Juvenile dermatomyositis
Encyclopedia
Juvenile dermatomyositis (JDMS) is an autoimmune disease
causing vasculitis
that manifests itself in children; it is the pediatric counterpart of dermatomyositis
. In JDMS, the body's immune system
attacks blood vessels throughout the body, causing inflammation
called vasculitis
. In the United States
, the incidence rate of JDMS is approximately 3 cases per million children per year, leading to 300 to 500 new cases annually and affecting an estimated 3,000 to 5,000 children. Other forms of juvenile myositis are juvenile polymyositis
(JPM) and juvenile inclusion-body myositis (JIBM), which are extremely rare and are not as common in children as in adults.
component, as other auto-immune disease tend to run in the families of patients. The disease is usually triggered by a condition that causes immune system activity that does not stop as it should, but the trigger is almost certainly not the cause in most cases. Common triggers include immunization
s, infection
s, injuries, and sunburn
.
One is a distinctive rash
. The rash often affects the face
, eyelid
s, and hand
s, and sometimes the skin above joints, including the knuckle
s, knee
s, elbow
s, etc. The color of the rash is a pinkish purple, and is called heliotrope
(after a flower of the same name with approximately this color). On the hands and face, the rash very closely resembles allergies
, eczema
, fifth disease
, or other more common skin condition, but the heliotrope color is unique to the inflammatory process of JDMS. Some children develop calcinosis
, which are calcium deposits under the skin. The rash is the source of the "dermato-" part of the name of the disease.
The second symptom caused by vasculitis is muscle inflammation. This symptom is the source of the "-myositis" part of the name of the disease ("myo" = muscle, "-itis" = inflammation of). Muscle Inflammation causes muscle weakness
, which can cause fatigue
, clumsiness, not keeping up physically with peers, and eventually inability to perform tasks like climbing stairs, lifting objects, and performing other manual tasks. Other signs may include falling, dysphonia
, or dysphagia
. The muscle weakness often causes a medical misdiagnosis of muscular dystrophy
or other muscle disease. Some patients develop contractures, when the muscle shortens and causes joints to stay bent; exercise can prevent this. The muscles first affected tend to be proximal (i.e., neck, shoulders, back, and abdominal). About half of children with JDMS also have pain in their muscles.
, Solu-Medrol), followed by a high dose of oral prednisone
(usually 1–2 mg/kg of body weight) for several weeks. This action usually brings the disease under control, lowering most lab tests to or near normal values. Some minor improvement in muscle symptoms may also be seen in this time, but normally it takes a long time for full muscle strength to be regained.
Once the disease process is under control, oral steroids are tapered gradually to minimize their side effects. Sudden withdrawal of oral steroids is dangerous. Often, steroid-sparing drugs, such as methotrexate
(a chemotherapy
drug) or other DMARDs, are given to compensate for the reduction in oral steroids. Once the oral steroids are reduced to a less toxic level, the sparing agents can also be gradually withdrawn. Lab results are closely monitored during the tapering process to ensure that the disease does not recur.
In the cases where steroids or second-line drugs are not tolerated or are ineffective, there are other treatments that can be tried. These include other chemotherapy drugs, such as ciclosporin
, infliximab
, or other DMARDs. Another is intravenous immunoglobulin
(IVIg), a blood product that has been shown to be very effective against JDMS.
To treat the skin rash, anti-malarial drugs, such as hydroxychloroquine
(Plaquenil) are usually given. Topical steroid creams (hydrocortisone) may help some patients, and anti-inflammatory creams (such as tacrolimus
) are proving to be very effective. Dry skin caused by the rash can be combated by regular application of sunscreen
or any moisturizing cream, such as Eucerin. Most JDM patients are very sensitive to sun exposure, and sunburn may be a disease activity trigger in some, so daily application of high-SPF sunscreen is often recommended.
Autoimmune disease
Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...
causing vasculitis
Vasculitis
Vasculitis refers to a heterogeneous group of disorders that are characterized by inflammatory destruction of blood vessels. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis...
that manifests itself in children; it is the pediatric counterpart of dermatomyositis
Dermatomyositis
Dermatomyositis is a connective-tissue disease related to polymyositis and Bramaticosis that is characterized by inflammation of the muscles and the skin.- Causes :...
. In JDMS, the body's immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
attacks blood vessels throughout the body, causing inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
called vasculitis
Vasculitis
Vasculitis refers to a heterogeneous group of disorders that are characterized by inflammatory destruction of blood vessels. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis...
. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the incidence rate of JDMS is approximately 3 cases per million children per year, leading to 300 to 500 new cases annually and affecting an estimated 3,000 to 5,000 children. Other forms of juvenile myositis are juvenile polymyositis
Polymyositis
Polymyositis is a type of chronic inflammation of the muscles related to dermatomyositis and inclusion body myositis.-Signs and symptoms:...
(JPM) and juvenile inclusion-body myositis (JIBM), which are extremely rare and are not as common in children as in adults.
Cause
The underlying cause of JDMS is unknown. It most likely has a geneticGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
component, as other auto-immune disease tend to run in the families of patients. The disease is usually triggered by a condition that causes immune system activity that does not stop as it should, but the trigger is almost certainly not the cause in most cases. Common triggers include immunization
Immunization
Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent ....
s, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
s, injuries, and sunburn
Sunburn
A sunburn is a burn to living tissue, such as skin, which is produced by overexposure to ultraviolet radiation, commonly from the sun's rays. Usual mild symptoms in humans and other animals include red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV...
.
Symptoms
The vasculitis caused by JDMS manifests itself predominantly in two ways:One is a distinctive rash
Rash
A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...
. The rash often affects the face
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
, eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
s, and hand
Hand
A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...
s, and sometimes the skin above joints, including the knuckle
Knuckle
The knuckles are the joints of the fingers and toes, which are brought into prominence when the hand is clenched and a fist is made. The word is cognate to similar words in other Germanic languages, such as the Dutch "Knokkel" or German "Knöchel" , i.e., Knöchlein, the diminutive of the German...
s, knee
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
s, elbow
Elbow
The human elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm....
s, etc. The color of the rash is a pinkish purple, and is called heliotrope
Heliotropium
Heliotropium is a genus of flowering plants in the borage family, Boraginaceae. There are 250 to 300 species in this genus, which are commonly known as heliotropes ....
(after a flower of the same name with approximately this color). On the hands and face, the rash very closely resembles allergies
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
, eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...
, fifth disease
Fifth disease
Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called 'apple sickness' or...
, or other more common skin condition, but the heliotrope color is unique to the inflammatory process of JDMS. Some children develop calcinosis
Calcinosis
-Dystrophic calcification:The most common type of calcinosis is dystrophic calcification. This type of calcification can occur as a response to any soft tissue damage, including that involved in implantation of medical devices.-Metastatic calcification:...
, which are calcium deposits under the skin. The rash is the source of the "dermato-" part of the name of the disease.
The second symptom caused by vasculitis is muscle inflammation. This symptom is the source of the "-myositis" part of the name of the disease ("myo" = muscle, "-itis" = inflammation of). Muscle Inflammation causes muscle weakness
Muscle weakness
Muscle weakness or myasthenia is a lack of muscle strength. The causes are many and can be divided into conditions that have true or perceived muscle weakness...
, which can cause fatigue
Fatigue (physical)
Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
, clumsiness, not keeping up physically with peers, and eventually inability to perform tasks like climbing stairs, lifting objects, and performing other manual tasks. Other signs may include falling, dysphonia
Dysphonia
Dysphonia is the medical term for disorders of the voice: an impairment in the ability to produce voice sounds using the vocal organs . Thus, dysphonia is a phonation disorder...
, or dysphagia
Dysphagia
Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia....
. The muscle weakness often causes a medical misdiagnosis of muscular dystrophy
Muscular dystrophy
Muscular dystrophy is a group of muscle diseases that weaken the musculoskeletal system and hamper locomotion. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue.In the 1860s, descriptions of boys who...
or other muscle disease. Some patients develop contractures, when the muscle shortens and causes joints to stay bent; exercise can prevent this. The muscles first affected tend to be proximal (i.e., neck, shoulders, back, and abdominal). About half of children with JDMS also have pain in their muscles.
Progression
The speed of the progression of JDMS is highly variable. Nearly all JDM patients have some skin involvement. The JDMS rash usually occurs as the initial symptom. Sometimes it is so slight as not to be recognized for what it is until muscle symptoms appear. Sometimes muscle symptoms never appear at all or occur very gradually over the course of months, and sometimes going from normal strength to being unable to walk within days. Usually, muscle symptoms appear weeks to months after the onset of the rash.Diagnosis
JDM is diagnosed by a combination of patient/parent observations, clinical examination, and laboratory blood tests. Very often muscle biopsies, and/or electromyography tests provide conclusive diagnosis.Treatment
Once a diagnosis of JDMS is made, the treatment is often a 3-day course of Intravenous ("pulse") steroids (methylprednisoloneMethylprednisolone
Methylprednisolone is a synthetic glucocorticoid or corticosteroid drug. It is marketed in the USA and Canada under the brand names Medrol and Solu-Medrol. It is also available as a generic drug....
, Solu-Medrol), followed by a high dose of oral prednisone
Prednisone
Prednisone is a synthetic corticosteroid drug that is particularly effective as an immunosuppressant drug. It is used to treat certain inflammatory diseases and some types of cancer, but has significant adverse effects...
(usually 1–2 mg/kg of body weight) for several weeks. This action usually brings the disease under control, lowering most lab tests to or near normal values. Some minor improvement in muscle symptoms may also be seen in this time, but normally it takes a long time for full muscle strength to be regained.
Once the disease process is under control, oral steroids are tapered gradually to minimize their side effects. Sudden withdrawal of oral steroids is dangerous. Often, steroid-sparing drugs, such as methotrexate
Methotrexate
Methotrexate , abbreviated MTX and formerly known as amethopterin, is an antimetabolite and antifolate drug. It is used in treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions. It acts by inhibiting the metabolism of folic acid. Methotrexate...
(a chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
drug) or other DMARDs, are given to compensate for the reduction in oral steroids. Once the oral steroids are reduced to a less toxic level, the sparing agents can also be gradually withdrawn. Lab results are closely monitored during the tapering process to ensure that the disease does not recur.
In the cases where steroids or second-line drugs are not tolerated or are ineffective, there are other treatments that can be tried. These include other chemotherapy drugs, such as ciclosporin
Ciclosporin
Ciclosporin , cyclosporine , cyclosporin , or cyclosporin A is an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the immune system, and therefore the risk of organ rejection...
, infliximab
Infliximab
Infliximab is a monoclonal antibody against tumour necrosis factor alpha . It is used to treat autoimmune diseases. Remicade is marketed by Janssen Biotech, Inc...
, or other DMARDs. Another is intravenous immunoglobulin
Intravenous immunoglobulin
Intravenous immunoglobulin is a blood product administered intravenously. It contains the pooled IgG extracted from the plasma of over one thousand blood donors. IVIG's effects last between 2 weeks and 3 months...
(IVIg), a blood product that has been shown to be very effective against JDMS.
To treat the skin rash, anti-malarial drugs, such as hydroxychloroquine
Hydroxychloroquine
Hydroxychloroquine is an antimalarial drug, sold under the trade names Plaquenil,Axemal, Dolquine, and Quensyl, also used to reduce inflammation in the treatment of rheumatoid arthritis and lupus...
(Plaquenil) are usually given. Topical steroid creams (hydrocortisone) may help some patients, and anti-inflammatory creams (such as tacrolimus
Tacrolimus
Tacrolimus is an immunosuppressive drug that is mainly used after allogeneic organ transplant to reduce the activity of the patient's immune system and so lower the risk of organ rejection...
) are proving to be very effective. Dry skin caused by the rash can be combated by regular application of sunscreen
Sunscreen
Sunblock is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn...
or any moisturizing cream, such as Eucerin. Most JDM patients are very sensitive to sun exposure, and sunburn may be a disease activity trigger in some, so daily application of high-SPF sunscreen is often recommended.