Necrotizing autoimmune myopathy: Clinicopathologic study from a single tertiary care centre

• Published in: Annals of the Indian Academy of Neurology Vol. 21; no. 1; pp. 62 - 67
• Main Authors: Ayesha, Sobiya, Meena, A, Vangala, Navatha, Rajasekhar, Liza, Kaul, Subhash, Borgahain, Rupam, Uppin, Megha
• Format: Journal Article
• Language: English
• Published: India Wolters Kluwer India Pvt. Ltd 01-01-2018; Medknow Publications and Media Pvt. Ltd; Medknow Publications & Media Pvt. Ltd; Medknow Publications & Media Pvt Ltd; Wolters Kluwer Medknow Publications
• Subjects: 3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase; Adenosine triphosphatase; Antigens; Arthritis; Autoimmune diseases; Biopsy; Cardiovascular disease; Care and treatment; Coenzyme A; Connective tissue diseases; Coronary heart disease; Corticosteroids; Creatinine; Degeneration; Diagnosis; Dosage and administration; Dysphagia; Electromyography; Gangrene; Health risk assessment; Hypothyroidism; Immunoglobulins; Immunotherapy; Inflammation; Inflammatory diseases; Lupus; muscle biopsy; Muscular diseases; Musculoskeletal diseases; Myopathy; Myositis; necrotizing myopathy; Neurology; Original; Pathology; Patients; Phosphatase; Reductase; Scleroderma; signal recognition particle antibodies; Statins; Thyroid gland; Type 2 diabetes; signal recognition particle antibodies; 3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase; muscle biopsy; necrotizing myopathy; statins
• ISSN: 0972-2327; 1998-3549
• DOI: 10.4103/aian.AIAN_389_17

Background: Idiopathic inflammatory myopathies (IIMs) are a group of chronic, autoimmune disorders which include a new entity, necrotizing autoimmune myopathy (NAM). NAM lacks inflammation and presents with markedly elevated creatinine phosphokinase (CPK) levels. It is associated with connective tissue diseases (CTDs), statin use, malignancies, and most cases are idiopathic. Objectives: The objectives of this study are to describe the clinicopathologic features in muscle biopsy-proven cases of NAM. To emphasize the role of laboratory parameters such as CPK levels and myositis profile in the diagnosis of NAM. Materials and Methods: This is a retrospective study including 15 patients of NAM diagnosed on muscle biopsy over a period of 2 years. The slides of the biopsies were reviewed, and clinical data, electromyography findings, and CPK levels were obtained. Myositis profile was done. Results: Necrotizing myopathy accounted for 13.63% (15 cases) of total inflammatory myopathies (110 cases) in the study. These were grouped into CTD-associated NAM, statin-associated NAM, paraneoplastic NAM and idiopathic NAM which was the common type. All cases presented with progressive proximal muscle weakness and had markedly elevated CPK levels. Anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase and antisignal recognition particle antibodies were seen to be positive in six patients. Muscle biopsies showed predominant fiber necrosis with significant fiber degeneration and regeneration in the absence of inflammation. All patients received immunotherapy with significant improvement was seen in six patients with two mortalities. Conclusion: Necrotizing myopathy is a new addition to the spectrum of IIM. Clinicopathologic correlation is important for appropriate diagnosis. It is found to be refractory to corticosteroids monotherapy. The course of illness is not uniform, and in some patients, there can be rapid worsening with mortality.