Polymyositis/dermatomyositis

Question 1

Lab values for polymyositis/dermatomyositis

Answer 1

Increased Creatinine Kinase
Increased LDH

Anti-nuclear antibodies

Highly specific for PM/DM
Jo-1, SRP, Mi-2
- against histidyl tRNA synthetase
- Signal Recogniction Particle

Question 2

Muscle biopsy findings for polymyositis and dermatomyositis

Answer 2

Polymyositis: CD8 T cells infiltrating the endomysium of muscle fibers.

Dermatomyosiotis: CD4 T cells infiltrating the perimyseium AND peri-Vascular area of muscles

Increased MHC 1 and CAM expression on muscle cells

Question 3

Typical patient age/gender of PM/DM, the idiopathic inflammatory myopathies (IIMs)

Answer 3

Equal male/female distribution of Polymyositis, 2:1 female/male for Dermatomyositis

PM: about 50 years old
DM: bimodal peaks, children 5-10 years, and adults about 50.

30% of DM patients will have occult malignancy

Question 4

Types of cancers associated with DM

Answer 4

Lung
Pancreas
GI
Ovarian

Question 5

Symptoms, presentation of PM and DM.

Answer 5

Symmetrical, progressive, proximal muscle weakness
Most often of the shoulders.

Further symptoms for dermatomyositis
1) Face and Shawl rash
2) Heliotrope lilac/purple coloration of the upper eyelids.
3) Gottron’s papules on the hands
Gottron’s knuckles, elbows, and knees plus increased CK = pathognomonic for Dermatomyositis and definite diagnosis.

Question 6

Treatment for PM/DM

Answer 6

Steroids to induce remission and long term DMARD-methorexate therapy

1st line: daily glucocorticoids

2nd line: Azathioprine, cyclosporine, MTX, IVIG, Plasma exchange.