Dermatomyositis 4.75/5 (4)

Last updated: 28 / 12 / 20
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dermatomyositis

"Dermatomyositis" by Elizabeth M. Dugan, Adam M. Huber, Frederick W. Miller, Lisa G. Rider - http://dermatology.cdlib.org/1502/reviews/photoessay/1.jpg. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Dermatomyositis.jpg#/media/File:Dermatomyositis.jpg

Dermatomyocyte (ICD10 M33.1)

Definition

Dermato-myositis is part of Myositis (muscle inflammation) diseases. There are several types. The symptoms overlap, and are in Dermatomyositis characterized by rheumatic inflammation of the muscles (high creatine kinase / CK in the blood and muscle weakness) and a rash. Often, the pattern in the tissue sample (biopsy) from the muscle and sometimes the rash in the blood samples (Antibodies) differentiate dermato-myositis from other types of myositis.

Division of myocyte is described in more detail on this page Myositis.

Dermatomyositis

Dermato-myocyte on hands, knee, neck and neck. Marvi U, 2012. CC BY NC SA 3.0

Disease Causes

The cause of dermatomyositis is unknown in most cases

  • Dermatomyositis in adults is associated with posterior cancer in some cases
  • Once the disease has started, we know that the body's own immune system accidentally attacks the muscles and skin (Autoimmune disease). Internal organs, especially lungs and the heart, can also be damaged
  • In severe muscle inflammation, the kidneys may also fail

Occurrence

Myositis diseases are rare with 1-8 cases per 100.000 population (prevalence). Dermatomyocyte and Polymyocyte occur about as frequently (reference: Dobloug C, 2015). The number of new people receiving the disease per year is estimated at 0,5-8 per million, which corresponds to approx. 25 new cases in Norway annually (incidence). Dermatomyocyte is thus defined as one rare disease.

  • Women are attacked twice as frequently as men
  • Most people get sick at the age of 50, but also children (most often Juvenile dermatomyositis) and older people can be attacked

Symptoms

The skin

The skin is attacked by Dermatomyositis

  • It can have red-purple color changes over the fingers knuckles, stretch side (extensor) of elbows and knees (GOTTRONs characters / papers)
  • Colored people get pigmented, dark, skin changes
  • Some also get skin changes on the neck and neck areas (V- sign or shawl- sign).
  • Cracked and torn skin on fingers is often referred to as "mechanic hands".
  • Red-purple or dark areas on and around the upper eyelid are called Heliotropic rash.
  • Calcium deposition (calcium) under the skin occurs especially among children with (juvenile) dermatomyositis

Dermatomyositis with red face and swollen eyelids. Illustration: By Elizabeth M https://commons.wikimedia.org.  CC BY SA 3.0

Dermatomyositis

Illustration: V signs are redness of the throat and chest at Dermatomyositis. Openi. Affiliation: Department of General Surgery, Changi General Hospital, Singapore. CC BY 4.0

Muscles

Myocyte symptoms with gradual deterioration develop gradually over weeks and months. Less than half feel that the muscles are painful

  • Gradually weakened muscle strength in the thighs may prove to be progressively difficult to rise from squatting or from the chair
  • Weak upper arms cause problems in lifting the arms over the head. In some, the neck muscles become weak so that the head feels heavy to hold
  • In myositis, blood samples show elevated muscle enzymes (CK, LD and ASAT) in active disease.
  • Muscle pain may also have other causes, please read more here.

Lungs

However, dermatomyositis can occur without any particular inflammation of the muscle, but with significant skin and / or lung disease.

  • Some first experience lung symptoms with strikingly heavy breathing through physical exertion

Diagnosis

  • Typical skin symptoms
  • Reduced muscle strength
  • Blood tests show
  • EMG (Electromyography)
    • May differentiate myocyte from neurogenic muscle disease
  • MRI of muscles (most often thigh muscles)
    • Symmetrical edema

Tissue sample

muscle

  • Dermatomyositis with typical inflammatory infiltrate around blood vessels in muscles peri-fascicular rheumatic (autoimmune") and not in the endomysia / muscle cell itself, unlike Polymyocyte which has endo-myseal inflammation

Skin

  • Tissue testing may show inflammation (inflammation) suspected of systemic connective tissue disease, but is not critical / specific to diagnosis

Cancer and Dermatomyositis

Dermatomyositis in adults may initially be associated with cancer. It is therefore common to examine for this (CT thorax and abdomen, mammography, stool specimens, possibly PET / CT with more)

Criteria for diagnosis

Incorrect diagnosis (similar conditions, differential diagnoses)

Pregnancy

Myocyte onset during pregnancy carries the risk of fetal damage. Some women with myositis have SSA antibody (as by Seagrass syndrome / pregnancy) which can cause heart problems (heart block) in the fetus. Low rashes in SSA are most common in myositis and carry a lower risk than high rashes. In a calm disease phase, myositis pregnancy has a good prognosis. Nevertheless, myositis pregnancy is generally perceived as a "risk pregnancy". One should be followed up by the maternity ward and rheumatologist. Prior to pregnancy, it is important that any medication use is reviewed by a specialist.

In particular, one must examine whether the medication can continue in a pregnancy or must be changed. 

Read more about pregnancy in rheumatic diseases here

Treatment

Before starting treatment, it is important that one is aware of the disease and the treatment objective and the side effects that may occur. Treatment goal is to stop the disease completely, ie obtain remission. Unfortunately, there is no treatment that heals the disease.

  • Dermatomyositis is treated quite like other types of Myositis (please see treatment on the side about Myositis). Treatment must be adapted to the individual's illness and situation. The principle is to reduce the rheumatic inflammation of the muscle and possibly skin with immunosuppressive drugs
  • Custom physical exercise is also useful, but must be instructed (physiotherapist) so that it does not overload
  • It is not shown that a special diet or alternative medicines have effect
  • In dermatomyositis one should be especially careful about tanning (use high factor sunscreen)
  • In severe eczema, skin is treated by dermatologist

Medical prognosis and outlook for dermato-myositis

The course of the disease is clearly different from person to person and depends on the type of myocyte present. For Polymyocyte and Dermatomyocyte generally apply:

  • Most people respond well to treatment and regain muscle strength within a few weeks. In others, it may take longer
  • Most people need medication for several years to prevent the recurrence of the disease. In the longer term (years), the disease can settle down. The treatment is then stepped down and stopped
  • The severity of the disease is often determined by internal organs, especially lungs (see Antisynthetase syndrome), is attacked and whether treatment is well tolerated
  • During treatment, about 1 / 3 is better, 1 / 3 is not exacerbated while 1 / 3 is getting worse over time (Reference: Fathi M, 2008).
  • In dermatomyositis in adults, the disease may be associated with concomitant cancer. In that case, this may also determine the forecast

Guidelines

Lundberg IE, 2017: EULAR Classification of myositis 

Rheumatological Association / Legeforeningen 2020

Literature

Tips for investigating myositis here

Keywords for myositis journal writing here

Keywords for referring myocyte to specialist here

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