Background:Subacute granulomatous thyroiditis (SGT) is an inflammatory disease that presents with different clinical and cytological characteristics. Although the diagnosis is generally made clinically, imaging methods and fine-needle aspiration (FNA) may provide assistance, particularly in atypical cases. The objective of this study is to reveal the ultrasonographic (USG) and cytological characteristics of SGT.Materials and Methods:The clinical, USG and cytological findings of 21 cases diagnosed with SGT were reviewed.Results:Ultrasonographic data was available in 20 cases. A hypoechoic thyroid nodule with irregular margins was detected in 12 of the 20 total cases. Of these, 9 cases complained about pain in the thyroid lodge and generally had unilateral lesions, heterogeneous and hypoechoic areas with indistinct margins, rather than nodular lesions, which were seen in 7 cases. Cytologically, the multinuclear giant cells (MNGCs) found in all cases were accompanied by a dirty background containing varying numbers of granulomatous structures, including isolated epithelioid histiocytes, proliferated/regenerated follicle epithelium cells and inflammatory cells and colloid.Conclusion:Though hypoechoic and heterogeneous areas with irregular margins are strongly associated with thyroiditis, SGT may also appear as painful or painless hypoechoic, solid nodules and generate challenges in differential diagnosis. Although the most remarkable characteristic observed in FNA cytology was the presence of multiple MNGCs with cytoplasm, a dirty background accompanied by mild-moderate cellularity, degenerated-proliferated follicular epithelium cells, rare epithelioid granulomas and mixed type inflammatory cells are characteristic for SGT. The assessment of these radiological and cytological findings in conjunction with clinical findings will assist in the achievement of an accurate diagnosis.

Background:Conventional medical sources recommend the use of fine needle aspiration cytology (FNAC) for single thyroid nodules and the dominant nodule in multinodular goiter (MNG). The purpose of the present study was to analyze the utility of FNAC for multiple thyroid nodules in patients with MNG and to determine the rate of malignancy in teh nondominant nodules.Materials and Methods:Our private practice performed ultrasound-guided FNAC on 1,606 patients between February 2001 and February 1, 2010. In the MNG cases, samples were taken from the dominant nodule and from trhee suspicious / nonsuspicious nodules larger than 1 cm on ultrasound. Ninety-four cases were diagnosed as ‘suspiciously malignant’(SUS) or ‘malignant’ (POS) based on FNAC. Results:The rate of an SUS / POS diagnosis was 5.7% in the dominant nodules; 2.3% of the nondominant nodules had a SUS / POS diagnosis in FNAC (p = 0.0003). Follow-up revealed malignancy in 15 (35.7%) nondominant nodules and in 27 (64.2%) dominant nodules, with 42 MNG cases undergoing surgery. X test showed a ‘p-level of 0.0003’ between the percentages of SUS / POS diagnosis in dominanat and nondominanat nodules. It was less than the significance level of 0.05. Therefore, the result was regarded to be statistically significant.Conclusions:Nondominant nodules could harbor malignancy. The risk of malignancy in nondominant nodules in MNG should not be underestimated. We have shown that the dominant nodule in patients with MNG was in fact about 2.5 times more likely to be malignant than a nondominant nodule. The use of FNAC for nondominant nodules could enhance the likelihood of detecting malignancy in an MNG.

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