P. Treadwell et al. (eds.)Atlas of Adolescent Dermatologyhttps://doi.org/10.1007/978-3-030-58634-8_16

16. Juvenile Dermatomyositis

Patricia Treadwell¹

(1)

Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA

Patricia Treadwell

Email: ptreadwe@iupui.edu

Keywords

Juvenile Dermatomyositis (JDMS)Gottron’s papulesMuscle weakness

16.1 Introduction

Juvenile dermatomyositis (JDMS) is a rare inflammatory disorder affecting skin and muscle.

16.2 Epidemiology

JDMS can begin in adolescence; however, peak incidence is 5–10 years of age occurring 2–4 cases per million children each year. The male to female ratio is 1:2–5.

16.3 Clinical Findings

Clinical findings show characteristic violaceous discoloration of the eyelids (heliotrope) (Fig. 16.1), erythematous scaly papules of the dorsal hands overlying the MCP and PIP joints (Gottron’s papules) (Fig. 16.2), and other parts of the body (Fig. 16.3). In some cases, calcinosis may develop. Capillary dilatation is noted in the periungual areas with some capillary dropout. Symmetrical proximal muscle weakness is also noted. Parents may report photosensitivity and/or worsening of the cutaneous findings with sun exposure.

../images/446896_1_En_16_Chapter/446896_1_En_16_Fig1_HTML.jpg — Fig. 16.1
Heliotrope: violaceous discoloration of the upper eyelid

../images/446896_1_En_16_Chapter/446896_1_En_16_Fig2_HTML.jpg — Fig. 16.2
Gottron’s papules noted on the dorsal hands overlying the joints

../images/446896_1_En_16_Chapter/446896_1_En_16_Fig3_HTML.jpg — Fig. 16.3
JDMS calcinosis of the elbows

16.4 Laboratory

Laboratory evaluation shows elevated muscle enzymes (serum aldolase, AST, CPK, and LDH). Skin biopsies are nonspecific with perivascular inflammation.

MRI has been used for diagnosis and for monitoring disease activity. The T2, fc-T2 (fat corrected T2), and FF (fat fraction) measurements are helpful in JDMS to distinguish those MRI findings that may also be seen in other myopathies. EMG and muscle biopsy are less often used because of the invasiveness. Muscle biopsies when they are performed can be guided by MRI – since the muscle involvement can be unevenly distributed.

16.5 Treatment

The medications used most often for JDMS are glucocorticosteroids, methotrexate, cyclosporin A, and IVIG. Other immunosuppressive agents have also been used in more refractory cases. Biologics have occasionally been used. Sun protection and physical therapy are also recommended.

16.6 Prognosis

The mortality rate of JDMS is less than 2%. JDMS is generally not associated with malignancy (in contrast to adult DM), and an occult malignancy work-up is not recommended.