MON-LB095 Thyroid Nodule Localization as a Predictor Factor for Malignancy

Background: Thyroid ultrasound (US) is a key in evaluation of thyroid nodules. Judicious use of thyroid US is helpful to choose the right nodules for further evaluation by Fine needle aspiration biopsy (FNAB) and to prevent unnecessary invasive procedures. Here are few features that have been found to be associated with higher risk of malignancy. Microcalcifications within the nodule, Solid structure, size, irregular margins, hypoechogenic, lobulated, infiltrative nodules with heterogenous echo charterers and the nodules that are taller than wide have all been found to have independent associations with increased risk of malignancy. A previous study (1) showed that nodules in the upper lobe of the thyroid had higher risk of malignancy compared to nodules in the lower lobe. In another study (2) nodules located in the mid pole and upper pole of the thyroid gland were found to be more likely to be malignant compared to the lower pole. Methods: We did a retrospective study looked at 50 consecutive nodules proven to be malignant by surgical histology at our clinic between 2011-2016. Subsequently we looked at the cohort of nodules found to be benign by FNAB in the same period of time and chose 50 cases that matched the age of the patient with malignancy and the sized of the malignant nodules. We reviewed the location of the nodules in the thyroid gland, Upper vs Lower to see if there is any associated between malignant nodules and location. Assignment of the nodules to the upper vs lower pole was done by comparing the distance between the superior and inferior poles of the nodules and the corresponding pole of the gland. Result: Out of the 50 malignant nodules, 34 were located in the upper lobe (68%) and 16 were located in the lower lobe (32%). Out of 50 benign nodules, 9 were located in the upper lobe (18%) and 41 were located in the lower lobe (82%). The odds of malignant nodules to be located in the upper lobe were 9.6 times more than the odds in the lower lobe. P = <0.001. Conclusion: There is no single Ultrasound that would be diagnosed for thyroid cancer. Combination of ultrasound findings would be help identify the nodules with increased risk of malignancy and be a guide to choose the nodules that need to be biopsied. Although this study lacks power but a preliminary conclusion can be made that the location of the nodule in the thyroid gland can be associated with different risks for malignancy and may be included in the evaluation of the nodules. Finding in the study is in accordance with the finding in the previous studies (1), (2) References: 1- Thyroid nodule location on ultrasonography as a predictor of malignancy. Zhang, F et al: Endocrine Practice; 2018 Nov. ahead of print. https://doi.org/10.4158/ep-2018-0361. 2- Is thyroid nodule location associated with malignancy risk. Valeria Ramundo et al: Ultrasonography; EPUB ahead of print. https//doi.org/10.4366/usg.18050 Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.