The diagnostic value of parathyroid assay in wash-out fluid from fine needle aspiration biopsy of neck masses in primary hyperparathyroid patients with uncertain 99mTC-SESTAMIBI scintigraphy.

PURPOSE: To evaluate the value of parathyroid hormone assay in fine needle aspiration biopsy wash out fluid (PTH-FNAB) in the localization of parathyroid neoplasia (PN) in primary hyperparathyroid (pHPT) patients displaying multinodular goiter (MNG) or Hashimoto’s thyroiditis (HT) and uncertain 99mTc-sestaMIBI scintigraphy (MIBI). SUBJECTS AND METHODS: Forty-two neck lesions from 24 patients with uncertain MIBI (group I) were compared to a similar group of 16 cases with a defined MIBI localization of PN (group II). In all cases neck ultrasound (US), MIBI, cytology and PTH-FNAB were performed. PTH-FNAB was considered indicative for PN when its concentration exceeded 3 times the maximal level (34.3 pg/ml) found in not-PN lesions. RESULTS: Group I was subdivided in four subgroups (A-B-C-D) on the basis of MIBI negative pattern (A) or several degrees of mismatch between MIBI and US (B-D). All PTH-FNAB positive (366->2500 pg/ml) lesions resulted PN at histology (38 adenomas, 2 hyperplasic parathyroid, and 1 carcinoma), resulting in 100% of sensivity and specificity. In particular, PTH-FNAB correctly identified all PN in group I and II, while MIBI clearly identified PN only in group II. MIBI and cytology showed a low diagnostic accuracy reaching a sensitivity of 70 % with a specificity of 25 % and a sensitivity of 53.7% with a specificity of 100 % respectively. CONCLUSIONS: PTH-FNAB provides evidence to be an accurate and safe tool to precisely localize PN in pHPT patients with MNG or HT and uncertain MIBI although does not contribute in cases with concordant studies.