NEW YORK – Because juvenile dermatomyositis is a rare disease and its symptoms often differ from those seen in adult dermatomyositis, physicians may not recognize it and diagnosis can be delayed, Dr. Brian Feldman said.
He described a recent practice survey that found variability in juvenile dermatomyositis (JDM) treatment and, in the absence of randomized controlled trials, urged clinicians to consult newly created consensus protocols developed by rheumatologists and to gather data that may help to optimize treatment and minimize side effects in the future for those with JDM.
Photo courtesy http://en.wikipedia.org/wiki/File:Dermatomyositis4.jpg
Gottron's papules, as shown above, appear on JDM patients.
Dr. Feldman described a 15-year-old patient who had progressively deteriorated over a 3-year period despite being seen by pediatricians and dermatologists. His initial symptoms included fatigue and elevated muscle enzymes, including aspartate transaminase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK).
Within a year, the patient developed a purple skin rash on his hands, elbows, and knees. He later developed Raynaud's syndrome and muscle weakness with decreased range of motion that interfered with participation in sports and other activities of daily living.
Upon examination, he was quite thin with a scaly rash over his knuckles (Gottron's papules), healing skin ulcerations on his hands (from severe Raynaud's), periungual erythema, and lipodystrophy and erythema of his forearms. Magnetic resonance imaging showed acute inflammation of his shoulder girdle, said Dr. Feldman, chief of pediatric rheumatology at the Hospital for Sick Children in Toronto.
Dr. Feldman said that one of the best diagnostic clues for JDM comes from microscopic examination of nail folds. In this case, the patient had tortuous, bushy nail folds, dilated or missing capillaries (capillary density of 3 per mm of nailfold length while normal ranges from 7-11 per mm), and cuticular overgrowth indicative of JDM.
The different presentation seen with children compared with adults may hinder a correct diagnosis. For instance, calcinosis is seen much more frequently in children than adults. Children are less likely to have some of the systemic symptoms, such as fever, poor weight gain, and pulmonary effects, and they almost never have cardiac problems. Unlike adults with dermatomyositis or polymyositis who appear to have a fourfold increased risk of malignancy, very few cases of malignancy have been associated with JDM. Children are more likely to experience dysphonia/dysphagia but are as likely to have arthritic symptoms (around 58% of each group). Myositis specific antibodies do not seem to play as important a diagnostic role for children as adults.
Children who develop JDM appear to have a better prognosis than adults. Although adults with myositis have appreciable mortality (about 10%) and progressive disability, which may be related to treatment of a long-term condition such as avascular necrosis or osteoporosis with compression fracture, findings from Dr. Feldman's group show that outcomes were often excellent in children. "We have not had a single death from JDM in 30 years," he said.
About two-thirds of children with JDM have a polycyclic, chronic, unremitting disease course, but about one-third follow a monocyclic course and have disease symptoms that last for 2-3 years and then go away, with, or potentially even without, treatment.
In a very small proportion of these patients, symptoms may return many years later. "The message here is that when the disease goes away, it almost certainly is gone forever," Dr. Feldman noted.
It is possible to predict which patients will follow a chronic course and which patients will have early remission. In his experience, the risk of persistent disease falls by half if Gottron's rash disappears within 3 months of diagnosis (Arthritis Rheum. 2008;58:3585-92).
The results of a recent practice survey by the Childhood Arthritis and Rheumatology Research Alliance (CARRA) of almost 200 pediatric rheumatologists in North America found both similarities and differences in treatment approaches to JDM (J. Rheumatol. 2010;37:1953-61).
Corticosteroids and methotrexate (MTX) are mainstays of care, but the route and pattern of corticosteroid administration varied: 82% of respondents initially pulsed with high-dose intravenous methylprednisolone (IVMP) while 18% prescribed oral prednisone. MTX was used concurrently with steroids 84% of the time. Sixteen percent reported also using IV immunoglobulin, with or without MTX, for more severe disease, refractory disease, and prominent cutaneous disease. Hydroxychloroquine was given for milder cases, especially for rash, while cyclophosphamide was prescribed for ulcerative disease or for patients with pulmonary symptoms.
While these findings reflect the current prescribing practices, there are almost no randomized controlled trials of medications for JDM, Dr. Feldman pointed out.
This reflects in part the rare nature of the disease, its complexity, the difficulty of conducting studies in children, and the high cost of randomized controlled trials. There have been studies using advanced analytic techniques to provide strong comparative data in lieu of an randomized controlled trial. One such study by Dr. Feldman and associates (Arthritis Rheum. 2008;59:989-95) showed that more aggressive corticosteroid therapy does not give better 3-year outcomes.