Inflammatory myopathy is a systemic autoimmune disorder characterized by muscle inflammation, weakness, and potential internal organ involvement, with main types including polymyositis and dermatomyositis. These conditions often have varying manifestations, such as skin rashes, muscle enzyme elevation, and can lead to complications like interstitial lung disease. Factors such as gender, age, and specific antibodies (e.g., anti-jo1) influence severity, prognosis, and associated risks like malignancy.

1. Inflammatory Myositis
MSA and associated
manifestation
Dr. Abeer Alhalwani
Rheumatology F1

4. The inflammatory myopathy is a systemic autoimmune rheumatic
disorder that characterized by chronic muscle inflammation, muscle
weakness, fatigue and internal organ involvement.
The four main types of chronic inflammatory myopathies are:
-polymyositis
-dermatomyositis
-inclusion body myositis
-necrotizing autoimmune myopathy

5. is approximately 2 to 8 cases per million
people each year.
-For unknown reasons, polymyositis and
dermatomyositis are about twice as common
in women as in men,
while sporadic inclusion body myositis is more
common in men.

6. DM :
-It is a cell-mediated immunity in which CD4 T
lymphocytes bind to endothelial cells followed
by activation of the complement system
-Damage to the capillary and tissue hypoxia
-Perifasicular atrophy

7. PM and IBM:
-Indomysial infiltration with CD8 T lymphocytes
invade non-necrotic muscle fibers
-MHC class 1 overexpression
-Endoplasmic reticulum stress
-Myofiber damage

8. Pathognomonic:
heliotrope rash, Edema of eyelid, Gottron's sign, Gottron's
papules,
Characteristic:
Shawl sign, nail-fold bleeding, scalp scaly disease, photosensitive
poikiloderma
Occasional:
Erythema (holster sign), calsinosis, skin ulcer, cutaneous
vasculitis.

9. skin ulcer,
cutaneous vasculitis and
bullous rash

11. Variable prevalence 18-53%
Overlap syndrome
Low prevalence in cancer associated and
IBM
Some patients had joint symptoms prior to
weakness

12. most common : symmetrical polyarthritis
non-erosive (erosion: overlap)
Floppy thumb: calcinosis at the tendons
resulting in joint subluxation, associated with
anti-Jo1.

13. most commonly associated with anti-
synthetase antibody (Jo1)
seen in anti-MDA5
PM-Scl

15. Associated with worse outcome
Anti-Synthetase syndrome:
most common is Anti-Jo1
Anti-PL12 more severe ILD
Anti-PL7 higher rate of RPILD
Anti-MDA5:
acute onset and RPILD
Poor outcome

16. Anti-Ro/Jo1 overlap: higher rates for ILD
Anti Ro: more severe ILD
Low rates of ILD:
Anti SRP
Anti Mi2
Anti TIF1
Anti NXP-2

17. Types of ILD:
NSIP (most common)
organizing Pneumonia
UIP
diffuse alviolar damage
unclassified
Anti-synthetase: GGO and reticulation are the most common findings.
Typical distribution: basal, peripheral and peribronchovascular.

19. Hypomyopathic/Amyopathic dermatomyositis
Palmar erythematous papules
cutaneous/oral ulcers
cutaneous necrosis
gum pain

20. Myocarditis reported
Can have elevated muscle enzymes with no
weakness
ILD can be severe and fulminant (RPILD)
Presence of pneumomediastinum > worse
prognosis

21. Can present as:
ILD without myositis (32%)
Isolated myositis (26%)
ILD with myositis (22%)
Isolated arthritis (17%)

22. Rapid and severe weakness
Dysphagia , Very high muscle enzymes ,Cardiomyopathy
Associated with:
Anti-SRP
Anti HMGCR
Malignancy
Histology:
Myofiber necrosis, Phagocytosis by Macrophage, Complement binding in sarcolemma
Resistant to treatment

23. Classic presentation with rash (can precede
the weakness)
Low incidence of ILD and cardiac
involvement
Low risk of malignancy
Well response to treatment

24. prevalent in males (2-3:1)
Insidious Asymmetric weakness in proximal legs and distal arms
(hip flexor and finger flexor)
Sparing thinner, hypothenar and finger extensors
Facial weakness (55%)
Dysphagia
No pulmonary or cardiac involvement
No risk of malignancy

25. Neuropathic findings can be present (misdiagnosed as
ALS)
Histopathology:
Endomysial infiltrates
Cytoplasmic inclusions
Rimmed vacuoles
Can be associated with Anti-cN1A

26. Higher risk:
-DM compared to PM
-male compared to females
-elder compared to younger Pt
Anti-TIF1:
-Associated with malignancy in 75% of cases in adults
-Severe skin disease
-Less likely to have ILD, arthritis and raynaud
Anti-NXP2:
-Calsinosis

27. Anti PM/Scl in Myositis-Systemic sclerosis
overlap
Anti U-1 RNP in MCTD which can have
myositis
Anti-Ku in association of SLE, SSc or UCTD
overlapping with myositis
ILD is common

30. A- Anti-Ro
B- Anti-TIF1
C- Anti-PL7
D- Anti-U1RNP

31. A- ILD
B- Muscle weakness
C- Raynaud Phenomenon
D- Arthritis

32. A- male gender
B- severe skin manifestation
C- Arthritis
D- Calcinosis

33. Rheumatology secret
Uptodate
www.rheumatology.medicinematters.com
www.myositis.org