title: The cytological diagnosis of a 'benign thyroid lesion': is it a real safe diagnosis for the patient?
abstract: OBJECTIVE
  In fine needle aspiration cytology (FNAC), the category of benign thyroid lesions (BTL), which constitutes 65-70% of all thyroid FNAC, and can be correctly diagnosed by morphology alone, is an important entity. A diagnosis of BTL denotes a lesion managed with follow-up unless found in conjunction with compressive symptoms. Although this diagnosis can be quite simple, there are cases in which the scant cellular or colloid component may pose diagnostic issues. Herein, we describe the experiences of evaluating BTL at two large academic institutions. We evaluated the clinical importance of a correct diagnosis of BTL to define the exact inherent risk of a false-negative result (FNR).
  
  
  METHODS
  From January 2008 through to June 2013, 506 (3.6%) out of 15 850 patients with BTL underwent surgery. All nodules were sampled under sonographic guidance (US) and processed either with liquid-based cytology (LBC), Diff-Quik® smears or alcohol-Papanicolaou staining methods.
  
  
  RESULTS
  The histological follow-up of 506 BTL series included 493 benign and 13 malignant lesions. The latter group included four follicular carcinomas (FC), two classic variants of papillary thyroid carcinoma (PTC), one macrofollicular PTC and six follicular variants of PTC (FVPC). The malignancy rate for the BTL category was 2.5%.
  
  
  CONCLUSIONS
  When diagnosed by expert cytopathologists, BTL represents a robust diagnosis and might reduce the number of FNR. Additional diagnostic experience and a large case series could enable cytopathologists to recognise all the morphological entities of BTL. An important additional aid is the extensive sampling of the lesions to reduce issues related to a low cellularity.
authors.affiliation: Anatomic Pathology and Histology, Università Cattolica del Sacro Cuore, "Agostino Gemelli" School of Medicine, Rome, Italy.
authors.forename: E D
authors.initials: ED
authors.lastname: Rossi
authors.affiliation: Anatomic Pathology and Histology, Università Cattolica del Sacro Cuore, "Agostino Gemelli" School of Medicine, Rome, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Bizzarro
authors.affiliation: Anatomic Pathology and Histology, Università Cattolica del Sacro Cuore, "Agostino Gemelli" School of Medicine, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Fadda
authors.affiliation: Endocrinology, Università Cattolica del Sacro Cuore, "Agostino Gemelli" School of Medicine, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pontecorvi
authors.affiliation: Endocrinology and Metabolic Diseases, Mayo Clinic, Jacksonville, FL, USA.
authors.forename: V
authors.initials: V
authors.lastname: Bernet
authors.affiliation: Pathology and Laboratory Medicine, Mayo Clinic, Jacksonville, FL, USA.
authors.forename: A
authors.initials: A
authors.lastname: Nassar
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle / Q000379:methods; D002277:Carcinoma / Q000175:diagnosis / Q000473:pathology; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000166:cytology / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000473:pathology; D016606:Thyroid Nodule / Q000175:diagnosis* / Q000473:pathology*; D055815:Young Adult
keywords: benign lesion; liquid-based cytology; thyroid carcinoma; thyroid cytology