{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T12:19:13Z","timestamp":1788437953768,"version":"build-2803163510"},"reference-count":20,"publisher":"BMJ","issue":"5","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,4,23]]},"published-print":{"date-parts":[[2026,5]]},"abstract":"<jats:p>Collision tumours of the thyroid are rare, accounting for less than 1% of all thyroid malignancies. They represent the coexistence of two histologically distinct but adjacent and morphologically independent tumours, most commonly papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC). We report a case of a diabetic male in his fourth decade of life who presented with neck swelling. Imaging revealed a bulky left thyroid lobe with lymph node involvement. Fine-needle aspiration cytology suggested PTC with lymph node metastasis. However, histopathology following total thyroidectomy, paratracheal dissection and left functional neck dissection revealed a collision tumour comprising both PTC and MTC. Postoperative management included radioiodine therapy, Ga-68 DOTANOC (1,4,7,10-tetraazacyclododecane-tetraacetic acid 1-Nal3-octreotide) scan and external beam radiotherapy. In such cases, the prognosis largely depends on the more aggressive component, typically MTC. The serial monitoring of serum calcitonin and thyroglobulin levels and appropriate imaging are essential for follow-up. Owing to the rarity and complexity of these tumours, multimodal treatment should be considered.<\/jats:p>","DOI":"10.1136\/bcr-2025-267185","type":"journal-article","created":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T12:30:20Z","timestamp":1779971420000},"page":"e267185","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Collision thyroid tumour"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-9872-0819","authenticated-orcid":false,"given":"Vishal","family":"Kalshetty","sequence":"first","affiliation":[{"name":"Surgery, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Harish","family":"K","sequence":"additional","affiliation":[{"name":"Oncosurgery, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,5,27]]},"reference":[{"key":"2026090305051104000_19.5.e267185.1","doi-asserted-by":"publisher","DOI":"10.22551\/2021.33.0804.10191"},{"key":"2026090305051104000_19.5.e267185.2","doi-asserted-by":"crossref","DOI":"10.3390\/cancers11101516","article-title":"Epidemiology of Simultaneous Medullary and Papillary Thyroid Carcinomas (MTC\/PTC): An Italian Multicenter Study","volume":"11","author":"Appetecchia","year":"2019","journal-title":"Cancers (Basel)"},{"key":"2026090305051104000_19.5.e267185.3","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1007\/s12070-011-0450-0","article-title":"Follicular and papillary carcinoma: a thyroid collision tumor","volume":"65","author":"Plauche","year":"2013","journal-title":"Indian J Otolaryngol Head Neck Surg"},{"key":"2026090305051104000_19.5.e267185.4","doi-asserted-by":"publisher","DOI":"10.1002\/hed.20024"},{"key":"2026090305051104000_19.5.e267185.5","doi-asserted-by":"crossref","first-page":"1137","DOI":"10.1007\/s12105-021-01323-7","article-title":"Papillary and Medullary Thyroid Carcinomas Presenting as Collision Tumors: A Case Series of 21 Cases at a Tertiary Care Cancer Center","volume":"15","author":"Thomas","year":"2021","journal-title":"Head Neck Pathol"},{"key":"2026090305051104000_19.5.e267185.6","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1111\/j.0954-6820.1981.tb11620.x","article-title":"Concurrent medullary and papillary thyroid carcinoma in the same thyroid lobe and in siblings","volume":"209","author":"Lamberg","year":"1981","journal-title":"Acta Med Scand"},{"key":"2026090305051104000_19.5.e267185.7","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1677\/erc.1.00901","article-title":"Medullary and papillary carcinoma of the thyroid gland occurring as a collision tumour: report of three cases with molecular analysis and review of the literature","volume":"12","author":"Rossi","year":"2005","journal-title":"Endocr Relat Cancer"},{"key":"2026090305051104000_19.5.e267185.8","doi-asserted-by":"publisher","DOI":"10.1200\/JCO.2016.67.7419"},{"key":"2026090305051104000_19.5.e267185.9","doi-asserted-by":"publisher","DOI":"10.1002\/hed.23936"},{"key":"2026090305051104000_19.5.e267185.10","doi-asserted-by":"crossref","first-page":"60","DOI":"10.4103\/trp.trp_6_18","article-title":"Collision tumors of the thyroid: Review of literature and report of a case of papillary\u2013Follicular collision tumor","volume":"15","author":"Thomas","year":"2018","journal-title":"Thyroid Res Pract"},{"key":"2026090305051104000_19.5.e267185.11","unstructured":"DeVita VT , Lawrence TS , Rosenberg SA . DeVita, Hellman, and Rosenberg\u2019s cancer: principles and practice of oncology. 12th edn. n.d:1363."},{"key":"2026090305051104000_19.5.e267185.12","doi-asserted-by":"crossref","first-page":"841","DOI":"10.1177\/10507256251363120","article-title":"2025 American Thyroid Association Management Guidelines for Adult Patients with Differentiated Thyroid Cancer [Erratum in: Thyroid. 2025 Nov;35(11):1350]","volume":"35","author":"Ringel","year":"2025","journal-title":"Thyroid\u00ae"},{"key":"2026090305051104000_19.5.e267185.13","doi-asserted-by":"crossref","first-page":"598","DOI":"10.4103\/0377-4929.142684","article-title":"Mixed medullary-papillary carcinoma of the thyroid: report of two cases and review of the literature","volume":"57","author":"Gurkan","year":"2014","journal-title":"Indian J Pathol Microbiol"},{"key":"2026090305051104000_19.5.e267185.14","article-title":"Coexistence of Two Different Thyroid Malignancies: A Collision Phenomenon","volume":"12","author":"Pishdad","year":"2020","journal-title":"Cureus"},{"key":"2026090305051104000_19.5.e267185.15","doi-asserted-by":"crossref","first-page":"S150","DOI":"10.1017\/S0022215116000578","article-title":"Management of thyroid cancer: United Kingdom National Multidisciplinary Guidelines","volume":"130","author":"Mitchell","year":"2016","journal-title":"J Laryngol Otol"},{"key":"2026090305051104000_19.5.e267185.16","doi-asserted-by":"crossref","first-page":"703","DOI":"10.4158\/EP12430.RA","article-title":"Medullary thyroid carcinoma","volume":"19","author":"Griebeler","year":"2013","journal-title":"Endocr Pract"},{"key":"2026090305051104000_19.5.e267185.17","doi-asserted-by":"crossref","first-page":"E125","DOI":"10.1002\/dc.24615","article-title":"Cytologic features of a case of mixed medullary and follicular cell-derived thyroid carcinoma with review of the literature","volume":"49","author":"Chambers","year":"2021","journal-title":"Diagn Cytopathol"},{"key":"2026090305051104000_19.5.e267185.18","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-319-22542-5_9"},{"key":"2026090305051104000_19.5.e267185.19","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2019-00177"},{"key":"2026090305051104000_19.5.e267185.20","doi-asserted-by":"crossref","DOI":"10.3390\/jcm9072316","article-title":"The Impact of the Extent of Surgery on the Long-Term Outcomes of Patients with Low-Risk Differentiated Non-Medullary Thyroid Cancer: A Systematic Meta-Analysis","volume":"9","author":"Bojoga","year":"2020","journal-title":"J Clin Med"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr-2025-267185","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T12:05:18Z","timestamp":1788437118000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr-2025-267185"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5]]},"references-count":20,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2026,5,27]]},"published-print":{"date-parts":[[2026,5]]}},"alternative-id":["10.1136\/bcr-2025-267185"],"URL":"https:\/\/doi.org\/10.1136\/bcr-2025-267185","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5]]}}}