Background- Fine Needle Aspiration Cytology (FNAC) is widely considered as diagnostic study of choice in assessment of thyroid lesions.

Aim- The aim of this study is to determine the various cytological patterns found in all Solitary thyroid nodules (STNs).

Setting and Design- The present study is a five retrospective study of FNAC of thyroid STNs performed in pathology department of our institute during the period of January 2009 to December 2013.

Material and Methods- The records of 185 patients who had undergone FNAC during the study period were retrieved and information about age, sex and cytological diagnosis were extracted and the corresponding original slides were reviewed. Cytological diagnosis were categorized as Neoplastic (benign/malignant), Non-neoplastic (nodular colloid goiter, colloid cyst, thyroiditis) and third category as suspicious (follicular neoplasm).

Results:- A total of 185 FNACs of STNs were done during the study period. The results of cytological diagnosis showed that 11 cases (5.94%) had neoplastic cytological pictures (benign/malignant), 140 cases (73.37%) had non-neoplastic pictures of STN. The cytological picture also showed 37 cases (19.69%) were suspicious cytomorphology.

Conclusion- FNAC is a sensitive, specific and accurate initial diagnostic test for preoperative evaluation of STN and can be easily performed as an OPD procedure.

Keywords: Fine needle aspiration cytology, solitary thyroid nodule.