Abstract
The gold standard to determine the cause of primary hyperparathyroidism (PHPT) is bilateral neck exploration. As most cases are caused by parathyroid adenoma, there is a movement toward preoperative localization of the abnormal gland by ultrasound and/or Tc^99^‐sestamibi scan and minimally invasive parathyroidectomy. Nonpalpable thyroid nodules are common and cannot be differentiated from parathyroid lesions by imaging alone. This study examines cytopathologist‐performed ultrasound‐guided fine‐needle aspiration (UG‐FNA) in diagnosis of parathyroid lesions. Between January 1, 2007 and December 31, 2008, seven patients with PHPT or other parathyroid lesions with one or more sonographically‐visible thyroid masses underwent cytopathologist‐performed UG‐FNA with immediate cytological evaluation (ICE). One mass was palpable and nine were nonpalpable. Three parathyroid adenomas, two benign colloid nodules, one papillary carcinoma, three parathyroid cysts, and one thyroid cyst were diagnosed. The nodules in three patients with parathyroid adenomas were identified as follicular lesion/neoplasm on ICE. Additional UG‐FNA passes were made to obtain tissue for immunohistochemistry stains, which confirmed parathyroid origin. Two of these patients had a separate benign colloid nodule and one had a thyroid cyst diagnosed by UG‐FNA. The PHPT patient with papillary carcinoma on UG‐FNA had the malignancy confirmed at surgery and a sonographically occult parathyroid adenoma. The three patients with thyroid cysts identified by radiology were suspected of being parathyroid cysts on the basis of real‐time sonographic features at the biopsy table. The clear cyst fluid obtained by UG‐FNA had markedly elevated PTH. Cytopathologist‐performed UG‐FNA can distinguish between parathyroid and thyroid nodules in patients with suspected parathyroid lesions. Diagn. Cytopathol. 2010. © 2009 Wiley‐Liss, Inc.