{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T12:47:01Z","timestamp":1785934021076,"version":"3.56.0"},"reference-count":15,"publisher":"BMJ","issue":"8","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,7,27]]},"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:p>Dermatomyositis (DM) and hypothyroid myopathy are both treatable causes of muscle weakness and can present with overlapping clinical and laboratory features, posing a diagnostic challenge. We report the case of a young male who presented with proximal upper and lower limb muscle weakness, calf muscle hypertrophy and elevated serum creatine kinase (CK) and was found to have hypothyroidism. Muscle weakness and hyperCKemia persisted despite normalisation of thyroid function, prompting a muscle biopsy and extended autoantibody testing, which revealed anti-Ku-positive DM characterised by perivascular inflammation, perifascicular atrophy and membrane attack complex deposition. High-dose corticosteroids led to partial improvement and subsequent rituximab therapy achieved sustained clinical and biochemical remission. This case emphasises the importance of considering dual aetiology when appropriate treatment of the primary diagnosis does not yield expected results. Early biopsy and comprehensive serological evaluation could lead to excellent clinical outcomes.<\/jats:p>","DOI":"10.1136\/bcr-2025-271331","type":"journal-article","created":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T11:55:19Z","timestamp":1785930919000},"page":"e271331","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Unmasking dermatomyositis in a patient with hypothyroid myopathy"],"prefix":"10.1136","volume":"19","author":[{"given":"Sagar","family":"Poudel","sequence":"first","affiliation":[{"name":"Department of Neurology, All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Siddharth","family":"Jain","sequence":"additional","affiliation":[{"name":"Department of Medicine, All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mehar Chand","family":"Sharma","sequence":"additional","affiliation":[{"name":"Pathology, All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Swati","family":"Mahajan","sequence":"additional","affiliation":[{"name":"All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rajesh","family":"Khadgawat","sequence":"additional","affiliation":[{"name":"Department of Endocrinology, All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0128-7037","authenticated-orcid":false,"given":"Arunmozhimaran","family":"Elavarasi","sequence":"additional","affiliation":[{"name":"Department of Neurology, All India Institute of Medical Sciences, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,8,5]]},"reference":[{"key":"2026080504550961000_19.8.e271331.1","doi-asserted-by":"crossref","first-page":"1033","DOI":"10.1089\/thy.1998.8.1033","article-title":"Myopathy as the persistently isolated symptomatology of primary autoimmune hypothyroidism","volume":"8","author":"Rodolico","year":"1998","journal-title":"Thyroid"},{"key":"2026080504550961000_19.8.e271331.2","doi-asserted-by":"publisher","DOI":"10.1007\/s11154-016-9357-0"},{"key":"2026080504550961000_19.8.e271331.3","doi-asserted-by":"crossref","unstructured":"Jervis W , Shah N , Mongolu SK , et al . Severe proximal myopathy secondary to Hashimoto\u2019s thyroiditis. BMJ Case Rep 2019;12. doi:10.1136\/bcr-2019-230427","DOI":"10.1136\/bcr-2019-230427"},{"key":"2026080504550961000_19.8.e271331.4","doi-asserted-by":"crossref","first-page":"e200","DOI":"10.1097\/RHU.0000000000001395","article-title":"Anti-Ku Antibody-Related Scleroderma-Polymyositis Overlap Syndrome Associated With Hypothyroid Myopathy","volume":"27","author":"Kadowaki","year":"2021","journal-title":"J Clin Rheumatol"},{"key":"2026080504550961000_19.8.e271331.5","doi-asserted-by":"crossref","unstructured":"Garg A , Helbig M , Schauer M , et al . A Complex Case of Polymyositis Overlapping With Hypothyroid Myopathy Without Underlying Autoimmune Thyroid Disorder. Cureus 2020;12. doi:10.7759\/cureus.8629","DOI":"10.7759\/cureus.8629"},{"key":"2026080504550961000_19.8.e271331.6","doi-asserted-by":"crossref","first-page":"447","DOI":"10.4103\/0976-3147.140025","article-title":"Hoffman\u2019s syndrome - A rare facet of hypothyroid myopathy","volume":"5","author":"Mangaraj","year":"2014","journal-title":"J Neurosci Rural Pract"},{"key":"2026080504550961000_19.8.e271331.7","doi-asserted-by":"publisher","DOI":"10.1007\/s10067-005-1165-y"},{"key":"2026080504550961000_19.8.e271331.8","doi-asserted-by":"publisher","DOI":"10.1089\/10507250252949478"},{"key":"2026080504550961000_19.8.e271331.9","doi-asserted-by":"publisher","DOI":"10.1080\/08916930500050194"},{"key":"2026080504550961000_19.8.e271331.10","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1016\/j.semarthrit.2021.04.012","article-title":"The phenotype of myositis patients with anti-Ku autoantibodies","volume":"51","author":"Casal-Dominguez","year":"2021","journal-title":"Semin Arthritis Rheum"},{"key":"2026080504550961000_19.8.e271331.11","doi-asserted-by":"publisher","DOI":"10.1111\/j.1468-3083.2010.03929.x"},{"key":"2026080504550961000_19.8.e271331.12","doi-asserted-by":"crossref","unstructured":"Qiao L , Lin Y , Liu M , et al . The clinical features, muscle pathology, and role of autophagy in anti-Ku-positive patients. Front Immunol 2025;16. doi:10.3389\/fimmu.2025.1608735","DOI":"10.3389\/fimmu.2025.1608735"},{"key":"2026080504550961000_19.8.e271331.13","doi-asserted-by":"crossref","unstructured":"Oyama M , Holzer M-T , Ohnuki Y , et al . Pathologic Features of Anti-Ku Myositis. Neurology 2024;102. doi:10.1212\/WNL.0000000000209268","DOI":"10.1212\/WNL.0000000000209268"},{"key":"2026080504550961000_19.8.e271331.14","doi-asserted-by":"publisher","DOI":"10.1007\/s13317-014-0062-2"},{"key":"2026080504550961000_19.8.e271331.15","doi-asserted-by":"crossref","first-page":"952","DOI":"10.1002\/mus.880131011","article-title":"Central changes in hypothyroid myopathy: a case report","volume":"13","author":"Evans","year":"1990","journal-title":"Muscle Nerve"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr-2025-271331","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T11:55:21Z","timestamp":1785930921000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr-2025-271331"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8]]},"references-count":15,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8,5]]},"published-print":{"date-parts":[[2026,8]]}},"alternative-id":["10.1136\/bcr-2025-271331"],"URL":"https:\/\/doi.org\/10.1136\/bcr-2025-271331","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8]]}}}