Clinical presentation: A 49-yr-old woman came to a follow-up examination. A cystic nodule has been diagnosed for 5 years when the size of the nodule was 28x25x38 mm (width, depth and length, respectively). At the first occasion 6 mL brown fluid was aspirated and cytology resulted in benign cystic-colloid goiter. The patient had no complaints and the cystic nodule has not refilled.

Palpation: The right lobe was suspicious having a nodule.

Laboratory test: TSH 1.06 mIU/L.

Ultrasonography. The thyroid was echonormal. There was a hypoechoic nodule in the ventro-lateral part of the lobe. The dorsal surface of the nodule reached the dorsal part of the lobe and was adjacent to the muscle fiber. The nodule and the muscle fiber have identical echogenicity.

Cytology resulted in benign colloid goiter.

Comment.

1. This is an example of non-pathological blur. If a lesion has identical echogenicity to the adjacent tissue which is either the thyroid parenchyma or the extrathyroidal tissue, then this results in indistinctive borders.
   
2. It is equivocal whether the dorsal contour of the nodule is abutting or not. The capsule is discontinuous at some parts where the nodule is in contact with the dorsal surface of the lobe.