{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T14:05:14Z","timestamp":1790863514358,"version":"4.1.0"},"reference-count":31,"publisher":"BMJ","issue":"10","license":[{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,9,4]]},"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:p>A man in his late 70s presented with progressive, painless scrotal swelling. The initial ultrasound was reported as a simple hydrocele, and he was scheduled for surgery. At operation, friable nodules on the tunica vaginalis were biopsied, confirming malignant epithelioid mesothelioma. Staging CT showed no pleural or peritoneal disease, supporting a primary tunica vaginalis origin. As the tunica vaginalis is an embryological continuation of the peritoneum, it is exceptionally rare for mesothelioma to arise here as a true primary rather than as a secondary spread from the peritoneum. This case highlights a rare primary malignant mesothelioma masquerading as a hydrocele, the limitations of ultrasound as a sole diagnostic tool and the importance of maintaining suspicion when operative findings are discordant with imaging.<\/jats:p>","DOI":"10.1136\/bcr-2025-270259","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T13:43:17Z","timestamp":1790862197000},"page":"e270259","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Primary malignant mesothelioma of the tunica vaginalis presenting as hydrocele: imaging pitfalls"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9849-1976","authenticated-orcid":false,"given":"Jatin","family":"Naidu","sequence":"first","affiliation":[{"name":"Medical School, University College London Medical School, London, UK"},{"name":"Division of Surgery and Interventional Science, University College London, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikhil G","family":"Joseph","sequence":"additional","affiliation":[{"name":"Radiology, South Yorkshire and South Humber Deanery, Leeds, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mai","family":"Mohammed","sequence":"additional","affiliation":[{"name":"Cellular Pathology, Kettering General Hospital NHS Foundation Trust, Kettering, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vasanth Kumar","family":"Baskaradoss","sequence":"additional","affiliation":[{"name":"Radiology, Kettering General Hospital NHS Foundation Trust, Kettering, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,10,1]]},"reference":[{"key":"2026100106251715000_19.10.e270259.1","doi-asserted-by":"crossref","first-page":"e6","DOI":"10.1097\/DAD.0000000000002848","article-title":"Metastatic Mesothelioma of the Tunica Vaginalis Presenting as Scrotal and Abdominal Nodules: A Case Report and Review of the Literature","volume":"47","author":"Gilbert","year":"2025","journal-title":"Am J Dermatopathol"},{"key":"2026100106251715000_19.10.e270259.2","doi-asserted-by":"crossref","first-page":"3956","DOI":"10.3390\/cancers16233956","article-title":"Mesothelioma of the Tunica Vaginalis Testis: Diagnostic and Therapeutic Management. 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