Background Juvenile dermatomyositis (JDM) is a systemic vasculopathy with proximal muscle weakness and characteristic dermatologic eruptions. The cutaneous histopathology isn’t included in DM criteria, while muscle histopathology is included in it. Recently, amyopathic dermatomyositis in childhood has been recognized to complicate with fatal interstitial pneumonia1). Amyopathic dermatomyositis complicated with interstitial pneumonia has recently been reported even in children. The prognosis of lung manifestation is often poor. Skin biopsy is a very useful method for a diagnosis of amyopathic dermatomyositis.
Objectives The purpose of this study is to evaluate association of clinical findings and features of cutaneous histology in JDM patients.
Methods Fifty-eight patients (17 boys and 41 girls, age at onset 7.5±3.9 years) were diagnosed as JDM at Department of Pediatrics, Yokohama City University Hospital between 1991 and 2010. Skin biopsies from 11 patients (2 boys and 9 girls) were studied by light microscopy and Hematoxylin-eosin stained sections. The Skin biopsy sites determined by dermatologists were thighs (n=3), elbows (n=3), upper arms (n=2), trunk (n=2), the Gottron’s papules of PIP joint (n=1).Clinical manifestations, laboratory findings, and histopathological features were assessed by mainly medical records retrospectively.
Results Ten of eleven patients (91%) had either muscle weakness or elevated serum level of CK. The levels of fibrinogen degradation product-E (FDP-E), markers of endothelial injury, was increased in all cases and the levels of von Willebrand factor were increased in 9/11 cases (n=9, 82%). The High frequency of histological findings are vascular fibrin deposition (n=9, 82%), perivascular lymphocytic infiltration (n=9, 82%), dermal edema (n=9, 82%). The findings were also seen in one patient of amyopathic dermatomyositis with interstitial pneumonia.
Conclusions Subcutaneous and dermal microvascular abnormalities; vascular fibrin depositions, vascular inflammation, of JDM were distinctive findings in this study. The cutaneous histopathology is important for amyopathic dermatomyositis.
Sato S, et al. Curr Opin Rheumatol.2010 Nov; 22(6): 639-43.
Disclosure of Interest None Declared