Pattern of thyroid lesions and role of fine needle aspiration cytology (FNA) in the management of thyroid enlargement: a retrospective study from a teaching hospital in Riyadh

The study aims to determine the cytological pattern of thyroid lesions, in addition to the utility and accuracy of fine needle aspiration (FNA) cytolo gy as an initial diagnostic method in the investigation of these lesions am ong Saudi patients. Four hundred and seventy-nine (479) FNAs were performed on patients presenting with diffuse or nodular thyroid enlargement to the endocrinology clinic at King Khalid University Hospital in Riyadh during th e period September 1993 to September 1996. The results of the FNA and the 1 25 histological diagnoses obtained from the subsequent partial and subtotal thyroidectomies were retrospectively and independently reviewed and compar ed by two cytopathologists. The results of the FNA cytological diagnosis sh owed that 372 patients (77.7%) had benign lesions, 24 (5%) had lesions whic h were suspected of malignancy, 25 (5.2%) had malignant neoplasms, and 58 ( 12.1%) had FNAs which were inadequate for cytological assessment. Colloid a nd adenomatous nodules were the most common benign lesions reported (47.8%) . Papillary carcinoma was the most common malignant neoplasm (4.2%). Despit e the relatively limited number of patients who underwent surgery, cytohist opathology combined with statistical analysis of the results showed that ou r FNA accuracy rate is in the region of 94.4% with a sensitivity of 78% and a specificity of 100%. In addition, the negative predictive value (NPV) an d the positive predictive value (PPV) of FNA thyroid cytology were 93% and 100% respectively. Our findings indicate that FNA cytology can be used effe ctively in the evaluation of both nodular and diffuse thyroid lesions whils t cytopathologist should be aware of the potential diagnostic pitfalls and the limitations of the procedure in the diagnosis of follicular, cystic, an d small neoplasms, the positive identification of thyroiditis and most case s of neoplasia by itself provides justification for FNA.