Endocrine Abstracts

Introduction: Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS) of Bethesda system for reporting thyroid cytopathology has emerged as most controversial category due to its heterogeneity and inconsistent usage. Initially associated risk of malignancy was estimated to be about 5–15%, but eventually different results have been obtained across institutions due to variable follow-ups and interpretation. The objective of this study was to determine the risk of malignancy for nodules classified as atypical of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS) and to study the predictive factors of malignancy.

Materials and methods: For this we conducted an analytical cross-sectional study including all patients presenting a nodule or nodular goiter admitted during the year 2012–2018 to the endocrinology department of the Ibn Rochd University Hospital of Casablanca and having benefited from a cytopuncture then a thyroid surgery. All nodules diagnosed as AUS/FLUS during a thyroidal cytosis performed between 2012 and 2018 were examined retrospectively. Clinical data, ultrasound characteristics and final pathological findings were recorded. After further exclusion, only surgically operated nodules were included in the final analysis. Clinical and ultrasound characteristics were examined to determine the predictive factors for malignancy.

Results: During the study period, 198 nodules were analyzed, of which 89 were diagnosed as AUS/FLUS so a prevalence of 45%. The median age of our patients was 56 years (30–68) with a clear female predominance. No patient had cervical radiation antecedents or familial thyropathy. Of the nodules operated on, 63% had malignant histology. The main predictors of malignancy were age >55 years, hard nodule consistency (P<0.001), isthmic localisation (P<0.001), and microcalcifications on ultrasonography (P<0.001).

Conclusions: According to our study, the overall cancer rate of nodules diagnosed as AUS/FLUS was high, especially in patients>55 years old, with nodules of hard consistency, isthmic site with microcalcifications on ultrasound. It is therefore suggested that the current recommendations be re-examined in order to establish more specific criteria for a better therapeutic orientation.