Endocrine Abstracts

Introduction: Differentiated thyroid carcinoma (DTC) is the most common endocrine neoplasm and its rate it’s constantly increasing. Papillary thyroid carcinoma (PTC) represents 87% of all DTC and its incidence is raising at 89%. The thyroid carcinoma preoperative diagnosis consists in fine-needle ago aspiration (FNAB). However in the diagnostic cytology there actually is a ‘grey zone’, the ‘follicular lesion of indeterminate significant or suspicious for follicular neoplasm’ (Thy3 and Thy4 by British Thyroid Association). By date molecular analysis is coming a powerful diagnostic tool. The most common mutation found in PTC is B-RAF V600E detected in 50% of all PTC at the definitive histological diagnosis. There are, then, other mutations in the B-RAF as the K601E that in vitro demonstrates an oncogenic activity lower than V600E: the V600E kinase activity has a 2.5 times greater than the K601E that has been identified in follicular adenomas and, more rarely, in follicular carcinomas.

Purpose: The study purpose was to evaluate, in our Ligurian population, the effectiveness of surgery not only with the cytological diagnosis but also with the investigation of molecular genetics.

Materials and methods: patients (14 males and 41 females, average age 53 years) were evaluated between January and November 2013 with indeterminate cytological diagnosis. The FNAB material was fixed with cytofix on glass slides from which one was used for molecular diagnostics.

Results: The presence of B-RAF mutations was similar in Thy3 and Thy4 lesions (41% of Thy3 and 35% of Thy4). A B-RAF mutation was detected in 38% of all cases, 8% of these patients were males and 92% females. In 85% of cases, the mutation identified was the B-RAF V600E and in 15% of cases the B-RAF K601E. Of the cases in which a B-RAF mutation was detected, 15% were benign at the definitive histology, 85% of cases showed DTC (82% PTC and 18% follicular variant PTC) and no follicular neoplasm was detected. All B-RAF mutated cases with benignant histology were B-RAF K601E ones. Of those cases without B-RAF mutations which were carcinomas on definitive histology 45% were follicular carcinomas, 11% medullar carcinomas, 22% follicular variant PTC, 11% PTC and 11% trabecular neoplasm. Only considering classical variant PTC in 91% of cases there were correspondence between cytological diagnosis and definitive histology (in 9% of cases there were not B-RAF mutation neither at cytology neither at histology).

Conclusions: The presence of the B-RAF V600E mutation in our population suggests that a more aggressive surgical approach should be undertaken, a conviction that has already been expressed in the literature. The B-RAF V-600E mutation is present in the cytological material only in those patients with final histological diagnosis of PTC. However, in our limited number of cases, no correlation emerged between indices of malignancy and the B-RAF K601E mutation. In the course, it is a retrospective study to determine if patients carriers B-RAF V600E mutation have a worse outcome compared with WT ones.