{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T01:26:44Z","timestamp":1783906004870,"version":"3.55.0"},"reference-count":9,"publisher":"The Endocrine Society","issue":"8","license":[{"start":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T00:00:00Z","timestamp":1783900800000},"content-version":"vor","delay-in-days":11,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,7,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Calcitonin-secreting neuroendocrine neoplasms of the lung are extremely rare. Differentiating medullary thyroid carcinoma (MTC) from ectopic calcitonin secretion is challenging. Elevated calcitonin usually triggers a thyroid-focused workup, but ectopic secretion must be considered to avoid misdiagnosis and unnecessary thyroidectomy. We report a 54-year-old man presenting with weight loss and back pain. Serum calcitonin was markedly elevated at 1011\u2005pg\/mL (SI: 293\u2005pmol\/L) (reference range, &amp;lt;16\u2005pg\/mL [SI: &amp;lt;4.67\u2005pmol\/L] for basal levels in men). Thyroid ultrasonography showed a &amp;gt;2\u2005cm nodule in the right thyroid lobe. Fine-needle aspiration cytology revealed atypia of undetermined significance, and calcitonin washout was negative. 18F-fluorodeoxyglucose positron emission tomography showed intense uptake in a 4.5\u2005cm right lower lobe pulmonary mass and a 6.5\u2005cm right adrenal mass, with no thyroid uptake. Histopathological analysis of the lung lesion confirmed high-grade pulmonary neuroendocrine carcinoma. Systemic chemotherapy was initiated, but the patient demonstrated disease progression and died from respiratory failure. This case illustrates how ectopic calcitonin production can mimic MTC. Comprehensive evaluation with functional imaging and immunohistochemistry is essential for accurate diagnosis. Multidisciplinary collaboration is crucial in distinguishing thyroid malignancy from ectopic hypercalcitoninemia.<\/jats:p>","DOI":"10.1210\/jcemcr\/luag194","type":"journal-article","created":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T01:03:05Z","timestamp":1783904585000},"source":"Crossref","is-referenced-by-count":0,"title":["Ectopic calcitonin-secreting pulmonary neuroendocrine tumor mimicking medullary thyroid carcinoma"],"prefix":"10.1210","volume":"4","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6601-7791","authenticated-orcid":false,"given":"Riza G\u00f6khan","family":"Baykal","sequence":"first","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7729-5586","authenticated-orcid":false,"given":"Sefika Burcak","family":"Polat","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Y\u0131ld\u0131r\u0131m Beyaz\u0131t University Faculty of Medicine, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3895-5817","authenticated-orcid":false,"given":"Ekin Yigit","family":"K\u00f6roglu","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2501-935X","authenticated-orcid":false,"given":"Oya","family":"Topaloglu","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Y\u0131ld\u0131r\u0131m Beyaz\u0131t University Faculty of Medicine, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7437-1176","authenticated-orcid":false,"given":"Reyhan","family":"Ersoy","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Y\u0131ld\u0131r\u0131m Beyaz\u0131t University Faculty of Medicine, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7526-8827","authenticated-orcid":false,"given":"Bekir","family":"Cakir","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Ankara Y\u0131ld\u0131r\u0131m Beyaz\u0131t University Faculty of Medicine, Ankara Bilkent City Hospital , Ankara 06800 ,","place":["T\u00fcrkiye"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"80","published-online":{"date-parts":[[2026,7,13]]},"reference":[{"issue":"6","key":"2026071221005306400_luag194-B1","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1089\/thy.2014.0335","article-title":"Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma","volume":"25","author":"Wells","year":"2015","journal-title":"Thyroid"},{"issue":"1","key":"2026071221005306400_luag194-B2","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1007\/s12020-023-03485-6","article-title":"Appropriate and mindful measurement of serum calcitonin in patients with thyroid nodules. A white paper","volume":"83","author":"Trimboli","year":"2024","journal-title":"Endocrine"},{"issue":"2","key":"2026071221005306400_luag194-B3","doi-asserted-by":"crossref","first-page":"450","DOI":"10.1210\/jc.2006-1590","article-title":"Predictive value of serum calcitonin levels for preoperative diagnosis of medullary thyroid carcinoma in a cohort of 5817 consecutive patients with thyroid nodules","volume":"92","author":"Costante","year":"2007","journal-title":"J Clin Endocrinol Metab"},{"issue":"6","key":"2026071221005306400_luag194-B4","doi-asserted-by":"crossref","first-page":"565","DOI":"10.1089\/thy.2008.0403","article-title":"Medullary thyroid cancer: management guidelines of the American thyroid association","volume":"19","author":"American Thyroid Association Guidelines Task Force","year":"2009","journal-title":"Thyroid"},{"issue":"4","key":"2026071221005306400_luag194-B5","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1530\/EC-21-0071","article-title":"Calcitonin-secreting neuroendocrine neoplasms of the lung: a systematic review and narrative synthesis","volume":"10","author":"Llewellyn","year":"2021","journal-title":"Endocr Connect"},{"issue":"10","key":"2026071221005306400_luag194-B6","doi-asserted-by":"crossref","first-page":"1507","DOI":"10.1515\/cclm-2015-0058","article-title":"Serum calcitonin negative medullary thyroid carcinoma: a systematic review of the literature","volume":"53","author":"Trimboli","year":"2015","journal-title":"Clin Chem Lab Med"},{"issue":"6274","key":"2026071221005306400_luag194-B7","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1126\/science.aad7969","article-title":"Pulmonary neuroendocrine cells function as airway sensors to control lung immune response","volume":"351","author":"Branchfield","year":"2016","journal-title":"Science"},{"issue":"5","key":"2026071221005306400_luag194-B8","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1016\/j.molonc.2010.05.002","article-title":"Cell of origin of lung cancer","volume":"4","author":"Sutherland","year":"2010","journal-title":"Mol Oncol"},{"issue":"1","key":"2026071221005306400_luag194-B9","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1164\/ajrccm.149.1.8111580","article-title":"Calcitonin elevation in small cell lung cancer without ectopic production","volume":"149","author":"Kelley","year":"1994","journal-title":"Am J Respir Crit Care Med"}],"container-title":["JCEM Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/academic.oup.com\/jcemcr\/article-pdf\/4\/8\/luag194\/68762035\/luag194.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/jcemcr\/article-pdf\/4\/8\/luag194\/68762035\/luag194.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T01:03:07Z","timestamp":1783904587000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/jcemcr\/article\/doi\/10.1210\/jcemcr\/luag194\/8732981"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,2]]},"references-count":9,"journal-issue":{"issue":"8","published-print":{"date-parts":[[2026,7,2]]}},"URL":"https:\/\/doi.org\/10.1210\/jcemcr\/luag194","relation":{},"ISSN":["2755-1520"],"issn-type":[{"value":"2755-1520","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2026,8]]},"published":{"date-parts":[[2026,7,2]]},"article-number":"luag194"}}