Rinsho Shinkeigaku (Clinical Neurology)

Case Report

Anti-nuclear matrix protein 2 antibody-positive dermatomyositis with the preferential involvement of neck extensors: a case report

Hiroki Fujii, M.D., Ph.D.1), Takashi Kurashige, M.D., Ph.D.2), Satoshi Kubo, M.D., Ph.D.1), Ran Nakashima, M.D., Ph.D.3), Yasuhito Hamaguchi, M.D., Ph.D.4) and Takeshi Kitamura, M.D., Ph.D.1)

1) Department of Neurology, Chugoku Rosai Hospital
2) Department of Neurology, National Hospital Organization Kure Medical Center and Chugoku Cancer Center
3) Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine
4) Department of Dermatology, Kanazawa University Graduate School of Medical Sciences

A 68-year-old man with a 2-month history of progressive weakness and spontaneous pain in proximal limb muscles presented to our hospital with a dropped head. He started experiencing progressive dysphagia several days before admission. On admission, he had muscle weakness of the limbs and neck extensors with edema and induration in distal extremities. Laboratory tests showed elevation of muscle enzymes. FDG-PET/CT demonstrated multiple hypermetabolic lymph nodes, but the primary site was not identified; thus, metastatic carcinoma of unknown primary origin was considered. The patient was diagnosed with anti-nuclear matrix protein 2 antibody-positive paraneoplastic myopathy based on serum tests. Histological findings of the left biceps brachii muscle biopsy revealed severe variation in fiber size and perifascicular myofiber atrophy. Myofibers exhibited myxovirus resistance protein A expression predominantly in the perifascicular region. Following intravenous methylprednisolone pulse therapy and intravenous immunoglobulin, the patient's muscle strength improved with normalization of muscle enzyme levels. The dropped head was considered to have resulted from the preferential involvement of neck extensors based on the observed FDGPET/CT uptake in neck extensors.
Full Text of this Article in Japanese PDF (5192K)

(CLINICA NEUROL, 61: 743−749, 2021)
key words: dropped head syndrome, paraneoplastic myopathy, dermatomyositis, anti-nuclear matrix protein 2 (anti-NXP-2) antibodies, myxovirus resistance protein A (MxA)

(Received: 19-Mar-21)