title: Low malignancy risk of thyroid follicular lesion of undetermined significance in patients from post-endemic areas.
abstract: OBJECTIVE
  New classification of the thyroid fine-needle aspiration biopsy (FNAB) results tries to stratify the risk of malignancy of thyroid follicular lesions using 'follicular lesion of undetermined significance' (FLUS) subcategory. Clinical significance of this category in the endemic (or post-endemic) areas has not been clearly established.
  
  
  METHODS
  The aim of the study was to determine the risk of malignancy for FLUS as well as to evaluate ultrasound (US) malignancy risk features (MRF) in such nodules in comparison with 'suspicious for neoplasm' (SFN) and 'benign lesions' (BL).
  
  
  METHODS
  The US images and cytological diagnoses of 589 thyroid follicular lesions were analysed from January 2010 to July 2012. Cytological follow-up was assessed in 110 cases and surgical one in 100 cases.
  
  
  RESULTS
  FLUS was diagnosed in 340 cases (3.8% of all cytological diagnoses and 57% of thyroid follicular lesions). Altogether, clinical and/or surgical follow-up revealed thyroid cancer in 3.2% patients with FLUS nodules. Repeat FNAB led to more specific diagnosis in 74.4% of FLUS (3.5%, papillary cancers or their suspicion; 2.3%, SFN; 68.6%, BL). The histopathological examination showed thyroid cancer in 6.4% cases of FLUS and 7.0% of SFN and follicular adenoma in 8.5% of FLUS and 11.6% of SFN (NS, FLUS vs SFN). FLUS showed MRF of intermediate values between BL and SFN; SFN more often than FLUS showed at least two MRF (53 vs 30%, P<0.0001).
  
  
  CONCLUSIONS
  The risk of cancer in FLUS in areas with recently corrected iodine supply is low. In such areas, repeated biopsy leads to more precise cytological diagnosis in about 3/4 cases.
authors: Chair of Endocrinology, Department of Morphometry of Endocrine Glands, Medical University of Lodz, Lodz, Poland. dsk@tyreo.umed.lodz.pl
authors: Dorota
authors: D
authors: Słowińska-Klencka
authors: Ewa
authors: E
authors: Woźniak
authors: Martyna
authors: M
authors: Wojtaszek
authors: Bozena
authors: B
authors: Popowicz
authors: Stanisław
authors: S
authors: Sporny
authors: Mariusz
authors: M
authors: Klencki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle / Q000379:methods; D019353:Endemic Diseases; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery; D014463:Ultrasonography