Rinsho Shinkeigaku (Clinical Neurology)

Brief Clinical Note

A case of dermatomyositis positive for anti-nuclear matrix protein 2 antibody without dermatologic symptoms

Eriko Takeuchi, M.D.1)2), Daisuke Hirozawa, M.D., Ph.D.1), Naoko Okiyama, M.D., Ph.D.3), Michio Inoue, M.D., Ph.D.4), Ichizo Nishino, M.D., Ph.D.4) and Fuminobu Sugai, M.D., Ph.D.1)

1) Department of Neurology, Otemae Hospital
2) Present address: Department of Neurology and Cerebrovascular Disease, Osaka University Hospital
3) Department of Dermatology, Faculty of Medicine, University of Tsukuba
4) Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry

We report a 47-year-old woman who presented with progressive myalgia, weakness in the proximal limbs, and dysphagia for a month and a half. No skin rash was observed on admission. Examination of MRI data suggested inflammatory changes in the proximal limbs and trunk muscles. Biopsy specimens from the left biceps muscle showed no perifascicular atrophy, but immunohistochemical staining revealed the presence of myxovirus resistance protein A (MxA) in myofibers, strongly suggesting dermatomyositis (DM). In addition, her serum was positive for anti-nuclear matrix protein 2 (anti-NXP-2) antibody, which is reportedly useful as a marker of DM without skin lesions. Her symptoms gradually improved upon intravenous methylprednisolone pulse therapy in conjunction with oral prednisolone, oral tacrolimus, and intravenous immunoglobulin therapy. Our findings suggest that in cases where inflammatory muscle disease is suspected, anti-NXP-2 antibody analyses should be considered for precise diagnosis, even if there are no dermatological symptoms.
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(CLINICA NEUROL, 61: 258−261, 2021)
key words: dermatomyositis without skin lesions, anti-nuclear matrix protein 2 (anti-NXP-2) antibody, myxovirus resistance protein A (MxA), myositis-specific autoantibodies

(Received: 5-Aug-20)