{"id":239,"date":"2017-12-14T15:06:04","date_gmt":"2017-12-14T20:06:04","guid":{"rendered":"http:\/\/www.myositis.org\/about-myositis\/types-of-myositis\/necrotizing-myopathy\/"},"modified":"2025-05-30T12:48:16","modified_gmt":"2025-05-30T16:48:16","slug":"necrotizing-myopathy","status":"publish","type":"page","link":"https:\/\/www.myositis.org\/about-myositis\/types-of-myositis\/necrotizing-myopathy\/","title":{"rendered":"Immune-Mediated Necrotizing Myopathy"},"content":{"rendered":"<div class=\"wp-block-image\">\n<figure class=\"alignleft size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"296\" height=\"700\" src=\"https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back-296x700.jpg\" alt=\"\" class=\"wp-image-23711\" style=\"width:138px;height:auto\" srcset=\"https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back-296x700.jpg 296w, https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back-127x300.jpg 127w, https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back-300x710.jpg 300w, https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back-34x80.jpg 34w, https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/Body_PM-DM-back.jpg 400w\" sizes=\"auto, (max-width: 296px) 100vw, 296px\" \/><figcaption class=\"wp-element-caption\">INMN causes symetrical, proximal muscle weakness<\/figcaption><\/figure><\/div>\n\n\n<p>Immune-mediated necrotizing myopathy (IMNM)\u2014also referred to as necrotizing autoimmune myopathy (NAM) or necrotizing myopathy (NM)\u2014is an inflammatory muscle disease that involves necrosis, or cell death, in the muscles, which causes symmetrical (on both sides of the body) muscle weakness.<\/p>\n\n\n\n<p>Immune-mediated necrotizing myopathy primarily affects&nbsp;proximal muscles, that is, the muscles closest to the center of the body. Onset is relatively quickly, happening over days, weeks, or months, and usually occurs in adults between the ages of 40 and 60.<\/p>\n\n\n\n<p>As with other types of myositis, there is no known cause or cure for necrotizing myopathy. However, <a href=\"https:\/\/www.myositis.org\/about-myositis\/treatment-disease-management\/\" target=\"_blank\" rel=\"noreferrer noopener\">treatments<\/a> are available that can successfully manage symptoms.<\/p>\n\n\n\n<div style=\"height:23px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Signs and symptoms<\/h2>\n\n\n\n<p>Those with necrotizing myopathy may experience the following symptoms:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Weakness in the muscles closest to the center of the body, like the shoulders, forearms, hips, thighs, neck, and back<\/li>\n\n\n\n<li>Difficulty climbing stairs and standing up from a chair<\/li>\n\n\n\n<li>Difficulty lifting arms over the head<\/li>\n\n\n\n<li>Falling and difficulty getting up from a fall<\/li>\n\n\n\n<li>Shortness of breath and\/or chronic dry cough<\/li>\n\n\n\n<li>Difficulty swallowing (<a href=\"https:\/\/www.myositis.org\/about-myositis\/complications\/dysphagia\/\" target=\"_blank\" rel=\"noreferrer noopener\">dysphagia<\/a>)<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Disassociated from polymyositis<\/h2>\n\n\n\n<p>Necrotizing myopathy is a distinct subset of <a href=\"https:\/\/rarediseases.info.nih.gov\/diseases\/9128\/idiopathic-inflammatory-myopathy\" target=\"_blank\" rel=\"noreferrer noopener\">idiopathic inflammatory myopathy<\/a>, or myositis. Patients with necrotizing myopathy have muscle biopsies characterized by predominant necrosis (i.e., death) of muscle cells with often less inflammation than other myositis subsets.<\/p>\n\n\n\n<p>Before necrotizing myopathy was recognized as a separate entity, many patients with necrotizing myopathies were labelled as polymyositis, because both subsets share similar clinical features. However, specific autoantibodies (for example, anti-HMGCR) and muscle biopsy features can help physicians differentiate those diseases.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Categories of necrotizing myopathies<\/h2>\n\n\n\n<p>There are different categories of necrotizing myopathies characterized by distinct risk factors and disease course. These categories are mainly differentiated based on <a href=\"https:\/\/www.myositis.org\/about-myositis\/diagnosis\/blood-tests\/myositis-autoantibodies\/\" target=\"_blank\" rel=\"noreferrer noopener\">autoantibodies<\/a> measured in the patient\u2019s blood.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Patients with anti-SRP autoantibodies<\/h3>\n\n\n\n<p>Anti-signal recognition particle (SRP) autoantibodies are found in some patients with necrotizing myopathies. Their presence are often associated with severe muscle weakness and difficulty swallowing. Inflammation of the lungs and heart can also be seen in that subset.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Patients with anti-HMGCR autoantibodies<\/h3>\n\n\n\n<p>HMGCR (3-hydroxy-3-methylglutaryl-coenzyme A reductase) is a key enzyme in the production of cholesterol. Some patients exposed to HMGCR inhibitors for cholesterol treatment (that is, statins) or through dietary sources (for example, red yeast rice and oyster mushrooms) can develop anti-HMGCR autoantibodies. Sometimes, however, no environmental triggers are found to explain their presence. Anti-HMGCR positive necrotizing myopathies usually present with mainly severe muscle symptoms. <\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Patients with no autoantibodies<\/strong><\/h3>\n\n\n\n<p>Patients with necrotizing myopathies without anti-SRP or -HMGCR autoantibodies in their blood are considered by some experts to be included in a separate, third grouping of necrotizing myopathies called seronegative.<\/p>\n\n\n\n<p>If you are experiencing muscle symptoms involving weakness or fatigue, we encourage you to talk to your doctor to begin the diagnosis process, which includes a <a href=\"https:\/\/www.myositis.org\/about-myositis\/diagnosis\/muscle-skin-biopsy\/\" target=\"_blank\" rel=\"noreferrer noopener\">muscle biopsy<\/a> to detect necrosis and various <a href=\"https:\/\/www.myositis.org\/about-myositis\/diagnosis\/blood-tests\/\" target=\"_blank\" rel=\"noreferrer noopener\">blood tests<\/a> to detect the presence of autoantibodies. Since necrotizing myopathy is a rare disease, many physicians may not be familiar with the signs and symptoms. If you are struggling to find an accurate diagnosis, <a href=\"https:\/\/www.myositis.org\/patient-support\/find-doctor\/\" target=\"_blank\" rel=\"noreferrer noopener\">visiting a specialist<\/a> can help.<\/p>\n\n\n\n<p><em>Revised April 2025 by Val\u00e9rie Leclair, MD, PhD \u2013 rheumatologist, research scientist, and TMA medical advisor<\/em><\/p>\n\n\n\n<p>See: <strong>Pinal-Fernandez I, Casal Dominguez M, Mammen A.<\/strong> <a href=\"https:\/\/www.myositis.org\/wp-content\/uploads\/2025\/05\/2018-Immune-Mediated-Necrotizing-Myopathy-Pinal-Fernandez-Current_Rheumatology_Reports.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Immune-Mediated Necrotizing Myopathy<\/a>. <em>Current Rheumatology Reports,<\/em> 2018. 20(4). DOI:10.1007\/s11926-018-0732-6<\/p>\n\n\n\n<p><em><strong>Disclaimer<\/strong>: Information provided on this website is for&nbsp;<strong>educational purposes only<\/strong>&nbsp;and is&nbsp;<strong>not a substitute for professional medical advice, diagnosis, or treatment<\/strong>. Always consult a qualified healthcare provider with any questions you may have regarding a medical condition.<\/em><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Immune-mediated necrotizing myopathy (IMNM)\u2014also referred to as necrotizing autoimmune myopathy (NAM) or necrotizing myopathy (NM)\u2014is an inflammatory muscle disease that involves necrosis, or cell death, in the muscles, which causes&#8230;<\/p>\n","protected":false},"author":189,"featured_media":0,"parent":235,"menu_order":79,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-239","page","type-page","status-publish","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.1.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Immune-Mediated Necrotizing Myopathy - The Myositis Association<\/title>\n<meta name=\"description\" content=\"Necrotizing myopathy is a newly defined form of myositis, characterized by necrosis in the muscles. 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