Clinical data: a 41-year-old woman was referred for an evaluation of a thyroid nodule detected on physical examination. She was investigated because of fatigue and hypertension.

Palpation: an elastic nodule in the left lobe.

Laboratory tests: TSH 0.81 mIU/L, anti-TPO 0.1 U/mL.

Ultrasound. The thyroid was echonormal. The right lobe presented several small hypoechogenic and cystic lesion. There was a large mixed nodule occupying almost the entire left lobe. The solid part of the lesion was echonormal and contained hyperechogenic granules and patches. The lesion presented a type 1 vascular pattern. Only a small part of the nodule was surrounded with halo.

Two US-guided aspirations were performed. A minimal amount of brown fluid was gained. Preliminary cytological diagnosis: tumor with great probability an oxyphilic tumor.

Wash-out thyroglobulin level exceeded 478 microgram/L, serum calcitonin was calcitonin 0.84 pM/L (normal value: 0-3.36).

Final cytological diagnosis: oxyphilic tumor.

Left lobectomy was performed. Histopathology disclosed an oxyphilic adenoma

Comments.

1. The nodule is surrounded with halo but lacks perinodular blood flow. The latter is explained by the compression of the cystic fluid.

2. The solid part is very unusual. The presence of hyperechogenic patches raises the suspicion of a medullary carcinoma.