Journal of Cytology & Histology

Significance of Marginal Vacuoles in Fine Needle Aspiration Cytology of Diffuse Thyroid Swelling

Abstract

Bamanikar S, Bamanikar A, Nair R, Chandanwale S, Kumar H and Buch A

Assessment of thyroid swelling by Fine needle aspiration cytology (FNAC) is an established first-line diagnostic test. Marginal vacuole (MVs) in fine needle aspiration (FNA) smears stained by Leishman’s stain have been described as a characteristic feature of thyrotoxic goiter, but was also found in various nontoxic thyroid lesions. Although the exact nature of these MVs is not known, on electron microscopy they are seen as dilated endoplasmic reticulum which represents active pinocytic vacuoles containing colloid. The aim of the study was to examine the presence of MVs in diffuse thyroid enlargement and evaluate the strength of association between MVs, thyroid function status and cytological diagnosis. We examined seventy six cases of diffuse thyroid swelling. Cytomorphological features were observed with special attention to MVs and their density was graded as scant, moderate and abundant. The strength of association was studied by applying the Chi-square test; a P ≤ 0.05 was taken significant. Abundant MVs were not associated with hypothyroidism in this study; 73.3% of these cases were hyperthyroid. Interestingly, abundant MVs in thyroid FNACs were seen in cases of primary hyperplasia and Hashimoto's thyroiditis. The presence of abundant/moderate MVs correlated significantly with primary hyperplasia and the absence of abundant MVs was significant in colloid goiter. Scant MVs in diffuse goiters were not found to correlate with thyroid function. Thus, hormonal evaluation is essential in all diffusely enlarged goiters showing prominent MVs in order to rule out hyper functioning goiter.