Juvenile dermatomyositis and polymyositis: a follow-up study of long-term sequelae

Abstract

Background: Juvenile dermatomyositis/polymyositis (DMS/PM) are childhood inflammatory myopathies that normally affect children between 2 and 15 years of age. The disease is manifested as severe proximal muscle weakness and, in JDMS, as a characteristic cutaneous eruption. It is difficult to predict the course of the disease. This study is aimed at objectively assessing the long-term morbidity of dermatomyositis/polymyositis in children.

Methods: Twelve cases of JDMS/PM identified through chart review were evaluated by physical and dermatologic examination, muscle testing, ultrasonography, and magnetic resonance imaging (MRI).

Results: The patient population included 6 male and 6 female patients with a mean age of 18.8 years (standard deviation 12.4). The mean age at onset of JDMS/PM was 5.8 years (SD 2.8), and the mean time from onset of symptoms to beginning of the study was 10.1 years (SD 9.3). The mean duration of corticosteroid therapy was 53.1 months (SD 40.5), with patients reporting an average of 1.7 relapses (SD 1.5). Patients compared their own activity level with that of healthy control subjects, and on a scale of 1 to 5 with 5 being normal, their mean score was 3.9 (SD 0.9). Fifty-eight percent of the patients had at least one residual finding on physical examination, and 78% of those with JDMS had residual dermatologic sequelae. Despite these findings, the mean grade for the group was 4.6 (SD 0.6) for muscle strength, using a scale of 0 to 5 with 0 being no muscle resistance and 5 being normal. In 60% of patients examined by ultrasonography, increased echogenicity indicated possible residual fibrotic change in at least one muscle group. Although MRI showed no active disease process in four patients, scattered intramuscular calcification was found in one patient.

Conclusions: Multiple physical and dermatologic sequelae are commonly present in patients with JDMS/PM on long-term follow-up, but these do not preclude a productive life. Ultrasonography and MRI provide additional noninvasive means of analysis, but because of the current high cost, MRI is not routinely recommended.