Inflammatory Myopathies

Question 1

Dermatomyositis, polymyositis, and inclusion body myositis are all examples of ___.

Answer 1

inflammatory myopathies

Question 2

How common are inflammatory myopathies?

Answer 2

Uncommon, 1 in 100,000 annually

Question 3

Are inflammatory myopathies suppurative?

Answer 3

Nonsuppurative inflammation

Question 4

Inflammatory myopathies have what four characteristics?

Answer 4

1. Presence of inflammatory cells
2. Necrosis and phagocytosis of muscle fibers
3. A mixture of regenerating and atrophic fibers
4. Fibrosis

Question 5

Which muscles commonly experience weakness with inflammatory myopathies?

Answer 5

Symmetrical proximal muscles (shoulders, hips, torso) (can eventually go distal)

Question 6

How do inflammatory myopathy symptoms progress over time?

Answer 6

• Gradually increasing symptoms over weeks or months
• Progressive difficulties with activities of daily living (lifting object, climbing stairs, combing hair, holding head up)

Question 7

Inflammatory myopathy lab results show increased levels of:

Answer 7

• serum muscle-derived enzymes
• ESR
• (maybe) C-reactive protein

Question 8

Inflammatory myopathies are commonly comorbid with ___.

Answer 8

other autoimmune conditions (antibodies tested to determine which)

Question 9

How are inflammatory myopathies generally treated?

Answer 9

• Corticosteroids
• Immunosuppressant drugs (DMARDs)
• IV immunoglobulin

Question 10

Which inflammatory myopathy has no effective therapy?

Answer 10

Inclusion body myositis

Question 11

Does dermatomyositis more often affect children or adults?

Answer 11

Adults

Question 12

Which sex is more often affected by dermatomyositis?

Answer 12

Females

Question 13

Dermatomyositis is likely comorbid with ___.

Answer 13

systemic sclerosis or other autoimmune disorders

Question 14

A 22-year-old female presents with a rash on her upper eyelids, face, trunk, and some other areas where the sun hits. It is known that she has systemic sclerosis, but now there is evidence of necrosis of skeletal muscle tissue and fiber atrophy.
What is the likely diagnosis?

Answer 14

Dermatomyositis

Question 15

A 30-year-old female complains of progressive difficulty performing physical tasks over the past four months. She has a bit of a rash on her face which she says is also on her shoulders. She also reports difficulty swallowing solids recently. Lab tests reveal an elevated ESR and presence of serum muscle-derived enzymes.
What is the likely diagnosis?

Answer 15

Dermatomyositis

Question 16

What is the etiology of dermatomyositis?

Answer 16

Autoimmune

there is no one explanation

Question 17

With dermatomyositis, compliment mediated (humoral immunity) antibodies attack ___ of skeletal muscle.

Answer 17

microvasculature

angiopathy, microangiopathy

this is not vasculitis/inflammation, it’s break down

Question 18

With dermatomyositis, ___ attack microvasculature of skeletal muscle (angiopathy).

Answer 18

compliment mediated antibodies (humoral immunity)

Question 19

Dermatomyositis involves ischemia of ___ which leads to ___ and ___.

Answer 19

ischemia of individual muscle fibers which leads to necrosis of skeletal muscle tissue and fiber atrophy

Question 20

When dermatomyositis is causing ischemia of individual muscle fibers, necrosis of that skeletal muscle tissue, and fiber atrophy will occur.
Which muscles are often first to be affected?

Answer 20

Gluteal muscles

Question 21

Why might infarcts occur with dermatomyositits?

Answer 21

Due to involvement of large intramuscular arteries

Question 22

How might dermatomyositis affect structures other than muscle?

Answer 22

Similar process will affect other other tissues and organs
e.g. difficulty swallowing solids due to diaphragm damage

diaphragm would cause mechanical/muscular dysphagia

Question 23

What is the etiology of polymyositis?

Answer 23

Autoimmune

Question 24

Polymyositis almost always begins after age ___.

Answer 24

20

Question 25

Which sex is predominantly affected by polymyositis?

Answer 25

Females

Question 26

Does polymyositis involve a skin rash?

Answer 26

No

Question 27

Does polymyositis involve angiopathy?

Answer 27

No

Question 28

With polymyositis, ___ directly attack muscle fibers.

Answer 28

T cells

Question 29

What is represented histologically in polymyositis?

Answer 29

* Necrosis * Phagocytosis (macrophages present) * Regeneration * Fibrosis

Question 30

Does polymyositis progress systemically or locally?

Answer 30

Systemic progression

Question 31

Polymyositis has similar muscle inflammation as that seen in ___ infection.

Answer 31

HIV

Question 32

What is the nature of degeneration associated with polymyositis?

Answer 32

Degeneration is scattered, and not always in the areas of inflammation

Question 33

Will polymyositis first present more proximally or distally?

Answer 33

Proximally

Question 34

A 28-year-old female presents with her primary complaint being progressive muscle weakness and diffuse pain in both shoulders. Upon examination, there is evidence of weakness in both of her hips as well. Suspecting this may be systemic, she is sent for lab testing which reveals an elevated ESR and presence of serum muscle-derived enzymes. What is the likely diagnosis?

Answer 34

Polymyositis | no rash mentioned

Question 35

Polymyositis is the same as dermatomyositis without the presentation of ___.

Answer 35

rash

Question 36

What is the most common inflammatory myopathy in geriatrics?

Answer 36

Inclusion body myositis

Question 37

Inclusion body myositis most commonly presents at what age?

Answer 37

Over age 50

Question 38

Which sex is predominantly affected by inclusion body myositis?

Answer 38

Males

Question 39

Inclusion body myositis involves the presence of specific antigen on ___.

Answer 39

sarcolemma

Question 40

How are T cells related to inclusion body myositis? What is this similar to?

Answer 40

T cells attack skeletal muscle fiber; similarly to polymyositis

Question 41

Inclusion body myositis histologically shows ___ in the ___ of involved muscle fibers and near ___.

Answer 41

**basophilic granular inclusions** in the **cytoplasm or nuclei** of involved muscle fibers and near **vacuoles**

Question 42

Inclusion body myositis primarily involves which regions of the body?

Answer 42

**Distal muscles**: hands and feet

Question 43

A 55-year-old male presents with atrophy of skeletal muscle tissue in his hands. Upon biopsy, the involved muscle fibers show basophilic granular inclusions containing intracellular B-amyloid plaque throughout the cytoplasm and nuclei. What is the diagnosis?

Answer 43

Inclusion body myositis

Question 44

What is found in the basophilic inclusions of muscles affected by inclusion body myositis?

Answer 44

* B-amyloid plaque * Tau proteins and other proteins associated with Alzheimer present * Parkin (associated with Parkinson disease) and the prion precursor protein have also been found

Question 45

What are the ESR and CRP levels in someone with inclusion body myositis?

Answer 45

Elevated

Question 46

How does inclusion body myositis respond to therapy?

Answer 46

Poorly