Role of nuclear grooves in the cytological diagnosis of papillary carcinoma thyroid

Abstract

Introduction: It is well known that nuclear grooves play a major role in the diagnosis of papillary carcinoma thyroid (PCT). Furthermore, grooves are found in many nonneoplastic lesions of thyroid. Aims: The aim of this study is to calculate the percentage of nuclear grooves in histopathologically proven cases of papillary carcinoma and nonneoplastic lesions (Hashimoto's thyroiditis and colloid goiter). Materials and Methods: This retrospective study was carried out by reviewing the data and cytology smears of 21 histopathologically confirmed cases of PCT and 10 cases each of Hashimoto's thyroiditis and colloid goiter. The percentage of nuclear grooves was calculated in oil immersion by counting 100–500 cells depending on the cellularity. Results: The percentage of nuclear grooving ranged from 15% to 85% in the papillary carcinoma cases. Greater than 20% nuclear grooves were observed in 19 (90.4%) of the cases. Nuclear crowding and overlapping, pale chromatin, nuclear grooves, nuclear enlargement, and prominent nucleoli were seen in all (100%) cases. Intranuclear cytoplasmic pseudoinclusions were seen in only 5 (23.8%) of the cases. Histiocytes, metaplastic cells, and multinucleated giant cells were seen in 12 (57.1%), 10 (47.6%), and 6 (28.5%) of the cases. The percentage of nuclear grooves in nonneoplastic cases overall observed was Conclusion: Whenever in doubt, a diagnosis of papillary carcinoma can be offered confidently by this semiquantitative approach for grooves in combination with other features.