A Case of Anti-NXP2 Antibody-positive Juvenile Dermatomyositis with Characteristic Fascial Thickening on Muscle Ultrasound and Improvement with Immunotherapy

Koji Fukushima; Takeshi Yoshida; Hiroki Yamazaki; Naoko Takamatsu; Takashi Nagai; Yusuke Osaki; Masafumi Harada; Ichizo Nishino; Naoko Okiyama; Kazuma Sugie; Yuishin Izumi

doi:10.2169/internalmedicine.2720-23

A Case of Anti-NXP2 Antibody-positive Juvenile Dermatomyositis with Characteristic Fascial Thickening on Muscle Ultrasound and Improvement with Immunotherapy

Intern Med. 2023 Nov 6. doi: 10.2169/internalmedicine.2720-23. Online ahead of print.

Authors

Affiliations

¹ Department of Neurology, Tokushima University Hospital, Japan.
² Department of Neurology, Nara Medical University School of Medicine, Japan.
³ Department of Rheumatology, Chikamori Hospital, Japan.
⁴ Department of Pediatrics, Tokushima University Hospital, Japan.
⁵ Department of Radiology, Tokushima University Hospital, Japan.
⁶ Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Japan.
⁷ Department of Dermatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan.

PMID: 37926535
DOI: 10.2169/internalmedicine.2720-23

Abstract

We herein report a 12-year-old boy who presented with a fever, erythematous rash on the cheeks, back pain, and dysphagia. Blood tests revealed increased creatine kinase levels, and muscle ultrasonography (MUS) revealed characteristic fascial thickening in the lumbar paraspinal muscles, where myalgia was prominent. Sarcoplasmic expression of myxovirus-resistant protein A on a muscle biopsy and the presence of anti-nuclear matrix protein 2 (NXP2) antibodies confirmed the diagnosis of dermatomyositis. Prednisolone and intravenous immunoglobulin therapy improved the clinical and laboratory parameters as well as fascial thickening. MUS is useful for evaluating fasciitis associated with anti-NXP2 autoantibodies and monitoring therapeutic efficacy.

Keywords: Dermatomyositis sine dermatitis; Fasciitis; Juvenile dermatomyositis; Muscle ultrasound; Myxovirus resistant protein A; Nuclear matrix protein 2.