{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T14:16:58Z","timestamp":1771251418273,"version":"3.50.1"},"reference-count":6,"publisher":"Oxford University Press (OUP)","issue":"2","license":[{"start":{"date-parts":[[2026,1,30]],"date-time":"2026-01-30T00:00:00Z","timestamp":1769731200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,2,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Primary malignant pericardial tumours are extremely rare, and synovial sarcoma arising from the pericardium is an exceptionally uncommon entity with poor survival. Diagnosis is often delayed because initial pericardial biopsies can be non-diagnostic, and distinguishing between inflammatory disease and malignancy may be challenging.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case summary<\/jats:title>\n                    <jats:p>An 11-year-old boy developed recurrent fever and chest pain 15 days after Coronavirus disease 2019 infection. Echocardiography demonstrated pericardial effusion, and pericarditis was suspected. Despite drainage of haemorrhagic effusion, pericardial biopsy showed only fibrous thickening. Two months later, recurrent effusion and haematoma enlargement prompted repeat evaluation, but multimodal imaging including computed tomography, magnetic resonance imaging, and catheterization failed to identify the aetiology. At 3 months, worsening haematoma around the left ventricular posterior wall necessitated surgical excision. The mass was tightly adherent to the pericardium, precluding complete resection. Histology revealed spindle-shaped tumour cells, and molecular testing confirmed SS18::SSX fusion, leading to a diagnosis of synovial sarcoma. 18F-fluorodeoxyglucose positron emission tomography\/computed tomography (18F-FDG PET\/CT) showed pericardial uptake without distant disease. The patient underwent chemotherapy, radiotherapy, and high-dose chemotherapy with autologous stem cell rescue. He remained in remission for 18 months, but subsequently developed brain metastases and died.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>This case highlights the diagnostic difficulty of primary pericardial synovial sarcoma. Initial biopsy may be falsely negative, and repeated sampling directly from the lesion is crucial when a cardiac tumour is suspected. Furthermore, 18F-FDG PET\/CT proved valuable not only for diagnostic assessment but also for therapeutic monitoring. In summary, repeated targeted biopsy and multimodality imaging are essential for accurate diagnosis and management of this rare cardiac malignancy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/ehjcr\/ytag072","type":"journal-article","created":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T12:44:51Z","timestamp":1769690691000},"source":"Crossref","is-referenced-by-count":0,"title":["Primary synovial sarcoma of the pericardium diagnosed after multiple biopsies following recurrent episodes of haemorrhagic pericardial effusion following infection: a case report"],"prefix":"10.1093","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5728-8867","authenticated-orcid":false,"given":"Masayoshi","family":"Mori","sequence":"first","affiliation":[{"name":"Department of Cardiology, Osaka Women\u2019s and Children\u2019s Hospital , 840 Murodo-cho, Izumi, Osaka 594-1101 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6065-133X","authenticated-orcid":false,"given":"Yoichiro","family":"Ishii","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Osaka Women\u2019s and Children\u2019s Hospital , 840 Murodo-cho, Izumi, Osaka 594-1101 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yosuke","family":"Okada","sequence":"additional","affiliation":[{"name":"Department of Hematology and Oncology, Osaka Women\u2019s and Children\u2019s Hospital , Osaka 594-1101 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Makoto","family":"Takeuchi","sequence":"additional","affiliation":[{"name":"Department of Pathology, Osaka Women\u2019s and Children\u2019s Hospital , Osaka 594-1101 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3083-4597","authenticated-orcid":false,"given":"Hisaaki","family":"Aoki","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Osaka Women\u2019s and Children\u2019s Hospital , 840 Murodo-cho, Izumi, Osaka 594-1101 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"286","published-online":{"date-parts":[[2026,1,30]]},"reference":[{"key":"2026021608365831900_ytag072-B1","doi-asserted-by":"crossref","first-page":"2117","DOI":"10.1038\/s41591-022-02000-0","article-title":"Long-term cardiac pathology in individuals with mild initial COVID-19 illness","volume":"28","author":"Puntmann","year":"2022","journal-title":"Nat Med"},{"key":"2026021608365831900_ytag072-B2","first-page":"3","article-title":"Recurrent haemorrhagic pericardial effusion due to idiopathic pericarditis: a case report","volume":"25","author":"Rivero","year":"2019","journal-title":"Eur Heart J Case Rep"},{"key":"2026021608365831900_ytag072-B3","first-page":"213","volume-title":"WHO Classification of Tumours of Soft Tissue and Bone","author":"Suurmeijer","year":"2013"},{"key":"2026021608365831900_ytag072-B4","doi-asserted-by":"crossref","first-page":"1321","DOI":"10.1111\/jocs.14214","article-title":"Primary cardiac synovial sarcoma: a review correlating outcomes with surgery and adjuvant therapy","volume":"34","author":"Coli","year":"2019","journal-title":"J Card Surg"},{"key":"2026021608365831900_ytag072-B5","first-page":"589.e17","article-title":"Pericardial sarcoma: \u201cinvisible\u201d on radiology","volume":"36","author":"Wei","year":"2020","journal-title":"Can J Cardiol Case Rep"},{"key":"2026021608365831900_ytag072-B6","doi-asserted-by":"crossref","first-page":"856","DOI":"10.2967\/jnumed.111.095364","article-title":"Differentiation of malignant and benign cardiac tumors using 18F-FDG PET\/CT","volume":"53","author":"Rahbar","year":"2012","journal-title":"J Nucl Med"}],"container-title":["European Heart Journal - 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