|A Perspective on Juvenile Systemic Sclerosis|
|Sunday, 13 March 2011 15:22|
Juvenile systemic sclerosis is one of the most serious rheumatologic diseases diagnosed in children and adolescents, according to Dr. Ivan Foeldvari. This complex disorder is characterized by fibrosis of the skin, subcutaneous tissues, and internal organs, as well as vascular and immune system abnormalities. The pediatric version of the condition shares many features with the adult connective tissue disease, but there are marked differences in its presentation and management in children, so lessons learned from adult cases cannot always be extrapolated to pediatric patients, he said.
Dr. Foeldvari discusses some of the distinctions between the adult and pediatric conditions, as well as the most important diagnostic and management considerations in the treatment of children with the disease.
Question: What are some of the clinical manifestations of systemic sclerosis in children and how do they differ from the disease in adults?
Dr. Foeldvari: Currently, we have only retrospective data regarding the presentation of juvenile systemic sclerosis, because pediatric cases are relatively rare [comprising approximately 3% of all systemic sclerosis diagnoses]. Based on information from the two largest case collections – one containing 153 patients (Arthritis Rheum. 2006;54: 3971-8) and the other containing 135 patients (Rheumatology 2000;39: 556-9) – the female:male ratio of children with the disease ranges from 2.8:1 to 3.6:1, which differs significantly from the adult-onset disease in which the female dominance is clearly more pronounced. With respect to the disease subset distribution, approximately 90% of the juvenile-onset cases have a diffuse subset according to the LeRoy classification (J. Rheumatol. 1988;15:202-5), whereas the limited form of the disease is rare in children. In fact, in the 153 case study, only 1 patient was reported to have CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) syndrome, which fits with the low prevalence of the limited subset in this population. In contrast, approximately 40% of patients in adult cohorts have a diffuse subset, whereas the CREST syndrome is quite common.
RN: What are the classification criteria for the pediatric form of the disease?
Dr. Foeldvari: Until 2007, there were no specific classification criteria for juvenile systemic sclerosis. Patients with the condition were classified according to the preliminary ACR (American College of Rheumatology) criteria and later on according to the LeRoy criteria. None of these criteria was ever prospectively validated in children. In 2007, a new provisional classification system for juvenile systemic sclerosis was the first one proposed just for pediatric-onset patients (Arthritis Rheum. 2007;57:203-12). It is endorsed by the Pediatric Rheumatology European Society (PReS), the ACR, and the European League Against Rheumatism (EULAR). It differs from the adult classification criteria, which was established in 1980 and includes the presence of one major criterion (namely, symmetrical thickening of the skin proximal to the metacarpophalangeal or metatarsophalangeal joints) or two or more minor criteria (including sclerodactyly, digital pitting scars or loss of substance from the finger pad, and bibasilar pulmonary fibrosis). According to the newly proposed pediatric criteria, the patient has to fulfill one major and two minor criteria, with an age of onset of the disease at younger than 16 years. The major criterion is proximal skin sclerosis/induration of the skin. The minor criteria are defined by scleroderma-specific organ involvement and/or by specific serologic findings, which are listed and defined in the classification paper. The criteria need to be validated prospectively, which is the objective of the prospective Inception Cohort for Juvenile Systemic Sclerosis project (www.juvenile-scleroderma.com).
The anticipated advantage of the juvenile criteria is that the classification of the patient can be made based not only on pulmonary involvement, but also on other scleroderma-specific organ involvement or antibody profile, allowing patients to be diagnosed earlier in the disease course.
RN: What are the most important diagnostic considerations?
Dr. Foeldvari: Raynaud phenomenon is the presenting symptom in 75% of the pediatric patients at the time of diagnosis. Sclerodactylia is another key feature at onset, but it is present only in approximately 37% of patients. Capillaroscopic changes are also often present, but capillaroscopy has not been prospectively evaluated in juvenile systemic sclerosis patients. One problem with capillaroscopy for diagnosis is that studies have shown that capillary changes in the pediatric age group behave differently from those in adults. Similar discrepancies have been reported for skin changes. For example, studies have shown that the modified Rodnan skin score, which is validated in adults, cannot automatically be applied to pediatric patients because healthy children have a significantly increased skin score using this measure. The modified Rodnan skin score in children correlates with body mass index and Tanner stage, so it has to be corrected to these parameters.
With respect to laboratory values, there is no specific antibody that has to be present to prove the diagnosis in children, but because most children have a diffuse subset, anti-Scl70 [which appears to discriminate between progressive systemic sclerosis and limited subsets] is more frequent than in adults, occurring in approximately 34% of cases. Anticentromere antibodies are observed in 0%-7% of pediatric patients, and sedimentation rate and C-reactive protein inflammatory markers are estimated to be elevated in up to 38% and 13% of patients, respectively.
RN: Have specific biological markers been identified?
Dr. Foeldvari: Biological markers of disease or organ involvement are of increasing interest because they enable us to diagnose and follow certain organ involvement or disease activity noninvasively. Currently, the possibility of anti-KL6 as a serum marker for interstitial lung involvement in children with juvenile systemic sclerosis is being investigated, as is the prognostic value of B-type natriuretic peptide in children with pulmonary hypertension. For the evaluation of cardiac, renal, or central nervous system involvement, the same methods that are used in adults are employed.
Source: Mahoney, D. (2011), "Perspective – Juvenile Systemic Sclerosis", Elsevier Global Medical News; original article can be viewed here.