COMPARISON OF THE FOUR-CATEGORY VS FIVE-CATEGORY THYROID FINE NEEDLE ASPIRATION BIOPSY CLASSIFICATIONS

Abstract

Objectives: Comparison of the two different classification systems of fine needle aspiration biopsy (FNAB).

Evaluation: The evaluation of FNAB results is generally based on a widely accepted classification with four categories: insufficient material, benign, suspicious and malignant lesions. However, occasionally, some aspiration biopsy materials may not correspond to one of these four groups. This may cause difficulty in management of these cases. Recently a new intermediate category is added to alleviate this problem, which formed a new five-category classification system.

Method: 236 FNAB and thyroidectomy specimens that were collected during period of 1996 and 2002 at Kocaeli University, Department of General Surgery were evaluated retrospectively. Statistical analyses were done with Chi-square and Fisher's exact tests utilizing InStat software package.

Results: Cytopathological samples were grouped as insufficient materials (48), benign (120), suspicious (61) and malignant (7) lesions. Surgical specimens of these samples showed malignant histopathology in 8.3%, 3.3%, 18% and 100%, respectively. Findings were statistically significant in the third group. When five-category system is used to classify the same samples, groups formed as follows: insufficient material (48), benign (120), indeterminate (34), suspicious (27) and malignant (7) lesions. The malignant histopathology was found to be 8.3%, 3.3%, 8.8%, 29.6% and 100%, respectively, resulting in a significant difference in the fourth category.

Conclusion: Five-category system in evaluating the FNAB results compared with the four-category may be more definitive in determining the frequency of malignancy.