The Inflammatory Myopathies. Lawrence J. Kagen ed. Humana Press 2009, 342 pages, 151 illustrations, $99.00.
Inflammatory myopathies encompass a rare and broad group of diseases affecting both children and adults, with widely differing risk factors, outcomes, and histopathologic findings. The most common diseases are polymyositis, dermatomyositis and inclusion body myositis; however rarer entities such as cancer-associated, granulomatous, eosinophilic and vasculitic myositis have been described. They are all characterized clinically by muscle weakness and histologically by immune-mediated mononuclear inflammatory infiltrates within skeletal muscle. Different cytokines and chemokines with varying hypothetical roles have been identified within affected tissues, resulting in muscle inflammation, necrosis and atrophy.
Even though recent advances have resulted in a better understanding these disorders, their pathogenesis remains obscure and their diagnosis often delayed. The classification, diagnosis and treatment of the individual diseases is challenging and controversial, with a number of competing approaches presently employed. Therapeutic problems arise from the difficulty in distinguishing myopathies that are responsive to treatment from more difficult-to-treat mimics. Regardless of the classification criteria used, a number of patients still defy diagnosis necessitating empirical treatment. It is therefore vital to interpret the interrelationships of critical disease features in order to develop more effective treatments and improve patient outcomes. That is the purpose of this text.
This book provides a comprehensive review of the most common and uncommon inflammatory myopathies in eighteen well organized chapters, including a step-by-step review of the skeletal and extra-skeletal manifestations, diagnostic criteria, environmental risk factors, and treatment outcomes. Each chapter is written by an expert in a different medical field; including radiology, rheumatology, rehabilitation, dermatology and physical therapy. The latest information on the pathogenesis of these diseases, along with emerging molecular and cellular targets for possible future therapeutic interventions is presented. The most common clinicopathologic, serologic, and genetic classifications schemes are discussed, their problems delineated, and areas of disease categorization overlap addressed. Characteristic muscle biopsy findings are offered in high quality electron microscopy pictures. Pathologic basis and distinguishing findings of electrodiagnostic studies are identified, and the many different technical factors influencing the diagnostic accuracy of these tests are addressed. Different drug therapies are discussed, including the use of corticosteroids and immunosuppressive agents such as methotrexate, cyclophosphamide, and tumor necrosis alpha, as well as other treatment options such as plasma exchange.
Of particular interest to radiologists will be the chapters discussing the magnetic resonance imaging (MRI) and sonographic findings of the inflammatory myopathies. Non-invasive imaging plays a critical role in the assessment of disease activity, effectiveness of therapy and course of illness. While often nonspecific, imaging findings play a critical role in identifying affected muscles and therefore providing cost-effective guidance for muscle biopsy by decreasing false-negative biopsy rates, as well as lowering the incidence of repeat biopsies. This is particularly important in patients whose imaging abnormalities precede the clinical manifestations of their disease. In addition, MRI provides a non-invasive means of assessing the longitudinal course and disease progression or regression of myopathies, as well as differentiating inflammatory from infectious myopathies in vulnerable populations such as HIV positive patients. Functional MRI holds promise in allowing a detailed molecular analysis of affected tissue, which someday may provide additional differentiating features. Newer sonographic applications, including power Doppler sonography, contrast-enhanced ultrasound and sonoelastography are presented, and their future possible roles addressed. Later chapters discuss muscle strength and exercise programs for patients with inflammatory myopathies, the risk of malignancy in patients with dermatomyositis and polymyositis. Radiologists, rheumatologists, neurologists and other healthcare professionals involved in the treatment in afflicted patients should find this book very useful and informative.
