Detection and diagnosis of parathyroid incidentalomas during thyroid sonography

Purpose. The aim of our study was to evaluate the incidence of incidentally found parathyroid adenomas (incidentalomas) in patients undergoing sonogra phy of the neck for thyroid disease. Methods. A total of 1,686 patients (305 men and 1,381 women) underwent sono graphy of the neck; the mean age was 49.6 +/- 21.7 years. In 38 patients (2 .3%; 7 men and 31 women) with a mean age of 48.7 +/- 14.7 years, hypoechoic , homogeneous, oval nodules (mean volume, 1.0 +/- 0.9 cm(3)) adjacent to th e thyroid parenchyma were observed. All these lesions, compatible with the shape of an enlarged parathyroid gland, underwent ultrasound-guided fine-ne edle aspiration biopsy (FNAB), with measurement of parathyroid hormone (PTH ) and thyroglobulin (Tg) levels in the needle washings (FNAB-PTH and FNAB-T g). Biochemical screening for hyperparathyroidism was also performed. Results. Cytologic examination plus FNAB-PTH/FNAB-Tg measurements revealed the presence of cellular material consistent with parathyroid tissue in 9 p atients (24%), thyroid tissue in 22 patients (58%), and lymphoid tissue in 4 patients (11%). A tissue diagnosis was not established in 3 patients (8%) . Five of 9 patients with parathyroid enlargement had high serum PTH and ca lcium levels. Conclusions. Enlarged parathyroid glands may be incidentally discovered dur ing sonography of the thyroid. in patients with thyroid disease, the positi ve-predictive value of sonography in the identification of parathyroid tiss ue was tow. Ultrasound-guided FNAB-PTH determination should be carried out when parathyroid adenoma is suspected. The incidental finding of an enlarge d parathyroid may or may not be associated with yet undiagnosed hyperparath yroidism. (C) 1999 John Wiley & Sons, Inc.