3.2.2 Muscle Pathology I

Question 1

What are the characteristics of Dermatomyositis?

Answer 1

Proximal weakness

Rash - over 90% of the time

Complement deposition in capillaries

PERIVASCULAR INFLAMMATION - PERIMYSIUM

Associated with cancer - must screen individuals for cancers

Question 2

What are some of the clinical features of the muscular dystrophy diseases?

Answer 2

Pelvic girdle weakness

Pseudohypertrophy of calf muscles

Initial CK increase and later decrease.

Question 3

What determines whether a muscle cell will be a type 1 or type 2 muscle fiber?

Answer 3

The motor neuron

Question 4

What is this an image of?

Answer 4

Neurogenic atrophy

Many nuclear clumps (end-stage fibers) seen as well as some endomysial fibrous tissue increase.

These are diseases like - ALS, vasculitis, trauma, nerve compression.

Question 6

What is this an image of?

Answer 6

Muscular dystrophy

Endomysial fibrosis, regeneration, sometimes lymphocytes, rounded fibers, hypertrophic and smaller fibers can be seen.

Question 7

Compare the Type 1 and 2 muscle fiber :

Action

Strength

Lipids

Glycogen

Physiology

Color

Answer 7

Question 8

What is this an image of?

Answer 8

Inclusion body myositis with abnormal fiber with vacuoles

Question 9

What are these images indicative of?

Answer 9

Dermatomyositis

Facial rash and perivascular inflammation

Question 10

What are the characteristics of Inclusion Body Myositis?

Answer 10

Question 11

What is this an image of?

Answer 11

Skeletal muscle - note the abundance of fat

Question 12

What are the characteristics of Polymyositis?

Answer 12

Proximal weakness w/o skin involvement

ENDOMYSIAL PROCESS

Question 13

Describe the pathological findings of Inclusion Body Myositis.

Answer 13

Inflammation and fibrosis

Intracytoplasmic vacuoles surrounded by basophilic granules: RED ON TRICHROME = RIMMED VACUOLES

Question 14

What is this an image of?

Answer 14

Oil Red O stain for fat

Question 15

What is this an image of?

Answer 15

Dermatomyositis

Perifascicular pattern of injury

Question 16

Describe the inclusions in IBM.

Answer 16

Question 17

What are some general features that might lead one to believe there is a myopathy?

Answer 17

Fiber size variability

Fiber splitting

Degeneration/regeneration (basophilia)

Increased centralized nuclei

Question 18

What is found in these capillaries in regards to dermatomyositis?

Answer 18

Membrane attack complex. Dermatomyositis has abnormal activation of MAC

Question 19

What is the difference between these two images?

Answer 19

Left - Normal staining with dystrophin

Right - Duchenne MD with dystrophin staining

Question 20

What is this an image of?

Answer 20

Dermatomyositis

Perifascicular pattern of injury - cells on the outside are smaller than the cells on the inside

Question 21

What is being stained dark and what is being stained light?

Answer 21

Dark - Type 2 fibers

Light - Type 1 fibers

Question 22

What type of stain is this?

Answer 22

PAS stain for glycogen

Question 23

What is this an image of?

Answer 23

Inclusion body myositis

Gomori trichrome showing rimmed vacuoles.

Question 24

What are some of the characterisitcs of neurogenic atrophy?

Answer 24

Disease of the anterior horn cell or its axon

Initial - individuals atrophic angular fibers

Later - groups of atrophic angular fibers