Inflammatory Myopathy

Question 1

What is an inflammatory myopathy?

Answer 1

An autoimmune condition where the inflammatory response is directed against either normal muscle fibers alone or many tissues or against the supporting stroma

Question 2

What is the clinical presentation of polymyositis?

Answer 2

An inflammatory myopathy with symmetric, proximal greater than distal weakness with an onset that can be gradual or rapid

Question 3

What is the sex ratio of polymyositis?

Answer 3

Femal predominance

Question 4

What should be in the differential when evaluating for polymyositis?

Answer 4

If there is a lot of pain in joints and muscle: scleroderma, mixed connective tissue disease, lupus, rheumatoid arthritis (rarely)

If there is pulmonary involvement: sarcoidosis

Question 5

What is the pathology of polymyositis?

Answer 5

Inflammation around normal muscle fibers with other fibers that show necrosis/degeneration/regeneration, and nuclei located centrally (instead of peripherally)

Question 6

What lab tests should be done to evaluate polymyositis?

Answer 6

Sedimentation rate and anti Jo-1 antibody (as well as tests to evaluate for related systemic conditions)

Question 7

What is the treatment for polymyositis?

Answer 7

Corticosterioids either oral or IV once a week, can also use azathioprine, methotrexate, or cyclosporine.

Question 8

What is the clinical presentation of dermatomyositis?

Answer 8

Swallowing difficulty, persistent erythema in sun exposed skin, violaceous/edematous face and eyelids, eczema on extensor surfaces (MCP, elbows, knee, and sacrum)

Question 9

What symptoms are unique to juvenile dermatomyositis?

Answer 9

Toe walking due to ankle contractures and subcutaneous calcinosis

Question 10

What is the pathology of dermatomyositis?

Answer 10

Membrane attack complexes in capillaries, perivascular inflammation on a muscle biopsy, perifascicular atrophy

Question 11

What is the treatment for dermatomyositis?

Answer 11

Similar to polymyositis, cortiosteroids or alternative immunosuppressive agents

Question 12

What demographic groups are associated with inclusion body myositis?

Answer 12

Male predominance, older age predominance (except for familial variety)

Question 13

What are the clinical findings of inclusion body myositis?

Answer 13

Distal or asymmetric weakness, predilection for quadriceps more than hip muscles, particular wrist or finger flexor involvement. Disease has slow progression and leads to grip difficulty later in the course.

Question 14

What is the pathological hallmark of inclusion body myositis?

Answer 14

Rimmed vacuoles on H&E or gomori trichrome stain that are subsarcolemmal and stain with congo red. On EM, there are filaments with a beta amyloid appearance.

Question 15

What is the treatment for inclusion body myositis?

Answer 15

There isn’t any proven treatment. Glucorticosteroids do not work.

Question 16

What malignancies are associated with polymyositis or dermatomyositis?

Answer 16

Lung, ovary, breast, and GI cancers

Question 17

What is necrotizing myopathy?

Answer 17

It is not a myositis. It is an antibody mediated condition with a paucity of immune cells that can also be seen in cases of malignancy or as a paraneoplastic process.

Question 18

What condition is associated with the use of statin medications?

Answer 18

Necrotizing myopathy - some cases of necrotizing myopathy seem to be associated with antibodies against HMGCoA reductase, possibly resulting from statin use

Question 19

What is the pathology of necrotizing myopathy?

Answer 19

Scattered necrotic fibers without round cell infiltrate around normal fibers.

Question 20

What is fasciitis with peripheral eosinophilia?

Answer 20

A condition where there is necrotizing myopathy that affects the fascia more than the muscle and leads to thickened skin distally but without other scleroderma-like symptoms

Question 21

What is this pathology consistent with?

Answer 21

Polymyositis - immune infiltration and centralized nuclei

Question 22

What condition is the “shawl sign” related to?

Answer 22

Dermatomyositis - erythema on sun exposed surfaces

Question 23

What is this histology associated with?

Answer 23

Inclusion body myositis - apple green birifiriengence and congo red stain

Question 24

Asymmetrical or distal weakness would suggest:

a) PM
b) DM
c) IBM
d) any of the above

Answer 24

c) IBM

Question 25

The discovery of ovarian cancer 6 months into the development of weakness would suggest:

a) PM
b) DM
c) IBM
d) none of the above

Answer 25

a) PM or b) DM, both are tied to ovarian malignancies

Question 26

Which of the following medications is most commonly associated with a necrotizing myopathy?

a) azithromycin
b) simvastatin
c) gabapentin
d) tramadol

Answer 26

b) simvastatin

statins are linked to necrotizing myopathy

Question 27

Perifascicular atrophy is a hallmark of:

a) PM
b) DM
c) IBM
d) none of the above

Answer 27

b) DM - perifascicular atrophy is almost pathognomonic for DM