Comparison of ultrasonography features and malignancy rate of toxic and nontoxic autonomous nodules: a preliminary study.
OBJECTIVE
When a scintigraphically autonomous nodule does not produce thyroid hormones enough to suppress serum thyrotrophin, it is generally defined as nontoxic autonomous nodule. In this study, we aimed to compare clinical and ultrasonographical (US) features and cytological and histopathological results of toxic and nontoxic autonomous nodules.


METHODS
Patients who underwent thyroidectomy and were evaluated with technetium-99m-pertechnetate scintigraphy preoperatively in our institution between May 2008 and December 2014 were identified from medical records. Among these, treatment naïve patients with scintigraphically autonomous thyroid nodules were chosen and classified into toxic (hyperthyroid) and nontoxic (euthyroid) groups. The demographic data, preoperative US features of the nodules, fine needle aspiration biopsy and histopathological results were analyzed.


RESULTS
There were 170 (89.0%) patients with toxic and 21 (11.0%) patients with nontoxic autonomous nodules. A total of 258 scintigraphically autonomous nodules were analyzed among which 227 were clinically functional (toxic) and 31 were clinically euthyroid (nontoxic). Echogenity, texture, marginal irregularity, presence of halo and macrocalcification were similar in toxic and nontoxic autonomous nodules. Toxic autonomous nodules were significantly bigger and had a significantly higher rate of microcalcification compared to nontoxic ones (p = 0.001 and p = 0.025, respectively). There was no significant difference in terms of cytological diagnosis between toxic and nontoxic autonomous nodules (p = 0.052). Atypia of undetermined significance/follicular lesion of undetermined significance cytology was significantly higher in nontoxic group (p = 0.01). 20 (8.8%) of 227 toxic and 2 (6.5%) of 31 nontoxic autonomous nodules were malignant (p = 0.59). Considering all nodules regardless of the thyroid function, 8.5% of autonomous nodules was malignant.


CONCLUSIONS
US features and malignancy potential of nontoxic autonomous nodules resemble toxic autonomous nodules. Lower diameter suggests that they can represent a preliminary stage of toxic ones and have potential of toxicity when get bigger in size. There is still a considerable risk of malignancy risk in autonomous nodules whether toxic or not.
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Ahmet
A
Dirikoc
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Sefika Burcak
SB
Polat
Department of Nuclear Medicine, School of Medicine, Ankara Yildirim Beyazit University, Ankara, Turkey.
Zuhal
Z
Kandemir
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Cevdet
C
Aydin
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey. sendidem2002@yahoo.com.
Didem
D
Ozdemir
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Fatma Dilek
FD
Dellal
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Reyhan
R
Ersoy
Department of Endocrinology and Metabolism, School of Medicine, Ataturk Egitim ve Arastirma Hastanesi, Ankara Yildirim Beyazit University, Ankara, Turkey.
Bekir
B
Cakir
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013963:Thyroid Hormones / Q000378:metabolism; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D014463:Ultrasonography; D055815:Young Adult
D013963:Thyroid Hormones
Nontoxic autonomous nodule; Thyroid fine needle aspiration; Thyroid malignancy; Toxic nodule