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-Grunwald-Giemsa stain were evaluated. Nuclear grooves were observed in 88% of the May-Grunwald-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-Grunwald-Giemsa-stained aspirates.