{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T13:04:47Z","timestamp":1776776687637,"version":"3.51.2"},"reference-count":38,"publisher":"BMJ","issue":"4","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,4,2]]},"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:p>\n                    A female in her early 30s presented with worsening right knee pain with atraumatic onset. Imaging revealed a heterogeneous, contrast-enhancing, T1 hypointense mass in the retropatellar fat pad. Initial differential diagnosis favoured localised tenosynovial giant cell tumour. Malignancy was also considered. These alternative pathologies require more aggressive treatment modalities and demonstrate significant recurrence rates. The patient ultimately underwent open excision and histological analysis which revealed intra-articular nodular fasciitis (NF). Detection of ubiquitin-specific protease 6 (\n                    <jats:italic>USP6<\/jats:italic>\n                    ) on histopathological analysis was crucial in establishing diagnosis. At the final follow-up, knee extension had improved, she was ambulating without aids, and she had returned to work. Our case emphasises that intra-articular NF is a rare entity that can mimic more common intra-articular tumours. The detection of\n                    <jats:italic>USP6<\/jats:italic>\n                    on histopathological analysis allows accurate diagnosis and treatment.\n                  <\/jats:p>","DOI":"10.1136\/bcr-2025-271515","type":"journal-article","created":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T12:15:21Z","timestamp":1776773721000},"page":"e271515","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Nodular fasciitis with intra-articular presentation within the knee"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1008-727X","authenticated-orcid":false,"suffix":"III","given":"Robert Raymond","family":"Hall","sequence":"first","affiliation":[{"name":"Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steven","family":"Baccei","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nupur","family":"Jadhav","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9050-1148","authenticated-orcid":false,"given":"Mathew J","family":"Most","sequence":"additional","affiliation":[{"name":"Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2026,4,21]]},"reference":[{"key":"2026042105151126000_19.4.e271515.1","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1111\/ijd.14219","article-title":"Nodular fasciitis, a forgotten entity","volume":"58","author":"Luna","year":"2019","journal-title":"Int J Dermatol"},{"key":"2026042105151126000_19.4.e271515.2","doi-asserted-by":"publisher","DOI":"10.1093\/ajcp\/25.3.241"},{"key":"2026042105151126000_19.4.e271515.3","doi-asserted-by":"publisher","DOI":"10.1001\/archderm.1966.01600200060009"},{"key":"2026042105151126000_19.4.e271515.4","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1016\/j.anndiagpath.2015.03.013","article-title":"Nodular fasciitis: a retrospective study of 272 cases from China with clinicopathologic and radiologic correlation","volume":"19","author":"Lu","year":"2015","journal-title":"Ann Diagn Pathol"},{"key":"2026042105151126000_19.4.e271515.5","doi-asserted-by":"crossref","DOI":"10.1136\/bcr-2014-207727","article-title":"Nodular fasciitis of the masseter","volume":"2015","author":"Babu","year":"2015","journal-title":"BMJ Case Rep"},{"key":"2026042105151126000_19.4.e271515.6","doi-asserted-by":"crossref","unstructured":"Montreuil J , Campano D , Montoya-Cerrillo D , et al . 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