{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,6]],"date-time":"2026-06-06T15:20:41Z","timestamp":1780759241552,"version":"3.54.1"},"reference-count":15,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,12,5]],"date-time":"2024-12-05T00:00:00Z","timestamp":1733356800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Malignant hypercalcemia is usually caused by osteolytic processes of metastases, production of parathormone-related peptide, or secretion of 1,25-dihydroxyvitamin D. Ectopic PTH (parathyroid hormone) production by malignancy is very unusual.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Case report and review of the literature.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>We present a case of a malignant hypercalcemia with a presentation that mimicked primary hyperparathyroidism in a patient with endometrial carcinoma. Finally, ectopic production of PTH by a rapidly progressive neuroendocrine tumor was proven. Systematic literature review revealed ectopic PTH production by malignancies as an extremely rare cause of hypercalcemia and that most cases were initially misdiagnosed as primary hyperparathyroidism and underwent unnecessary surgical neck exploration in almost all cases.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>In patients even with a suggestive constellation of primary hyperparathyroidism, an ectopic paraneoplastic PTH source should be considered if the localization diagnostics are without abnormalities or if the PTH values are unusually high. Concomitant elevated LDH levels should also raise concern about an ectopic malignant source.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fonc.2024.1422131","type":"journal-article","created":{"date-parts":[[2024,12,5]],"date-time":"2024-12-05T06:29:01Z","timestamp":1733380141000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":5,"title":["Case report: Ectopic production of intact parathyroid hormone (iPTH) by malignoma mimicking primary hyperparathyroidism"],"prefix":"10.3389","volume":"14","author":[{"given":"Ralph","family":"Wendt","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marie","family":"Heller","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel","family":"H\u00e4rtwig","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sven Oliver","family":"Ullmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Heike","family":"Bisanz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniela","family":"Geister","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luisa","family":"Mantovani","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ulrike","family":"Hoffmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2024,12,5]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1056\/nejmcp2113128","article-title":"Cancer-associated hypercalcemia","volume":"386","author":"Guise","year":"2022","journal-title":"N Engl J Med"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1002\/jso.2930370104","article-title":"Malignancy and concomitant primary hyperparathyroidism","volume":"37","author":"Strodel","year":"1988","journal-title":"J Surg Oncol"},{"key":"B3","doi-asserted-by":"publisher","first-page":"28","DOI":"10.1136\/pgmj.71.831.28","article-title":"Survival in hypercalcaemic patients with cancer and co-existing primary hyperparathyroidism","volume":"71","author":"Hutchesson","year":"1995","journal-title":"Postgrad Me\u0301d J"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1093\/bjsopen\/zrac118","article-title":"The value of intraoperative parathyroid hormone monitoring in patients with primary hyperparathyroidism and varying baseline parathyroid hormone levels","volume":"6","author":"Hargitai","year":"2022","journal-title":"BJS Open"},{"key":"B5","doi-asserted-by":"crossref","DOI":"10.1210\/jcem-68-5-976","article-title":"Ectopic production of parathyroid hormone by small cell lung cancer in a patient with hypercalcemia","volume":"68","author":"Yoshimoto","year":"1989","journal-title":"J Clin Endocrinol Metab."},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.1385\/endo:27:1:083","article-title":"Parathyroid hormone expression in a patient with metastatic nasopharyngeal rhabdomyosarcoma and hypercalcemia","volume":"27","author":"Wong","year":"2005","journal-title":"Endocrine"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1210\/jc.2005-2095","article-title":"Hypercalcemia of Malignancy due to ectopic transactivation of the parathyroid hormone gene","volume":"91","author":"VanHouten","year":"2006","journal-title":"J Clin Endocrinol Metab"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.76.5.7684395","article-title":"Production of parathyroid hormone by a Malignant nonparathyroid tumor in a hypercalcemic patient","volume":"76","author":"Strewler","year":"1993","journal-title":"J Clin Endocrinol Metab"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.79.3.8077382","article-title":"A thymoma as a cause of true ectopic hyperparathyroidism","volume":"79","author":"Rizzoli","year":"1994","journal-title":"J Clin Endocrinol Metab"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1056\/nejm199011083231907","article-title":"Hypercalcemia and ectopic secretion of parathyroid hormone by an ovarian carcinoma with rearrangement of the gene for parathyroid hormone","volume":"323","author":"Nussbaum","year":"1990","journal-title":"N Engl J Med"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.81.10.8855839","article-title":"Ectopic production of intact parathyroid hormone by a squamous cell lung carcinoma","volume":"81","author":"Nielsen","year":"1996","journal-title":"Vivo vitro. 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