, and increased alkaline phosphatase
43
What is osteoporosis?
It?s a reduction in trabecular bone mass
44
What does osteoporosis result in?
porous bone with an increased risk for fracture
45
What is the risk of osteoporosis based on?
peak bone mass (attained in early adulthood) and rate of bone loss that follows thereafter
46
When is peak bone mass achieved?
by 30 years of age
47
What is peak bone mass based on?
it is based on (1) genetics (eg vitamin D receptor variants), (2) diet, and (3) exercise.
48
What happens to bone mass after age 30?
slightly less than 1% of bone mass is lost each year
49
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).
50
What are the most common forms of osteoporosis?
They are senile and postmenopausal.
51
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).
52
What must be excluded when osteoporosis is suspected? How is this done?
Osteomalacia and the labs help to exclude it
53
How is bone density measured?
using a DEXA scan
54
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).
55
What is paget disease of bone due to?
Imbalance between osteoclast and osteoblast function
56
When is paget disease of bone usually seen?
in late adulthood (average age \> 60 years)
57
What is the etiology for Paget disease of bone?
It is unknown; possibly viral
58
Is Paget disease of bone localized or systemic?
It?s a localized process involving one or more bones; does not involve the entire skeleton
59
What are the three distinct stages of Paget disease of bone?
(1) osteoclastic, (2) mixed osteoblastic-osteoclastic, and (3) osteoblastic.
60
What is the end result for paget disease of bone?
it is thick, sclerotic bone that fractures easily
61
What does biopsy for Paget disease of bone reveal?
a mosaic pattern of lamellar bone
62
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
63
In Paget disease of bone, why is there bone pain?
Its due to microfractures
64
In Paget disease of bone why is there increasing hat size?
Skull is commonly affected.
65
In Paget disease of bone, why is there hearing loss?
impingement on cranial nerve
66
In Paget disease of bone, why is there lion-like facies?
involvement of craniofacial bones
67
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
68
What is the treatment for Paget disease of bone?
1) calcitonin 2) bisphosphonates
69
Why does calcitonin help in Paget disease of bone?
It inhibits osteoclast function
70
Why does bisphosphonates help in Paget disease of bone?
It induces apoptosis of osteoclasts
71
What are the complications for Paget disease of bone?
1) High-output cardiac failure?due to formation of AV shunts in bone 2) Osteosarcoma
72
Why is there high-output cardiac failure as a complication for Paget disease of bone?
Its due to formation of AV shunts in bone
73
What is osteomyelitis?
Infection of marrow and bone
74
In whom does osteomyelitis usually occur?
in children
75
What type of infection is most commonly involved in osteomyelitis?
bacterial
76
In osteomyelitis, why would it most commonly arise?
It arises via hematogenous spread
77
What happens in osteomyelitis in children?
Transient bacteremia (children) seeds metaphysis.
78
What happens in osteomyelitis in adults?
Open-wound bacteremia (adults) seeds epiphysis.
79
What are the causes for osteomyelitis?
1) Staphylococcus 2) Gonorrhoeae 3) Salmonella 4) Pseudomonas 5) Pasteurella 6) Mycobacterium tuberculosis
80
What bacteria is the most common cause of osteomyelitis?
Staphylococcus aureus (90% of cases)
81
What is the cause of osteomyelitis in sexually active young adults?
gonorrhoeae
82
What is the cause of osteomyelitis in sickle cell disease patients?
Salmonella
83
What is the cause of osteomyelitis in diabetics or IV drug abusers?
Pseudomonas
84
What is the cause of ostoemyelitis in associated with cat or dog bite/scratches
pasteurella
85
What is the cause of ostoemyelitis in that usually involves vertebrae (Pott disease)?
mycobacterium tuberculosis
86
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
87
What is the lytic focus in osteomyelitis called?
Sequestrum
88
What is the sclerosis in osteomyelitis called?
involucrum
89
How is the diagnosis for osteomyelitis made?
by blood culture.
90
What is avascular (aseptic) necrosis?
Ischemic necrosis of bone and bone marrow
91
What are the causes for avascular (aseptic) necrosis?
trauma or fracture (most common), steroids, sickle cell anemia, and caisson disease.
92
What are major complications for avascular (aseptic) necrosis?
osteoarthritis and fracture are major complications.
93
What are the bone tumors?
Osteoma, osteoid osteoma, osteochondroma, osteosarcoma, giant cell tumor, ewing sarcoma, chondroma, chondrosarcoma, metastatic tumors
94
What is osteoma?
Benign tumor of bone
95
Where does osteoma most commonly arise?
arises on the surface of facial bones
96
What is osteoma associated with?
Gardner syndrome
97
What is osteoid osteoma?
Benign tumor of osteoblasts (that produce osteoid) surrounded by a rim of reactive bone
98
In whom does osteoid osteoma occur?
in young adults \< 25 years of age (more common in males)
99
Where does osteoid osteoma arise?
in cortex of long bones (e.g., femur)
100
How does osteoid osteoma present?
as bone pain that resolves with aspirin
101
In osteoid osteoma, what does imaging reveal?
a bony mass (\< 2 cm) with a radiolucent core (osteoid)
102
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
103
What is osteochondroma?
It is a tumor of bone with an overlying cartilage cap
104
What is the most common benign tumor of bone?
osteochondroma
105
How does osteochondroma arise?
from a lateral projection of the growth plate (metaphysis); bone is continuous with the marrow space.
106
Is there a connection between osteochondroma and cancer?
Overlying cartilage can transform (rarely) to chondrosarcoma.
107
What is osteosarcoma?
Malignant proliferation of osteoblasts
108
In whom is the Peak incidence for osteosarcoma seen?
in teenagers; less commonly seen in the elderly
109
What are the risk factors for osteosarcoma?
include familial retinoblastoma, Paget disease, and radiation exposure.
110
Where does osteosarcoma arise?
in the metaphysis of long bones, usually the distal femur or proximal tibia (region of the knee)
111
How does osteosarcoma present?
as a pathologic fracture or bone pain with swelling
112
What does imaging for osteosarcoma reveal?
a destructive mass with a sunburst appearance and lifting of the periosteum
113
What does biopsy for osteosarcoma reveal?
pleomorphic cells that produce osteoid
114
What is giant cell tumor?
Tumor comprised of multinucleated giant cells and stromal cells
115
In whom does giant cell tumors occur?
in young adults
116
Where do giant cell tumors arise?
in the epiphysis of long bones, usually the distal femur or proximal tibia (region of the knee)
117
In giant cell tumors, what is seen on x-ray?
Soap-bubble appearance on x-ray
118
Are giant cell tumors aggressive or benign?
its locally aggressive tumor; may recur
119
What is ewing sarcoma?
Malignant proliferation of poorly-differentiated cells derived from neuroectoderm
120
Where does ewing sarcoma arise?
in the diaphysis of long bones; usually in male children (\< 15 years of age)
121
For ewing sarcoma, what is the appearance on x-ray?
Onion-skin appearance on x-ray
122
What does biopsy for ewing sarcoma reveal?
small, round blue cells that resemble lymphocytes
123
What might ewing sarcoma be confused with?
lymphoma or chronic osteomyelitis
124
What translocation is characteristic of ewing sarcoma?
T(11;22)
125
How does ewing sarcoma often present?
with metastasis
126
Does ewing sarcoma respond to chemotherapy?
yes
127
What is chondroma?
Benign tumor of cartilage
128
Where does chondroma usually arise?
in the medulla of small bones of the hands and feet
129
What is chondrosarcoma?
Malignant cartilage-forming tumor
130
Where does chondrosarcoma arise?
in medulla of the pelvis or central skeleton
131
Which are more common, primary or metastatic tumors of the bone?
Metastatic tumors are more common than primary tumors
132
What do metastatic tumors usually result in?
osteolytic (punched-out) lesions
133
What classically produces osteoblastic lesions?
Prostatic carcinoma.
134
What is a joint?
Connection between two bones
135
How do joints provide structural strength?
Solid joints are tightly connected (eg cranial sutures)
136
What are synovial joints?
They have a joint space to allow for motion
137
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
138
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.
139
What is osteoarthritis?
Progressive degeneration of articular cartilage; most common type of arthritis
140
What is the most common type of arthritis?
osteoarthritis
141
What is osteoarthritis most often due to?
wear and tear
142
What is the major risk factor for osteoarthritis?
Age
143
In whom is osteoarthritis common?
after 60 years
144
In addition to age, what are some additional risk factors for osteoarthritis?
obesity and trauma.
145
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
146
What is the classic presentation for osteoarthritis?
joint stiffness in the morning that worsens during the day
147
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
148
What are Heherden nodes?
Osteophyte formation in distal interphalangeal joints
149
What are Bouchard nodes?
Osteophyte formation in proximal interphalangeal joints
150
What is rheumatoid arthritis?
Chronic, systemic autoimmune disease
Type IV hypersensitivity reaction
151
In whom does rheumatoid arthritis classically arise?
in women of late childbearing age
152
What is rheumatoid arthritis associated with?
HLA-DR4 and HLA-DR-1
(HLA = Human leukocyte antigen)
153
What is rheumatoid arthritis characterized by?
involvement of joints
154
What is the hallmark for rheumatoid arthritis?
synovitis leading to formation of a pannus (inflamed granulation tissue).
155
What does rheumatoid arthritis lead to?
destruction of cartilage and ankylosis (fusion) of the joint
156
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
157
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)
158
What is a difference between the arthritis seen in rheumatoid arthritis and osteoarthritis?
In rheumatoid arthritis the DIP is usually spared unlike osteoarthritis
159
For rheumatoid arthritis, what is seen on x-ray?
Joint-space narrowing, loss of cartilage, and osteopenia
160
What are rheumatoid nodules?
They are a central zone of necrosis surrounded by epithelioid histiocytes; arise in skin and visceral organs
161
What is vasculitis?
Multiple organs may be involved.
162
What is Baker cyst?
swelling of bursa behind the knee
163
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
2**. Anti-citrullinated protein/peptide antibodies (ACPA)** (measured via anti- CCP levels) have recently emerged as sensitive and specific serological markers of rheumatoid arthritis (RA), providing superior alternative of the rheumatoid factor (RF) test in the laboratory diagnostics of RA
164
What are the complications for rheumatoid arthritis?
1. anemia of chronic disease and secondary amyloidosis
2. Felty Syndrome (severe)
1. A rare subtype of rheumatoid arthritis (\< 1% of cases) characterized by arthritis, splenomegaly, and neutropenia. Usually occurs in the late stage of severe rheumatoid arthritis. The exact pathophysiology is not understood.
165
What are the seronegative spondyloarthropathies?
1) Ankylosing spondylarthritis 2) Reiter syndrome 3) Psoriatic arthritis
166
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
167
What does ankylosing spondylarthritis involve?
the sacroiliac joints and spine.
168
In whom does ankylosing spondylarthritis arise?
in young adults, most often male
169
How does ankylosing spondyloarthritis present?
with low back pain; involvement of vertebral bodies eventually arise leading to fusion of the vertebrae - bamboo spine
170
What are the extra-articular manifestations for ankylosing spondylarthritis?
They include uveitis and aortitis (leading to aortic regurgitation)
171
What is reiter syndrome characterized by?
the triad of arthritis, urethritis, and conjunctivitis.
172
In whom does Reiter syndrome arise?
in young adults (usually males) weeks after a GI or Chlamydia trachomatis infection
173
Psoriatic arthritis is seen in whom?
10% of cases of psoriasis.
174
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
175
What is infectious arthritis?
Arthritis due to an infectious agent, usually bacterial
176
What are the causes for infectious arthritis?
1) N. gonorrhoeae 2) S. aureus
177
What is the most common cause for infectious arthritis overall?
N. gonorrhoeae (its seen in young adults)
178
What is the 2nd most common cause of infectious arthritis overall?
S. aureus, and is seen in older children and adults
179
What does infectious arthritis classically involve?
It classically involves a single joint, usually the knee
180
What does infectious arthritis present as?
a warm joint with limited range of motion; fever, increased white count, and elevated ESR are often present
181
What is gout?
Deposition of monosodium urate (MSU) crystals in tissues, especially the joints
182
What is gout due to?
hyperuricemia; related to overproduction or decreased excretion of uric acid
183
Where is uric acid derived from?
purine metabolism
184
What excretes uric acid?
It is excreted by the kidney
185
What is the most common cause of gout?
Primary gout is the most common form;
186
What is the etiology of hyperuricemia?
it is unknown
187
What is secondary gout seen with?
1) Leukemia and myeloproliferative disorders 2) Lesch-Nyhan syndrome 3) Renal insufficiency
188
How does leukemia and myeloproliferative disorders lead to gout?
Increased cell turnover leads to hyperuricemia
189
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
190
How does renal insufficiency lead to gout?
decreased renal excretion of uric acid
191
How does gout present?
as exquisitely painful arthritis of the great toe (podagra)
192
Why does gout present as podagra?
1. MSU crystals deposit in the joint, triggering an acute inflammatory reaction.
193
What may precipitate gout?
Alcohol or consumption of meat may precipitate arthritis.
194
What does chronic gout lead to?
1) development of tophi 2) renal failure
195
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
196
In gout, why is there renal failure?
Urate crystals may deposit in kidney tubules (urate nephropathy).
197
What are the laboratory findings for gout?
include hyperuricemia; synovial fluid shows needle-shaped crystals with negative birefringence under polarized light
198
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
199
What is dermatomyositis?
Inflammatory disorder of the skin and skeletal muscle
200
What is the etiology for dermatomyositis?
some cases are associated with carcinoma (e.g., gastric carcinoma)
201
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)
202
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
203
For dermatomyositis, what is seen on biopsy?
Peritascicular atrophy
204
What is the treatment for dermatomyositis?
corticosteroids.
205
What is polymyositis?
Inflammatory disorder of skeletal muscle
206
What does polymositis resemble?
dermatomyositis clinically, but skin is not involved
207
For polymositis, what is seen on biopsy?
endomysial inflammation (CD8+ T cells) with necrotic muscle fibers is seen on biopsy
208
What is x-linked muscular dystrophy?
Degenerative disorder characterized by muscle wasting and replacement of skeletal muscle by adipose tissue
209
What is x-linked muscular dystrophy due to?
mutations of dystrophin
210
What is dystrophin?
it is important for anchoring the muscle cytoskeleton to the extracellular matrix.
211
Describe the mutations for x-linked muscular dystrophy?
They are often spontaneous; large gene size predisposes to high rate of mutation.
212
What is Duchenne muscular dystrophy?
it is due to deletion of dystrophin
213
How does Duchenne muscular dystrophy present?
as proximal muscle weakness at 1 year of age; progresses to involve distal muscles
214
What is a characteristic of Duchenne muscular dystrophy?
Calf pseudohypertrophy
215
What enzyme is elevated in Duchenne muscular dystrophy?
Serum creatinine kinase
216
In Duchenne muscular dystrophy what does death result from?
cardiac or respiratory failure; myocardium is commonly involved.
217
What is Becker muscular dystrophy due to?
mutated dystrophin
218
What does Becker muscular dystrophy clinically result in?
milder disease than Duchenne muscular dystrophy
219
What is myasthenia gravis?
Autoantibodies against the postsynaptic acetylcholine receptor at the neuromuscular junction
220
In whom is myasthenia gravis more commonly seen?
in women
221
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.
222
In myasthenia gravis, what does the muscle weakness lead to?
Ptosis and diplopia
223
What does the symptoms of myasthenia gravis improve with?
Anticholinesterase agents
224
What is myasthenia gravis associated with?
Thymic hyperplasia or thymoma; thymectomy improves symptoms
225
What is Lambert-eaton syndrome?
Antibodies against presynaptic calcium channels of the neuromuscular junction
226
What does Lambert-eaton syndrome arise as?
a paraneoplastic syndrome,
227
What is Lambert-eaton syndrome most commonly due to?
small cell carcinoma of the lung
228
What does Lambert-eaton syndrome leads to?
impaired acetylcholine release
229
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
230
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
231
What is a lipoma?
Benign tumor of adipose tissue
232
What is the most common benign soft tissue tumor in adults?
lipoma
233
What is a liposarcoma?
Malignant tumor of adipose tissue
234
What is the most common malignant soft tissue tumor in adults?
liposarcoma
235
What is the characteristic cell for liposarcoma?
Lipoblast
236
What is rhabdomyoma?
Benign tumor of skeletal muscle
237
What is cardiac rhabdomyoma associated with?
tuberous sclerosis
238
What is rhabdomyosarcoma?
Malignant tumor of skeletal muscle
239
What is the most common malignant soft tissue tumor in children?
rhabdomyosarcoma
240
What is the characteristic cell for rhabdomyosarcoma?
Rhabdomyoblast
241
Rhabdomyosarcoma is positive for what?
desmin positive
242
What is the most common site for rhabdomyosarcoma?
it is the head and neck
243
What is the classic site for rhabdomyosarcoma for young girls?
vagina
244
Histology of osteopytosis
245
What is Legg-Calve-Perthes Disease
a specific subtype of osteonecrosis --\> AVN of ossification centers (epiphyses) in children affecting femoral head ossification center
mn: Legg-Calve-Perthes --\>
Lil Child, Please --\> reminder that it affects children and is a disease of ossification centers
246
What is Osteochondritis Dessicans
a focal aseptic subtype of necrosis of subchondral bone in which a bone-cartilage fragment detaches and becomes displaced in the joint space. School-aged children and adolescents are most commonly affected. OD occurs as a result of overuse or trauma, and 75% of cases affect the knee --\> lateral surface of the medial femoral condyle
Symptoms include pain and **joint locking or catching.**
247
