Coincidence of primary hyperparathyroidism and nonmedullary thyroid carcinoma.

The incidence of primary hyperparathyroidism (pHPT) combined with nonmedullary thyroid carcinoma (NMTC) has been reported between 2-13%. To date, it remains controversial whether these 2 pathologies occur coincidental or are caused by specific risk factors or genetic changes. The aim of this study was to evaluate the clinical and histological characteristics of NMTC associated with pHPT. We reviewed prospective database records of 1 464 unselected, consecutive patients who were treated for pHPT in our institution between 1986 and 2012 and identified 41 NMTC (2.8%). The collective consisted of 35 papillary (PTC) and 6 follicular (FTC) thyroid carcinomas. Our collective of 41 NMTC including 34 single adenomas and 7 multiglandular diseases consisted of 33 females and 8 males. Patients with FTC demonstrated significant lower preoperative PTH levels compared to PTC. Interestingly, NMTC were predominantly located on the right side. FTC had significant larger tumors as well as demonstrated increased extrathyroidal growth and lymph node metastases. In 71% pHPT and NMTC were diagnosed synchronously. The comorbidity of pHPT and NMTC occurs in about 3%. As pHPT is often operated by a focal minimally invasive approach, we advocate a mandatory preoperative thyroid ultrasound for all patients with pHPT to be able to identify synchronous thyroid disease.