Neuromuscular

IMMUNE MYOPATHIES WITH PERIMYSIAL PATHOLOGY (IMPP)

Clinical syndromes
  Dermatomyositis: Adult (variant) type
  Graft-vs-Host
  Myopathies with
    Anti-Jo-1 Antibodies
    Other tRNA synthetase antibodies
    High Aldolase & Normal CK
Dermatomyositis vs IMPP


IMPP: General

Clinical Features
  Immune myopathies: Similar to Jo-1 & tRNA synthetase antibody related immune myupathies

Pathology
  Perimysial damage: Prominent
  Probably same as: Dermatomyositis: Adult variant

Differences between IMPP and Dermatomyositis
  Both IMPP and Dermatomyositis have
    Muscle fiber pathology that is most prominent at the edge of fascicles
    Immune myopathy
  Some patients with IMPP have a Skin rash.
  However, there are distinctive differences between the syndromes

IMPP Dermatomyositis
CLINICAL Age range Adult Child or Adult
Skin Raynaud's
Mechanic's hands
Heliotrope rash
Interstitial lung disease Common Uncommon
Myalgias Common Occasional
ANTIBODY Myositis-specific Jo-1
tRNA synthetase
Mi-2
p140; p155
MUSCLE
  PATHOLOGY
Focal inflammation
  Location
  Type
 

Perimysium
Macrophage-like

 

Perivascular,
Mononuclear cells
Often with CD20 cells
Perimysium pathology
  Fragmentation
  Cellularity
  Without myopathy
  Alkaline phophatase staining

Common
Macrophage-like
Some patients
Some patients

Occasional
Mononuclear
Never
Unusual
Perifascicular muscle fibers
  COX staining reduced
  Necrosis & Regeneration
  Internal architecture

Never
Common
Regeneration

Most patients
Unusual
Vacuoles & Aggregates
Capillaries near
perifascicular pathology

  Ulex staining
  C5b9 deposition
  Alkaline phophatase staining


Normal
Absent 
Absent


Absent
Common 
Common




H&E stain

Perimysial fragmentation
  • The perimysium is loculated with many focal clear areas
  • Cells in the perimysium are most frequently macrophages. Features include
  • Adjacent muscle fibers may be normal (Bottom left) or show


H&E stain

Perimysial inflammation

Acid phosphatase

Perimysial cells: Acid phosphatase positive

Acid phosphatase

Perimysial cells: Acid phosphatase positive


Esterase

Perimysial inflammation
Esterase positive macrophages

Acid phosphatase stain

CD-68 positive cells in perimysium
  and endomysium



Alkaline phosphatase stain

Alkaline phosphatase staining of perimysium


H&E stain

Perifascicular myopathy & atrophy
Regeneration & Necrosis of perifascicular fibers

Immunocytochemistry

N-CAM positive atrophic muscle fibers
 

Return to Inflammatory myopathies
Return to Jo-1 myositis

11/18/2009