title: Atypical follicular cells with equivocal features of papillary thyroid carcinoma is not a low-risk cytologic diagnosis.
abstract: OBJECTIVE
  To determine whether or not significant differences in the risk of malignancy exist between subgroups of atypical follicular cells in The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in patients who underwent surgical resection.
  
  
  METHODS
  Between 2004 and 2009, consecutive thyroid fine-needle aspirates at our institutions with a cytologic diagnosis of 'atypical follicular cells' were retrieved and subclassified using the diagnosis and diagnostic comment as: (1) atypical follicular cells with equivocal features of papillary carcinoma [cannot exclude papillary thyroid carcinoma (PTC)] and (2) atypical follicular cells, other patterns. The risks of malignancy for excised nodules were calculated and comparisons were made between these subgroups. Categorical analysis was performed using a 2-tailed Fisher's exact test, and p < 0.05 was considered statistically significant.
  
  
  RESULTS
  A total of 7,072 thyroid fine-needle aspiration cases were retrieved, with 1,542 (21.8%) having a histologic follow-up. There were 222 (3.1%) cases of 'atypical follicular cells', with 127 (57.2%) having a histologic correlation and 33 having confirmed malignancies. Atypical follicular cells, cannot exclude PTC, have a significantly higher risk of malignancy than atypical follicular cells, other patterns (45.8 vs. 13.9%, p < 0.01).
  
  
  CONCLUSIONS
  Atypical follicular cells with equivocal features of papillary carcinoma is not a low-risk cytologic diagnosis.
authors.affiliation: Department of Pathology, University of Massachusetts Memorial Medical Center, Worcester, Mass., USA. martin.luu@umassmemorial.org
authors.forename: Martin H
authors.initials: MH
authors.lastname: Luu
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Fischer
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Stockl
authors.forename: Latha
authors.initials: L
authors.lastname: Pisharodi
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Owens
mesh_terms: D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D002291:Carcinoma, Papillary; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012306:Risk; D009626:Terminology as Topic; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D016606:Thyroid Nodule / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*