DERMATOMYOSITIS

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 Dr. Lehman is the author of many textbook chapters and articles on the care of children and young adults with dermatomyositis and related conditions.  He practices in New York City.  Click here for more information about Dr. Lehman or the Hospital for Special Surgery.

If you want a more detailed discussion of childhood dermatomyositis
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What is dermatomyositis?

Dermatomyositis is an acute inflammatory condition of skin and muscle. There are several distinct types of dermatomyositis which may ultimately prove to be different diseases. Most often dermatomyositis presents with increasing fatigue and loss of proximal (thighs and shoulders) muscle strength accompanied by a heliotrope rash. The characteristic clinical history is simply of a child who is not able to 'keep up', or who is asking to be carried more and more often. Difficulty going up and down stairs is often the manifestation which prompts the family to seek medical attention. These findings may occur with other illnesses, but a careful pediatric rheumatologist can often make the diagnosis on the initial examination. This is because many children have vasculitic lesions of the nail beds ('nailfold capillary dilatation) and lesions of the skin overlying the proximal interphalangeal joints (Gottren's papules). These findings almost invariably signal dermatomyositis or a similar rheumatic disease (scleroderma or progressive systemic sclerosis). Less frequently the onset of dermatomyositis can be rapid with fever, widespread vasculitic rash and profound weakness. Both rapid and gradual onset of disease are often accompanied by a sense of being unwell (malaise) and may be complicated by fever and severe muscle wasting. Laboratory evaluation typically shows elevation of the CPK, SGOT, and aldolase, although in some cases only the CPK or aldolase may be abnormal.

Although not pathologically distinguishable, three distinct patterns of childhood dermatomyositis are clinically recognized. The most common group consists of children with proximal muscle weakness, mild heliotrope rash and no findings suggestive of vasculitis. These children often have a benign illness which resolves over a four to six month period with corticosteroid therapy. In contrast, children with a marked vasculitic rash, or typical findings of vascular involvement in the nail beds (nail-fold capillary abnormalities), or inflammatory papules overlying the interphalangeal joints (Gottren's papules) most often have a more chronic relapsing course. Their disease typically improves with corticosteriod or immunosuppressive therapy, but recurs. Less frequently seen are children with severe rash, markedly elevated muscle enzyme levels, but only moderate weakness. This special subgroup of children is often refractory to therapy and may be an entirely different disease.

Another unusual group of children who may be mistakenly diagnosed as dermatomyositis consists of children who are incidentally found to have markedly elevated CPK levels (e.g. 20,000 units) when being screened for another reason. These children are not weak, do not have a heliotropic rash, and remain well without therapy. Although the precise explanation for this group is unknown, they most likely have a simple biochemical defect. Muscular dystrophy also may present with very high CPK levels, but these children are weak.

What do I have to watch out for?

Vasculitic complications of dermatomyositis can occur in a variety of organs. Mental changes, skin rashes, abdominal pain, and chest infections are all well recognized complications of dermatomyositis which may be associated with severe problems. Arthritis may also complicate dermatomyositis but usually responds to the initiation of corticosteroid therapy.

How is it treated?

Prednisone in dosages of 0.5 to 2.0 mg/kg/day (depending on the severity of the presentation) are the treatment of choice for mild to moderate dermatomyositis. Special care must be taken to evaluate the swallowing function and gag reflex of children at the time of presentation or disease flare since aspiration is a prominent hazard for those with severe involvement. Chronic abdominal pain is a common nonspecific finding which may also necessitate a higher corticosteroid dosage. Although it may be benign, in some children it results from small vessel vasculitis of the bowel. This can be associated with multiple small areas of thrombosis and infarction which may perforate with catastrophic consequences. A less frequent indication for high dose prednisone is the presence of cerebritis which may be associated with hallucinations and dementia. Retinal vasculitis may also be present.

In most situations the corticosteroid dosage can be monitored by following serial CPK or aldolase levels. The treating physician must be aware that prednisone themselves may cause muscle weakness (steroid myopathy). If the patient is becoming weaker without a corresponding increase in the muscle enzyme levels, it may be necessary to rapidly taper the corticosteroid dosage. However, this may be associated with a disease flare. 'IV bolus' prednisone are useful if a rapid response is need for critically ill children with dermatomyositis, but are associated with potentially severe side effects.

For some children the heliotrope rash remains a significant problem despite clinical improvement in muscle strength with corticosteroid therapy. Hydroxychloroquine may be beneficial for these children in preference to raising the corticosteroid dosage. If corticosteroid containing topical preparations are recommended, careful consideration must be given to potential long-term side-effects including subcutaneous atrophy.

Most children will recover completely with prednisone alone. However, some will have persistent, active disease or develop unacceptable corticosteroid side effects. Methotrexate is often beneficial for these children. Low dose oral methotrexate at 10 mg/M2, which has been very useful for JRA, has been relatively ineffective for childhood dermatomyositis. Larger doses of methotrexate (0.1 mg/kg gradually increased to 1 mg/kg) administered weekly, intramuscularly or intravenously, have been associated with a dramatic improvement. Hepatic toxicity and white blood cell levels must be monitored carefully. Intravenous methotrexate therapy in this dose range may also be associated with significant nausea, which may be reduced by premedication. For most children the maximum necessary dosage of methotrexate is 1 mg/kg (with a maximum of 50 mg). However, higher doses have been used successfully in selected cases.

Intravenous cyclophosphamide therapy has also been used successful in many centers for children with severe dermatomyositis. A variety of regimens have been utilized ranging from 10 mg/kg weekly to 1 gm/M2 monthly. As with methotrexate, cyclophosphamide administration requires careful monitoring of hematological parameters. Cyclophosphamide has the advantage of not being associated with hepatic cirrhosis, but methotrexate is less strongly associated with a subsequent risk of sterility or neoplastic disease. In addition, methotrexate can be administered on an outpatient basis without concern about possible bladder toxicity.

New studies suggest the etanercept or other agents which block tumor necrosis factor (TNFa) may be less toxic and more effective in treating children with dermatomyositis.  Dr. Lehman is now using this therapy at the Hospital for Special Surgery.  “We have had some children dramatically improve, but others do not” says Dr. Lehman.  The right answer and how children with dermatomyositis may differ in their response to drugs isn’t yet clear.

Limited experience is available with the use of intravenous gammaglobulin therapy. In small studies it has been associated with a significant steroid sparing effect. However, prolonged therapy was required (nine months) and flares occurred when treatment was discontinued. The excessive costs of this therapy make these limited benefits of questionable utility unless the patient has failed to respond to less costly therapies. There is also an increasing experience with cyclosporine A. Despite initially promising results many centers report a general lack of long term efficacy. No controlled studies have been reported.

Diffuse calcification of subcutaneous tissues or muscle groups is a potential complication of dermatomyositis which may be severely debilitating. Small areas of discrete calcification do not warrant surgical intervention unless they are causing discomfort. Larger areas should be treated conservatively if at all possible. Poor wound healing often results in an unsatisfactory surgical result. Recurrent episodes of inflammation at sites of calcification may be continuing sources of discomfort for the patient. Colchicine (0.6 mg b.i.d.) may be helpful in reducing the frequency of these episodes.   Some experts have had excellent success using bisphosphonates to reduce the calcifications.  Secondary infection of calcium deposits which have broken through the skin is a constant concern, and cellulitis may require intravenous antibiotic therapy.

A few patients will develop severe, diffuse calcification (calcinosis universalis) following the acute phase of their dermatomyositis. This complication is associated with severe restriction. No satisfactory regimen for alleviating this condition has been found. Regimens such as editronate which interfere with calcification have more profound effects on normal than ectopic bone resulting in an unacceptable frequency of fractures. Although low dose warfarin therapy has been recommended, most centers have found it ineffective and potentially dangerous. The extreme weakness and poor mobility of these patients are often complicated by depression and malaise with resultant inanition. Pneumonia secondary to poor chest wall function and resultant cardiorespiratory function is a frequent cause of death. These patients require a multidisciplinary team approach and are best referred to centers with extensive experience in their management.

In addition to medical management, patients with dermatomyositis or polymyositis require an ongoing program of physical and occupational therapy to prevent continuing weakness and the development of contractures. Passive range of motion and icing are of benefit even during periods of active muscle inflammation, but active range-of-motion and isometrics should be withheld until the muscle enzyme levels are declining.

What is the long term outlook?

The long term outlook for children with dermatomyositis is good. Although some children do have very severe disease most will eventually recover nearly full function.

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Reviewers comments on Its Not Just Growing Pains

    Dr. Tom Lehmans experience and compassion are evident on every page of this book, and they help guide the readerchild, parent, and healthcare professional alike through the world of childhood arthritis.  This book is an absolute gem written with a single goal in mind:  improve the lives of kids with arthritis. -- Jack Klippel, M.D. President and CEO of the Arthritis Foundation

 

     Dr. Lehman has given parents and families of children with arthritis the first book that speaks to the parent and child as equals.  His book explains the illnesses, the medications, the lab tests, and the disease course in simple, understandable lay language and givens them valuable insight into how a pediatric rheumatologist thinks.  Bravo!-- Charles Spencer, M.D., Professor of Clinical Pediatrics, University of Chicago, La Rabida

It’s not just growing pains.
A guide to childhood muscle, bone, and joint pain,
rheumatic diseases and the latest treatments

 

Click here to see the table of contents

 

It has always been a frustration trying to answer the many questions I have received from people over the web.  I can’t take the time and give them the detail I would like to.  I have to take care of my patients.  This book is a distillation of my experience answering questions for parents and health professionals over 25 years of practice.  If you want to know about the diseases, the tests, the medications, or how to be sure you are getting the best care– If you are the family member of a child with joint pains, this book will give you the answers.  There is an entire chapter just on dermatomyositis.  If you are a general physician, a pediatrician, or a nurse who cares for children with these diseases it will answer many of the questions families ask you, and you can recommend it to them.  It will also answer many of your questions about what shots to give, what precautions to take, and the other questions families, pediatricians, and other health care providers have asked me over the years.

 

Dr. Lehman is the author of many textbook chapters and articles on the care of children and young adults with rheumatic diseases including SLE, JRA, dermatomyositis, scleroderma, Kawasaki disease and related conditions.  He practices in New York City.  Click here for more information about Dr. Lehman or the Hospital for Special Surgery.

Click here if you are interested in making an appointment to see Dr. Lehman

 

Resources:

If you are interested in books about childhood rheumatic disease click here

In the United Kingdom there is a support group for adults and children with dermatomyositis or polymyositis which can be reached at D and P support group, 146 Newton Rd, Woolston, Southampton SO19 9HR.

Dr. Lehman is the author of many textbook chapters and articles on the care of children and young adults with SLE.  He practices in New York City.  Click here for more information about Dr. Lehman or the Hospital for Special Surgery.

The Arthritis Foundation also works with children with dermatomyositis.

Click for BOOKS dealing with childhood rheumatic diseases

This site provided by Thomas J. A. Lehman MD
Chief, Division of Pediatric Rheumatology
The Hospital for Special Surgery
535 E 70 St,
New York, NY 10021
212-606-1151, fax 212-606-1938, e-mail goldscout@aol.com

 

 

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