Inclusion body myositis presenting as treatment‐resistant polymyositis

Abstract

Inclusion body myositis (IBM) has been viewed as a distinct and rare form of inflammatory myopathy. Previously reported findings from series of IBM patients have suggested that clinical and pathologic features are present which readily distinguish it from idiopathic polymyositis. We report 4 cases of IBM presenting clinically and pathologically as polymyositis, each of which was refractory to therapy. Our data suggest that IBM may be a more common and heterogeneous form of inflammatory myopathy than has been previously suggested. Furthermore, IBM may be clinically and electrophysiologically indistinguishable from polymyositis. Reasons for failing to recognize IBM by pathologic studies appear to include: the skip lesion nature of the pathologic findings, failure to examine tissues by electron microscopy, and a low level of suspicion or lack of recognition. Because of its insidious clinical course and its failure to respond to immunosuppressive therapy, IBM may be an important variant of treatmentresistant polymyositis.

BACE-1, PS-1 and sAPPβ Levels Are Increased in Plasma from Sporadic Inclusion Body Myositis Patients: Surrogate Biomarkers among Inflammatory Myopathies

“…At present, sIBM disease entails two main problems: difficulty for achieving early diagnosis and the lack of effective treatment (7,12,35). The aim of this study was to perform the first screening of circulating molecules potentially involved in the etiopathology of sIBM to promote both advances in understanding the etiology of this disease as well as the development of diagnostic tools.…”

“…The first diagnostic criteria for sIBM were proposed by Calabrese et al (7) in 1987, but so far, muscle biopsy is common myopathy in individuals over 50 years (1). This disease belongs to the group of inflammatory myopathies, together with dermatomyositis (DM)…”

Clinical heterogeneity and treatment response in inclusion body myositis

“…by Calabrese et a1 (9) to the clinical and histologic information available at the time of the initial diagnoses yielded a diagnosis of definite inclusion body myositis in 5 patients and probable inclusion body myositis in the other 5 patients. The clinical features of these 2 groups were similar ( Table 2).…”

“…Calabrese et a1 (9) have proposed preliminary diagnostic criteria for the disease. Definite inclusion body myositis is defined as the presence of filamentous inclusions seen on electron microscopy of muscle tissue, proximal muscle weakness, and 1 of the following features: distal muscle weakness, generalized myopathic changes noted on EMG, elevated creatine phosphokinase (CPK) or aldolase levels, or no clinical improvement of the muscle weakness despite treatment with high-dose steroids.…”

Evaluation and construction of diagnostic criteria for inclusion body myositis

“…Research diagnostic categories for IBM are important in the reporting of research on cohorts of patients with IBM and are essential for the conduct of IBM clinical therapeutic trials. Formal research diagnostic criteria and categories for IBM have been proposed since 1987 by individual authors [1][2][3][4] and through publications of consensus expert opinions developed in 5 meetings in 1995, 5 1996, 6,7 2008, 8 2009, 9 and 2011. 10 These publications have created features (e.g., "presence of quadriceps weakness"), categories (Boolean algebraic combinations of features; e.g., definite), and schemes (combinations of categories; e.g., definite, probable, and possible).…”