Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) may rarely coexist with non-medullary thyroid carcinoma (NMTC). We report the clinical manifestation and management of nine cases of synchronous PH and NMTC.

Cases: Eight women and one man were included (mean age at diagnosis: 64±6.6 years). In all cases, PH was the initial diagnosis, whereas NMTC was detected incidentally, after ultrasound assessment for PH. The histological diagnosis of NMTC was classical papillary thyroid carcinoma (PTC) in all cases, with follicular subtype in four cases. In one patient, medullary carcinoma was also detected and a diagnosis of multiple-endocrine neoplasia type 2B syndrome was set. In three cases (33.3%), NMTC was multifocal. Extrathyroidal extension was detected in one case, but without metastatic disease. In seven cases (78%), maximum NMTC diameter was <10 mm (mean diameter: 7.6±4.4 mm). Thyroid autoimmunity was positive in two cases.

The histological diagnosis of PHPT was single parathyroid adenoma (mean diameter: 15.4±19.3 mm, in six cases on the right side) in all cases. In one case, the adenoma was intrathyroidal. Nephrolithiasis was diagnosed in one case, hypercalciuria in two, whereas low bone mass in eight patients. Preoperative mean parathyroid hormone (PTH) and total calcium concentrations were 133.5±43.9 and 11.3±0.8 mg/dl (corrected calcium: 11±0.78 mg/dl), respectively. Cardiovascular risk factors, such as arterial hypertension, dyslipidemia and/or hyperglycemia were diagnosed in six cases (66.7%).

PH and NMTC were successfully managed with parathyroidectomy and total thyroidectomy (mean post-operative PTH concentrations: 33.3±24.7 pg/ml). No case developed post-operative hypocalcemia. Prophylactic central lymph node resection was performed in one patient. No recurrence of either PH or NMTC has been reported (mean follow-up time: 3.8±5.1 years).

Conclusions: NMTC may rarely be incidentally detected in patients with PH. It is usually unifocal microcarcinoma of classical PTC subtype, without extrathyroidal extension. The pathogenetic mechanisms linking these two endocrine entities are currently unknown.