Clinical presentation: A 40-year-old woman was referred for an evaluation of a nodular goiter which was discovered by the patient herself.

Palpation: a moderately firm nodule in the left lobe.

Functional state: euthyroidism (TSH-level 2.18 mIU/L).

Ultrasonography: The thyroid was echonormal. There was a seemingly simple cyst in the right and an echonormal nodule in the left lobe. After the evacuation of the cyst, a moderately hypoechogenic solid part remained which presented microcalcifications.

Cytology of the lesion in the right lobe resulted in suspicion of papillary cancer.

Histopathology disclosed a papillary microcancer cancer in the right lobe with 4 mm maximal diameter and a normofollicular adenoma in the left thyroid.

Comment. The lesson of this case is that a seemingly pure cystic nodule can be malignant. It is obvious that the risk of malignancy in a truly pure cyst is zero. The issue is the correct interpretation of the lesion. We cannot group this lesion into the peripheral or central-type subgroup, but after the aspiration it became evident that this is not a pure cyst.