Rinsho Shinkeigaku (Clinical Neurology)

Case Report

Appearance of numerous lobulated fibers after a protracted course of 18 years in a case of dermatomyositis

Naoki Onodera, M.D.1), Kazuhito Miyamoto, M.D.1), Shiro Matsubara, M.D.1), Hideaki Hayashi, M.D.1), Narihiro Minami, Ph.D.2) and Ichizo Nishino, M.D.3)

1)Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo
2)National Center of Neurology and Psychiatry, Kodaira, Tokyo
3)Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo

A woman aged 47 first noticed weakness in her proximal muscles of all four limbs at the age of 29. After the initial investigation at our hospital, she was diagnosed as having dermatomyositis associated with primary biliary cirrhosis. In the following 18 years, she was kept on steroids. Although she responded to this treatment, weakness progressed slowly necessitating re-investigation including a second muscle biopsy. It was remarkable that in her first muscle biopsy, no lobulated fiber had been, while they were numerous in the second one. As a result of these studies, possibilities of limb-girdle muscle dystrophy (LGMD) and other myopathies remained but were ultimately ruled out after immunohistochemical/and genetic studies, and the original diagnosis was confirmed. Her weakness responded to an increased dose of steroids. Lobulated fibers were originally described in LGMD, and were reported also in the facioscapulohumeral muscular dytrophy and other hereditary myopathies. They have been rarely described in the inflammatory myopathies. Based on the observation of the present case, we concluded that lobulated fibers have little disease specificity and can newly appear in the course of any chronic myopathies including acquired myopathies like dermatomyositis.

(CLINICA NEUROL, 43: 270－273, 2003)
key words: lobulated fibers, dermatomyositis, the course of chronic myopathies, primary biliary cirrhosis

(Received: 7-Feb-03)