title: Critical Pitfalls in the use of BRAF Mutation as a Diagnostic Tool in Thyroid Nodules: a Case Report.
abstract: Thyroid fine-needle aspiration (FNA) cytology is the primary tool for the diagnostic evaluation of thyroid nodules. BRAF mutation analysis is employed as an ancillary tool in indeterminate cases, as recommended by the American Thyroid Association management guidelines. Hereby, we report the case of a 73-year-old woman who presented an 8-mm-size, ill-defined, left thyroid nodule. FNA resulted "suspicious for papillary thyroid carcinoma". BRAF mutation status was analyzed, and somatic BRAF (V600E) mutation identified. The patient underwent a total thyroidectomy. At histological examination, the nodule was composed of Langerhans cells, admixed with many eosinophils. A final diagnosis of Langerhans cell histiocytosis of the thyroid was made. Our case emphasizes the critical diagnostic pitfalls due to the use of BRAF (V600E) mutation analysis in thyroid FNA. Notably, BRAF (V600E) mutation is common in melanoma, colorectal carcinoma, lung carcinoma, ovarian carcinoma, brain tumors, hairy cell leukemia, multiple myeloma, and histiocytoses. Therefore, in cases of indeterminate FNA with unclassifiable atypical cells BRAF (V600E) mutated, the possibility of a localization of hystiocytosis or a secondary thyroid malignancy should be taken into account.
authors.affiliation: Pathology Unit, Arcispedale Santa Maria Nuova-IRCCS, Viale Risorgimento 80, 42123, Reggio Emilia, Italy.|Department of Morphology, Surgery and Experimental Medicine and LTTA Centre, University of Ferrara, Ferrara, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Kuhn
authors.affiliation: Pathology Unit, Arcispedale Santa Maria Nuova-IRCCS, Viale Risorgimento 80, 42123, Reggio Emilia, Italy.
authors.forename: Moira
authors.initials: M
authors.lastname: Ragazzi
authors.affiliation: Endocrinology Unit and Thyroid Diseases Center, Arcispedale S. Maria Nuova-IRCCS, Reggio Emilia, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Zini
authors.affiliation: Otolaryngology Unit, Arcispedale S. Maria Nuova-IRCCS, Reggio Emilia, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Giordano
authors.affiliation: Molecular Biology Laboratory, Arcispedale S. Maria Nuova-IRCCS, Reggio Emilia, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Nicoli
authors.affiliation: Pathology Unit, Arcispedale Santa Maria Nuova-IRCCS, Viale Risorgimento 80, 42123, Reggio Emilia, Italy. SIMONETTA.PIANA@ASMN.RE.IT.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Piana
mesh_terms: D000368:Aged; D044963:Biopsy, Fine-Needle; D004252:DNA Mutational Analysis; D003951:Diagnostic Errors; D005260:Female; D006646:Histiocytosis, Langerhans-Cell / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D016606:Thyroid Nodule / Q000175:diagnosis* / Q000235:genetics
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF mutation; FNA; Histiocytosis; Langerhans cells; Thyroid