Clinical significance of subcutaneous fat and fascial involvement in juvenile dermatomyositis

Abstract

Objectives: Subcutaneous involvement, including calcinosis and panniculitis, is a more common complication in juvenile dermatomyositis (JDM) than in adult dermatomyositis. Magnetic resonance imaging (MRI) is useful for evaluating disease distribution. We investigated the clinical significance of subcutaneous involvement in JDM.

Methods: Thighs and hips in 18 newly diagnosed JDM patients were evaluated with fat-suppression MRI. Bilateral muscle, fascial and subcutaneous fat involvement were scored from 0 to 8 points according to the severity of distribution on MRI. Associations between clinical manifestations, serum muscle enzymes, and MRI scores were also evaluated.

Results: Abnormal MRI findings in muscle, fascia and subcutaneous fat were observed in 18, 18, and 10 patients, respectively. Subcutaneous fat scores were significantly higher in early-diagnosed JDM patients (diagnosed less than 2 months from onset) than in late-diagnosed JDM patients (diagnosed later) (p = .025). Serum aldolase was elevated in all patients, although only eight demonstrated elevated serum creatine phosphokinase. Serum aldolase was significantly correlated with MRI scores for subcutaneous fat (p < .0001, ρ = .787) and fascia (p = .013 ρ = 0.574), but not muscle. Additionally, serum aldolase was significantly correlated with serum triglycerides (p = .009, ρ = 0.629).

Conclusion: Subcutaneous fat involvement is a characteristic finding in early-diagnosed JDM and correlates with elevated serum aldolase.

Keywords:

• Aldolase
• fascia
• juvenile dermatomyositis
• MRI
• subcutaneous fat

Acknowledgements

The authors thank Prof. Tomio Inoue (Department of Radiology, Yokohama City University, Yokohama, Japan), Prof. Shumpei Yokota (Department of Pediatrics, Yokohama City University, Yokohama, Japan), Prof. Ichiro Kobayashi (Department of Pediatrics, KKR Sapporo Medical Center, Sapporo, Japan) and Prof. Hiroyuki Tsutsumi (Department of Pediatrics, Sapporo Medical University, Sapporo, Japan) for their great assistance in this study. We thank Richard Robins, PhD, and Nicholas Rufaut, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.

Conflict of interest

Shuichi Ito received unrestricted research grants from Asteras Pharma Co., Ltd. and Pfizer Pharma Co., Ltd. Tokyo Medical and Dental University (TMDU) received unrestricted research grants for the Department of Lifetime Clinical Immunology from AbbVie GK, Ayumi Pharmaceutical Corporation, Chugai Pharmaceutical Co., Ltd., CSL Behring K.K., Japan Blood Products Organization, Mitsubishi Tanabe Pharma Corporation, Nippon Kayaku Co., Ltd., Ono Pharmaceutical Co., Ltd., Towa Pharmaceutical Co., Ltd., and UCB Japan Co. Ltd.; TMDU paid the salary of Masaaki Mori.