{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T12:47:42Z","timestamp":1785934062225,"version":"3.56.0"},"reference-count":16,"publisher":"BMJ","issue":"8","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,7,24]]},"published-print":{"date-parts":[[2026,8]]},"abstract":"<jats:p>Primary hypertrophic osteoarthropathy (PHO) is a rare genetic disorder that closely mimics inflammatory arthritis, leading to diagnostic delays and inappropriate treatment. We report the case of an adolescent boy who presented with a 2-year history of intermittent joint pain and swelling and was initially diagnosed with juvenile idiopathic arthritis at a primary care centre. He was treated with sulfasalazine but experienced only partial symptomatic relief. Laboratory evaluation at the referring centre showed a negative rheumatoid factor and mildly elevated C-reactive protein. Persistent symptoms prompted re-evaluation, which revealed clinical features and a positive family history consistent with PHO. Recognition of characteristic clinical findings and family history led to the correct diagnosis, allowing discontinuation of the disease-modifying anti-rheumatic therapy. This case highlights the importance of considering PHO in the differential diagnosis of chronic arthritis in children, particularly in those with a positive family history.<\/jats:p>","DOI":"10.1136\/bcr-2026-272425","type":"journal-article","created":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T11:55:17Z","timestamp":1785930917000},"page":"e272425","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Rheumatological mimic: primary hypertrophic osteoarthropathy initially treated as juvenile idiopathic arthritis"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0848-6020","authenticated-orcid":false,"given":"Renu","family":"Kumawat","sequence":"first","affiliation":[{"name":"Rheumatology, Indraprastha Apollo Hospitals, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sundeep K","family":"Upadhyaya","sequence":"additional","affiliation":[{"name":"Rheumatology, Indraprastha Apollo Hospitals, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-5340-4999","authenticated-orcid":false,"given":"Disha","family":"Arora","sequence":"additional","affiliation":[{"name":"Rheumatology, Indraprastha Apollo Hospitals, New Delhi, Delhi, India"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,8,5]]},"reference":[{"key":"2026080504551202000_19.8.e272425.1","doi-asserted-by":"publisher","DOI":"10.1002\/humu.22111"},{"key":"2026080504551202000_19.8.e272425.2","doi-asserted-by":"crossref","DOI":"10.1093\/jbmrpl\/ziaf026","article-title":"Primary hypertrophic osteoarthropathy: phenotypic variability and penetrance rate in heterozygotes for SLCO2A1 variants","volume":"9","author":"Arcanjo","year":"2025","journal-title":"JBMR 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