{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T17:03:14Z","timestamp":1780074194633,"version":"3.54.0"},"reference-count":27,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T00:00:00Z","timestamp":1780012800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: We report a case of severe dermatomyositis demonstrating characteristic widespread extraosseous uptake on 99mTc-methylene diphosphonate (99mTc-MDP) bone scintigraphy. This study highlights the diagnostic value of this modality in detecting active inflammatory myopathy when conventional muscle biopsy is inconclusive and introduces its novel use for intraoperative gamma-probe-guided biopsy to precisely target metabolically active muscle. This approach may help target metabolically active muscle in heterogeneous idiopathic inflammatory myopathies (IIMs). Case Presentation: A 49-year-old man developed progressive proximal muscle weakness (Medical Research Council grade 2\/5 proximally, 5\/5 distally) beginning in June 2025 following influenza infection, accompanied by dysphagia, classic dermatomyositis cutaneous manifestations, back pain, and difficulty standing. Laboratory evaluation revealed elevated inflammatory markers (ESR 55 mm\/hr, CRP 20 mg\/L), leukocytosis (16.58 \u00d7 109\/L), markedly raised creatine kinase (19,937 IU\/L), and troponin T levels. An initial quadriceps muscle biopsy performed on 29 July 2025 was non-diagnostic. Three-phase 99mTc-MDP scintigraphy (~1110 MBq) demonstrated intense, diffuse extraosseous uptake involving bilateral deltoids (symmetric), biceps and triceps (patchy), paraspinal muscles (longitudinal), gluteal muscles, thighs (quadriceps and hamstrings), and gastrocnemius muscles, with relative suppression of appendicular skeletal uptake on delayed images due to soft-tissue tracer dominance\u2014findings consistent with severe inflammatory myopathy. Following reinjection (~1100 MBq), intraoperative gamma-probe-guided biopsy targeted areas of highest uptake (left quadriceps femoris and distal triceps brachii; intraoperative counts 1300\u20131400 versus background ~500). Histopathology revealed histiocyte-predominant inflammation with myofibre necrosis and regeneration, sparse CD4+ T-cell infiltrates, and absence of fibrosis, consistent with necrotising myopathy. Positive antinuclear antibodies and strong anti-Mi-2 antibodies confirmed the diagnosis of dermatomyositis. Treatment included pulse methylprednisolone followed by oral prednisone taper, methotrexate, azathioprine, intravenous immunoglobulin, and planned rituximab therapy. Discussion: Whole-body 99mTc-MDP scintigraphy provided a complementary whole-body functional assessment of disease extent, revealing widespread muscular involvement. The novel application of intraoperative gamma-probe-guided biopsy enabled real-time targeting of metabolically active muscle, facilitating targeted sampling after an initial non-diagnostic biopsy and yielding supportive histopathological findings. This dual diagnostic and interventional role demonstrates the technical feasibility of gamma-probe guidance in a diagnostically challenging case of dermatomyositis. Conclusions: In our case, the integration of 99mTc-MDP scintigraphy with gamma-probe-guided biopsy enabled precise targeting of metabolically active muscle following an initial non-diagnostic biopsy. This multimodal approach may be useful in selected diagnostically challenging cases of severe inflammatory myopathy. Larger studies are needed to evaluate its reproducibility and added value.<\/jats:p>","DOI":"10.3390\/diagnostics16111684","type":"journal-article","created":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T15:57:18Z","timestamp":1780070238000},"page":"1684","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Extraosseous 99mTc-MDP Uptake Guiding Intraoperative Sampling in Severe Inflammatory Myopathy: A Case Report and Literature Review"],"prefix":"10.3390","volume":"16","author":[{"given":"Masha","family":"Maharaj","sequence":"first","affiliation":[{"name":"Department of Nuclear Medicine, Umhlanga Molecular Imaging & Therapy Centre of Excellence, Netcare Umhlanga Hospital, Umhlanga 4319, KwaZulu-Natal, South Africa"},{"name":"Department of Nuclear Medicine, Loveworld Medical Centre, Lagos 100001, Nigeria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sanvir","family":"Sirriram","sequence":"additional","affiliation":[{"name":"Division of Rheumatology, Department of Internal Medicine, General Justice Mpanza Memorial Regional Hospital, KwaDukuza 4449, KwaZulu-Natal, South Africa"},{"name":"Victoria Hospital, Pietermaritzburg 3201, KwaZulu-Natal, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nav","family":"Govender","sequence":"additional","affiliation":[{"name":"Alberlito Hospital (Private Practice), Ballito 4399, KwaZulu-Natal, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Trisha","family":"Govender","sequence":"additional","affiliation":[{"name":"Department of Nuclear Medicine, Umhlanga Molecular Imaging & Therapy Centre of Excellence, Netcare Umhlanga Hospital, Umhlanga 4319, KwaZulu-Natal, South Africa"},{"name":"Department of Nuclear Medicine, Loveworld Medical Centre, Lagos 100001, Nigeria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Babita D.","family":"Bhana","sequence":"additional","affiliation":[{"name":"Lancet Laboratories, Johannesburg 2092, Gauteng, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nisaar","family":"Korowlay","sequence":"additional","affiliation":[{"name":"Division of Nuclear Medicine, Stellenbosch University, Parow, Cape Town 7505, Western Cape, South Africa"},{"name":"Tygerberg Hospital, Parow, Cape Town 7505, Western Cape, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1734","DOI":"10.1056\/NEJMra1402225","article-title":"Inflammatory muscle diseases","volume":"372","author":"Dalakas","year":"2015","journal-title":"N. Engl. J. Med."},{"key":"ref_2","first-page":"668","article-title":"Classification criteria for polymyositis and dermatomyositis","volume":"22","author":"Tanimoto","year":"1995","journal-title":"J. Rheumatol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"638","DOI":"10.1002\/mus.24566","article-title":"An overview of polymyositis and dermatomyositis","volume":"51","author":"Findlay","year":"2015","journal-title":"Muscle Nerve"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"100018","DOI":"10.1016\/j.jtauto.2019.100018","article-title":"Polymyositis and dermatomyositis\u2014Challenges in diagnosis and management","volume":"2","author":"Yang","year":"2019","journal-title":"J. Transl. Autoimmun."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1016\/S0140-6736(03)14368-1","article-title":"Polymyositis and dermatomyositis","volume":"362","author":"Dalakas","year":"2003","journal-title":"Lancet"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"344","DOI":"10.1056\/NEJM197502132920706","article-title":"Polymyositis and dermatomyositis (first of two parts)","volume":"292","author":"Bohan","year":"1975","journal-title":"N. Engl. J. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1056\/NEJM197502202920807","article-title":"Polymyositis and dermatomyositis (second of two parts)","volume":"292","author":"Bohan","year":"1975","journal-title":"N. Engl. J. Med."},{"key":"ref_8","first-page":"1693","article-title":"Magnetic resonance imaging in the idiopathic inflammatory myopathies","volume":"18","author":"Fraser","year":"1991","journal-title":"J. Rheumatol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1007\/BF03165065","article-title":"Extensive soft-tissue involvement of dermatomyositis detected by whole-body scintigraphy with 99mTc-MDP and 201TL-chloride","volume":"10","author":"Wu","year":"1996","journal-title":"Ann. Nucl. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1007\/s10067-014-2837-2","article-title":"Role of bone scan in the assessment of polymyositis\/dermatomyositis","volume":"34","author":"An","year":"2015","journal-title":"Clin. Rheumatol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1007\/BF02986334","article-title":"Tc-99m MDP bone scintigraphy of myositis as a manifestation of chronic graft-versus-host disease after non-myeloablative peripheral stem cell transplantation","volume":"19","author":"Mitomo","year":"2005","journal-title":"Ann. Nucl. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"595","DOI":"10.1097\/BOR.0b013e32834bab42","article-title":"Acquired immune and inflammatory myopathies: Pathologic classification","volume":"23","author":"Pestronk","year":"2011","journal-title":"Curr. Opin. Rheumatol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"622","DOI":"10.1016\/j.bbadis.2014.05.034","article-title":"Dermatomyositis, polymyositis and immune-mediated necrotising myopathies","volume":"1852","author":"Luo","year":"2015","journal-title":"Biochim. Biophys. Acta."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"550","DOI":"10.3899\/jrheum.120682","article-title":"Classification, diagnosis, and management of idiopathic inflammatory myopathies","volume":"40","author":"Lazarou","year":"2013","journal-title":"J. Rheumatol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/j.nmd.2004.02.006","article-title":"119th ENMC international workshop: Trial design in adult idiopathic inflammatory myopathies, with the exception of inclusion body myositis, 10\u201312 October 2003, Naarden, The Netherlands","volume":"14","author":"Hoogendijk","year":"2004","journal-title":"Neuromuscul. Disord."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1046\/j.1440-1673.2001.00989.x","article-title":"Soft tissue uptake on 99mTc methylene diphosphonate bone scan imaging: Pictorial review","volume":"46","author":"Kaye","year":"2002","journal-title":"Australas. Radiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"715","DOI":"10.1148\/radiographics.13.4.8356264","article-title":"Extraosseous Tc-99m MDP uptake: A pathophysiologic approach","volume":"13","author":"Peller","year":"1993","journal-title":"Radiographics"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1494","DOI":"10.1111\/ene.14027","article-title":"Diagnostic value of additional histopathological fascia examination in idiopathic inflammatory myopathies","volume":"26","author":"Lim","year":"2019","journal-title":"Eur. J. Neurol."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tateyama, M., Fujihara, K., Misu, T., Arai, A., Kaneta, T., and Aoki, M. (2015). Clinical values of FDG PET in polymyositis and dermatomyositis syndromes: Imaging of skeletal muscle inflammation. BMJ Open, 5.","DOI":"10.1136\/bmjopen-2014-006763"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"71","DOI":"10.4103\/ijnm.ijnm_106_21","article-title":"Assessment of Treatment Response by Bone SPECT-CT in a Case of Dermatomyositis with Calcinosis Cutis","volume":"37","author":"Patro","year":"2022","journal-title":"Indian J. Nucl. Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.1097\/00003072-200012000-00012","article-title":"Scintigraphic evaluation of calcinosis in juvenile dermatomyositis with Tc-99m MDP","volume":"25","author":"Mukamel","year":"2000","journal-title":"Clin. Nucl. Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"642","DOI":"10.1016\/j.semarthrit.2016.11.001","article-title":"The role of magnetic resonance imaging techniques in evaluation and management of the idiopathic inflammatory myopathies","volume":"46","author":"Day","year":"2017","journal-title":"Semin. Arthritis Rheum."},{"key":"ref_23","first-page":"39","article-title":"Continuous innovation in precision radio-guided surgery","volume":"43","author":"Cebrecos","year":"2024","journal-title":"Rev. Esp. Med. Nucl. Imagen. Mol."},{"key":"ref_24","unstructured":"National Department of Health (2026, May 20). South African Ethics in Health Research: Principles, Processes and Structures, Available online: https:\/\/www.health.gov.za\/."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"109","DOI":"10.17944\/interdiscip.1699543","article-title":"The clinical features and therapeutic results in patients diagnosed with idiopathic inflammatory myositis: Single center experience","volume":"55","author":"Albayrak","year":"2025","journal-title":"Interdiscip. Med. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1097\/01.md.0000109755.65914.5e","article-title":"Long-term survival of patients with idiopathic inflammatory myopathies according to clinical features: A longitudinal study of 162 cases","volume":"83","author":"Danko","year":"2004","journal-title":"Medicine"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Schiopu, E. (2012). Predictors of survival in a cohort of patients with polymyositis and dermatomyositis: Effect of corticosteroids, methotrexate and azathioprine. Arthritis Res. Ther., 14.","DOI":"10.1186\/ar3704"}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/11\/1684\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T16:04:37Z","timestamp":1780070677000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/11\/1684"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,29]]},"references-count":27,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["diagnostics16111684"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics16111684","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,29]]}}}