Dermatomyositis pathophysiology: Difference between revisions

Jump to navigation Jump to search
No edit summary
No edit summary
Line 4: Line 4:


==Overview==
==Overview==
==Pathophysiology==
==Pathophysiology==
The diagnosis of dermatomyositis can be confirmed by muscle biopsy, [[EMG]], and blood tests. It should be noted, however, that only muscle biopsy is truly diagnostic (pathognomic); liver enzymes and EMG are relatively non-specific. Liver enzymes, specificly creatine phosphokinase (CPK), are the major tool in assessing the progress of the disease and/or the efficacy of treatment. On the muscle biopsy, there are two classic microscopic findings of dermatomyositis.  They are:
On the muscle biopsy, there are two classic microscopic findings of dermatomyositis.  They are:
 
* A mixed [[B-cell|B-]] and [[T-cell]] perivascular inflammatory infiltrate
* A mixed [[B-cell|B-]] and [[T-cell]] perivascular inflammatory infiltrate
* Perifascicular muscle fiber atrophy
* Perifascicular muscle fiber atrophy
Line 16: Line 16:


===Microscopic findings===
===Microscopic findings===
 
Cross sections of muscle reveal muscle fascicles with small, shrunken polygonal muscle fibers on the periphery of a fascicle surrounding central muscle fibers of normal, uniform size.  
Cross sections of muscle reveal muscle fascicles with small, shrunken polygonal muscle fibers on the periphery of a fascicle surrounding central muscle fibers of normal, uniform size.
 
Aggregates of mature [[lymphocytes]] with small, dark nuclei and scant cytoplasm are seen surrounding vessels.  Other inflammatory cells are distinctly uncommon. [[Immunohistochemistry]] can be used to demonstrate that both B- and T-cells are present in approximately equal numbers.<ref>Benveniste O, Squier W, Boyer O, Hilton-Jones D, Herson S. ''Presse Med''. '''2004''' Nov 20;33(20):1444-50. PMID: 15611679</ref> <ref>Nirmalananthan N, Holton JL, Hanna MG. Is it really myositis? A consideration of the differential diagnosis. ''Curr Opin Rheumatol''. '''2004''' Nov;16(6):684-91.</ref>
Aggregates of mature [[lymphocytes]] with small, dark nuclei and scant cytoplasm are seen surrounding vessels.  Other inflammatory cells are distinctly uncommon. [[Immunohistochemistry]] can be used to demonstrate that both B- and T-cells are present in approximately equal numbers.<ref>Benveniste O, Squier W, Boyer O, Hilton-Jones D, Herson S. ''Presse Med''. '''2004''' Nov 20;33(20):1444-50. PMID: 15611679</ref> <ref>Nirmalananthan N, Holton JL, Hanna MG. Is it really myositis? A consideration of the differential diagnosis. ''Curr Opin Rheumatol''. '''2004''' Nov;16(6):684-91.</ref>



Revision as of 17:04, 30 October 2012

Dermatomyositis Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Dermatomyositis from other Diseases

Epidemiology and Demographics

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

X Ray

MRI

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Dermatomyositis pathophysiology On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Dermatomyositis pathophysiology

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Dermatomyositis pathophysiology

CDC on Dermatomyositis pathophysiology

Dermatomyositis pathophysiology in the news

Blogs on Dermatomyositis pathophysiology

Directions to Hospitals Treating Dermatomyositis

Risk calculators and risk factors for Dermatomyositis pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Pathophysiology

On the muscle biopsy, there are two classic microscopic findings of dermatomyositis. They are:

  • A mixed B- and T-cell perivascular inflammatory infiltrate
  • Perifascicular muscle fiber atrophy

Dermatomyositis is associated with autoantibodies, especially anti-Jo1 antibody.[1]

Mechanism

The mechanism is conjectured to be complement-mediated damage of microscopic vessels with muscle atrophy and lymphocytic inflammation secondary to tissue ischemia.[2]

Microscopic findings

Cross sections of muscle reveal muscle fascicles with small, shrunken polygonal muscle fibers on the periphery of a fascicle surrounding central muscle fibers of normal, uniform size. Aggregates of mature lymphocytes with small, dark nuclei and scant cytoplasm are seen surrounding vessels. Other inflammatory cells are distinctly uncommon. Immunohistochemistry can be used to demonstrate that both B- and T-cells are present in approximately equal numbers.[3] [4]

References

  1. Ghirardello, A (2006). "Clinical implications of autoantibody screening in patients with autoimmune myositis". Autoimmunity. 39 (3): 217–221. doi:10.1080/08916930600622645. PMID 16769655. Unknown parameter |coauthors= ignored (help); Unknown parameter |month= ignored (help)
  2. Benveniste, O (2004). "Pathogenesis of primary inflammatory myopathies". Presse Médicale. 33 (20): 1444–1450. doi:10.1016/S0755-4982(04)98952-X. PMID 15611679. Unknown parameter |coauthors= ignored (help); Unknown parameter |month= ignored (help)
  3. Benveniste O, Squier W, Boyer O, Hilton-Jones D, Herson S. Presse Med. 2004 Nov 20;33(20):1444-50. PMID: 15611679
  4. Nirmalananthan N, Holton JL, Hanna MG. Is it really myositis? A consideration of the differential diagnosis. Curr Opin Rheumatol. 2004 Nov;16(6):684-91.

Template:WH Template:WS