title: BRAFK601EMutation in a Follicular Thyroid Adenoma: A Case Report.
abstract: BRAF mutations represent the most common genetic alteration in papillary thyroid carcinoma (PTC). The p.V600E mutation is specific for the classic and tall-cell variants of PTC and has been associated with a more aggressive biologic behavior. On the other hand, the p.K601E mutation is peculiar to the follicular variant of PTC, and seems to be a favorable prognostic indicator. A 12-year-old boy presented with a 10-mm left-sided thyroid nodule. Fine-needle aspiration cytology reported the lesion as suspicious for a follicular neoplasm (Bethesda category IV). The patient underwent lobectomy, and histopathology revealed a follicular adenoma with normal surrounding tissue. The cytological smear was found to be positive for BRAF p.K601E mutation, and this was later confirmed on the corresponding paraffin block. This case was independently revised by 4 expert pathologists, all of whom confirmed the benign nature of the thyroid lesion. This article describes the presence of a BRAF mutation in a benign thyroid lesion. To the authors' knowledge, this is the fourth case of follicular adenoma carrying BRAFK601Ereported in literature to date. BRAFK601Emutation can occur in benign thyroid lesions. This finding, in the context of the current literature and the recently proposed reclassification of the noninvasive encapsulated follicular variant of papillary thyroid carcinoma into a benign lesion, confirms the importance of preoperative BRAF p.K601E testing in offering patients a tailored treatment plan and avoiding overtreatment.
authors.affiliation: 1 University of Pisa, Pisa, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Macerola
authors.affiliation: 2 University Hospital of Pisa, Pisa, Italy.
authors.forename: Liborio
authors.initials: L
authors.lastname: Torregrossa
authors.affiliation: 2 University Hospital of Pisa, Pisa, Italy.
authors.forename: Clara
authors.initials: C
authors.lastname: Ugolini
authors.affiliation: 1 University of Pisa, Pisa, Italy.
authors.forename: Sohail
authors.initials: S
authors.lastname: Bakkar
authors.affiliation: 1 University of Pisa, Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Vitti
authors.affiliation: 3 Catholic University, Foundation Agostino Gemelli University Hospital, Rome, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Fadda
authors.affiliation: 1 University of Pisa, Pisa, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Basolo
mesh_terms: D000236:Adenoma / Q000235:genetics*; D002648:Child; D006801:Humans; D008297:Male; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D016606:Thyroid Nodule / Q000235:genetics*
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF K601E; BRAF mutation; follicular adenoma; thyroid cancer; thyroid pathology