Clinical data: A 63-year-old woman was referred for evaluation of a suspected hyperparathyroidism. She suffered multiple fractures and recurrent nephrolithiasis. The first fracture occurred 2 years ago.

Palpation: Both lobes were nodular.

Laboratory tests: TSH 0.98 mIU/L, calcium 2.71 mM/L, phosphorus 0.74 mM/L, parathormone 133.0 pg/mL.

Ultrasonography: The thyroid was echonormal and contained multiple inhomogeneous, hyperechogenic nodules. There was a hypoechogenic lesion in the dorsal part or dorsal to the lower pole of the right lobe.

Aspiration cytology resulted in benign lesion which might correspond to parathyroid adenoma.

Wash-out thyroglobulin exceeded 476 mg/L wash-out parathormone exceeded 175 pg/mL.

Scintigraphy disclosed parathyroid lesion corresponding to the mass in the lower-dorsal part of the thyroid.

Total thyroidectomy was performed with the removal of the right lower parathyroid. Histopathology: benign, hyperplastic nodules in both lobes and a parathyroid adenoma corresponding to the right lower parathyroid.

Comment. The wash-out technique is very useful in a ventral lesion. This parathyroid adenoma was located dorsal to thyroid parenchyma, therefore the wash-out contained thyroidal elements, as well. In this patient this caused no problem because we have marker of a parathyroid tissue. Nevertheless, this case illustrates the limitations of the wash-out technique in the event of a secondary tumor covered ventral with thyroid parenchyma.