18.4 Skeletal muscles and Neuromuscular stuff

Question 1

What, generally, is dermatomyositis?

Answer 1

Idiopathic Inflammatory disorder of the skin and skeletal muscle

Question 2

What is usually associated with dermatomyositis?

Answer 2

GI malignancies

Question 3

What are the muscular features of dermatomyositis?

Answer 3

• Bilateral proximal muscle weakness

- Distal involvement later in dz course

Question 4

What are the skin features of dermatomyositis?

Answer 4

• Rash of the upper eyelids (heliotrope rash)

- Red papules on the elbows, knuckles, and knees

Question 5

Malar rash + bilateral proximal muscle weakness = ?

Answer 5

Dermatomyositis

Question 6

What enzyme is classically elevated with dermatomyositis?

Answer 6

CK

Question 7

What are the antibodies that are found with dermatomyositis?

Answer 7

ANA

Anti-Jo-1

Question 8

What are the immune cells that cause the destruction in dermatomyositis? Where is the inflammation seen histologically?

Answer 8

CD4+ T cells

Perimysial inflammation

Question 9

What is the treatment for dermatomyositis?

Answer 9

Corticosteroids

Question 10

ANA +, malar rash, and Anti- Jo-1 = ?

Answer 10

Dermatomyositis

Question 11

What is the CT layer that surrounds a single fascicle? Multiple?

Answer 11

Single = perimysium
Multiple = Epimysium

(endomysium surrounds muscle fibers)

Question 12

What, generally, is polymyositis? How does it compare to dermatomyositis?

Answer 12

Inflammatory disorder of the skeletal muscle that resembles dermatomyositis, but lacks skin involvement

Question 13

What part of the muscles is inflamed with polymyositis? What are the immune cells that cause this?

Answer 13

Endomysial inflammation by CD8+ T cells

Question 14

Match: (endomysial/ perimysial inflammation); (polymyositis/ dermatomyositis)

Answer 14

• Polymyositis = endomysial

- Dermatomyositis = perimysial

Question 15

What is the inheritance pattern of muscular dystrophies? What is the genetic defect with this?

Answer 15

• XLR

- Deletions of dystrophin gene (for for Duchenne)

Question 16

What is the pathological process that characterizes muscular dystrophy?

Answer 16

Replacement of skeletal muscles by adipose tissue

Question 17

What is the function of dystrophin protein?

Answer 17

Anchors muscle cytoskeleton to the extracellular matrix

Question 18

Why is muscular dystrophy often a spontaneous, as opposed to an inherited one?

Answer 18

Dystrophin gene is one of the largest in the human genome, and thus is more susceptible to damage

Question 19

What is the genetic defect in Becker’s vs Duchenne’s muscular dystrophy?

Answer 19

Beckers = mutation
Duchennes = deletion

Question 20

How do kids with Duchenne muscular dystrophy usually present?

Answer 20

Proximal muscle weakness before 1 year of age

Question 21

What is the classic feature of Duchenne muscular dystrophy?

Answer 21

Calf pseudohypertrophy (2/2 fat deposition)

Question 22

What is the enzyme that is elevated with Duchenne muscular dystrophy?

Answer 22

CK

Question 23

What usually causes death with Duchenne muscular dystrophy?

Answer 23

Cardiac or respiratory failure

Question 24

What part of the heart is involved with Duchenne muscular dystrophy?

Answer 24

Myocardium

Question 25

Why is MG characterized by fatigable muscles?

Answer 25

Each time contraction occurs, less ACh is able to be release and compete with anti-nicotinic abs

Question 26

Are the antibodies with MG competitive or noncompetitive for ACh receptors?

Answer 26

Competitive

Question 27

Which gender is more commonly affected with MG?

Answer 27

Women

Question 28

What part of the body is classically affected with MG?

Answer 28

Eyes--ptosis and diplopia

Question 29

What is MG classically associated with and can be seen on CXR?

Answer 29

Thymic hyperplasia or thymoma

Question 30

What malignancy is classically associated with Lambert-Eaton syndrome?

Answer 30

small cell lung cancer

Question 31

Why does muscle strength improve with Eaton-Lambert syndrome?

Answer 31

Keep trying to force Ca in competes with antibody

Question 32

True or false: the eyes are classically affected with Eaton-Lambert syndrome

Answer 32

False-- spared. MG is classically affected

Question 33

How do you differentiate MG and Eaton-Lambert syndrome clinically, besides history?

Answer 33

Anticholinesterase agents do not improve symptoms

Question 34

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

Answer 34

Lipomas

Question 35

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

Answer 35

Liposarcomas

Question 36

What is the characteristic cell of liposarcomas?

Answer 36

Lipoblasts

Question 37

What is cardiac rhabdomyomas usually seen with?

Answer 37

Tuberous sclerosis

Question 38

What, generally, is a rhabdomyoma?

Answer 38

Benign tumor of skeletal muscle

Question 39

What, generally, is a rhabdomyosarcoma?

Answer 39

Malignant tumor of skeletal muscle

Question 40

What is the characteristic cell of rhabdomyosarcomas?

Answer 40

Rhabdomyoblast

Question 41

What is the most common site of a rhabdomyosarcoma? What is the classic presentation in young girls?

Answer 41

Head and neck most common Vagina in young girls

Question 42

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

Answer 42

Rhabdomyosarcoma

Question 43

What is the stain that highlights rhabdomyosarcomas?

Answer 43

Desmin

Question 44

Young girl with a grape-like mass protruding from the vagina = ?

Answer 44

Rhabdomyosarcoma