Nuclear grooves. Valuable diagnostic feature in May-Grünwald-Giemsa-stained fine needle aspirates of papillary carcinoma of the thyroid.

Recent reports have indicated the usefulness of nuclear grooves (clefts or notches) as an additional criterion for the diagnosis of papillary thyroid carcinoma in fine needle aspirates; most of these studies were carried out on alcohol-fixed material stained with the Papanicolaou stain or with hematoxylin and eosin, which yield good nuclear details. In the present study air-dried thyroid aspirates stained with the widely used May-Grünwald-Giemsa stain were evaluated. Nuclear grooves were observed in 88% of the May-Grünwald-Giemsa-stained aspirates from papillary thyroid carcinoma, usually in substantial numbers. A few grooved nuclei were seen in a small percentage of the other thyroid aspirates studied. These results show that nuclear grooves can also be used as a possible marker of papillary carcinoma of the thyroid in May-Grünwald-Giemsa-stained aspirates.