Role of fine needle aspiration cytology in the diagnosis of goiter.

Abstract

Enlargement of the thyroid gland is a common occurrence in most parts of the world especially in the iodine-deficient goiter belt areas. Vast majority of these lesions are benign but they invariably lead to a series of investigations among which FNAC plays a pivotal role. Although many studies have reported diagnostic accuracy of FNAC in detecting neoplasms, there have been few studies where the role of FNAC in the diagnosis of goiter along with their diagnostic pitfalls has been evaluated. The present study was undertaken to assess the accuracy of FNAC in diagnosis of goiter and to highlight its limitations and diagnostic pitfalls. 771 cases over a five-year period were retrieved from the files of Cytopathology Laboratory, Department of Pathology at the All India Institute of Medical Sciences, New Delhi. They included 733 cases where the cytological diagnosis was goiter or suggestive of goiter along with 38 cases in which the histological diagnosis was goiter while the cytological diagnosis was cystic change or neoplasm. FNAC with minimum of two passes were performed in each case and May Grünwald Giemsa and Papanicolaou stains were done. Histology was available in 192 cases. The cytological and histological concordance was determined and the FNAC smears and histological sections in cases showing discordance were reviewed. There was cytological and histological concordance 130/168 (77.38%) cases. In 34 cases (20.23%) no diagnosis could be offered because of cystic change. A false positive cytologic diagnosis of neoplasm was made in 4 cases. Presence of hurthle cell metaplasia, hyperplastic nodules and papillary hyperplasias were responsible for the false positive diagnoses. In 24 cases neoplasms were initially missed on FNAC of which 10 cases could be detected on review while 5 cases were considered unsatisfactory. Sampling errors were mainly responsible for these false negative diagnoses. FNAC is thus an accurate and reliable diagnostic tool for management of goiters provided strict adherence to adequacy criteria are maintained.