An analysis of 5194 fine needle aspiration biopsy samples

To evaluate the usefulness of fine needle aspiration biopsy (FNAB) as an initial investigation in the diagnosis of mass lesions and to determine the accuracy of the test in a Sri Lankan setting.

5149 FNAB samples were retrospectively analysed. The lesions were categorised according to the site and as benign, malignant or atypical/suspicious. Initial cytological diagnosis was compared with the histological diagnosis. Overall accuracy rate, and false positive and negative rates for thyroid, breast and lymphnode aspirates were determined.

Department of Pathology, Faculty of Medicine Colombo and Asiri Hospital, Colombo.

There were 3577 thyroids, 1271 breast lumps, 167 lymph nodes, 58 extra-thyroidal head and neck, 61 deep visceral, and 60 miscellaneous lesions. 3596 (69.2%) were benign and 592 (11.3%) malignant. Histological follow up was available for 1092 (24%). The overall accuracy rate for benign and malignant lesions was 94%. False positive and negative rates for thyroid malignancies were 1.6% and 5.1% respectively. There were no false positives for breast malignancies, and the false negative rate was 6.2%. There were no false positives for lymphoid malignancies.

This cost-effective, minimally invasive technique can be applied to assess any accessible lesion with existing facilities in Sri Lanka. The accuracy and false negative and positive rates in this series are similar to those of recognised centres overseas.