title: Rates of malignancy in incidentally discovered thyroid nodules evaluated with sonography and fine-needle aspiration.
abstract: OBJECTIVE
  The purpose of this study was to compare the rate of malignancy in thyroid nodules discovered incidentally on magnetic resonance imaging, computed tomography, and sonography with the rate of malignancy in nonincidentally discovered nodules.
  
  
  METHODS
  All thyroid sonographic and fine-needle aspiration (FNA) procedures performed during a 6-month period were retrospectively reviewed. Study indications were categorized as incidental (thyroid nodules found on magnetic resonance imaging, computed tomography, or sonography performed for nonthyroid indications) or nonincidental (studies prompted by abnormal physical examination findings or laboratory values or signs or symptoms suggestive of thyroid disease). Rates of malignancy in patients with incidentally discovered nodules were compared with rates in patients with nonincidental thyroid abnormalities by the Fisher exact test.
  
  
  RESULTS
  Of 225 thyroid sonographic studies, 35 (16%) were performed for incidentally discovered thyroid nodules, and 190 (84%) were performed for evaluation of nonincidental thyroid abnormalities. A total of 21 patients (60%) in the incidental group and 90 patients (47%) in the nonincidental group underwent FNA. The rate of malignancy in nodules examined by biopsy in the incidental group was 17% compared with 3% in the nonincidental group (P = .020). Patient sex, multiplicity of nodules, nodule size, echo texture, and presence of calcifications did not differ significantly between the groups. The mean age of patients in the incidental group was significantly higher (61 versus 51 years; P = .007); however, advanced age was not associated with a greater rate of malignancy.
  
  
  CONCLUSIONS
  This study identified an unexpectedly high rate of malignancy in incidentally discovered thyroid nodules, suggesting that incidentally discovered thyroid nodules should be evaluated with follow-up thyroid sonography and FNA.
authors.affiliation: Department of Radiology, Lenox Hill Hospital, 100 E 77th St, New York, NY 10021, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Liebeskind
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Sikora
authors.forename: Arnold
authors.initials: A
authors.lastname: Komisar
authors.forename: David
authors.initials: D
authors.lastname: Slavit
authors.forename: Karen
authors.initials: K
authors.lastname: Fried
mesh_terms: D044963:Biopsy, Fine-Needle / Q000379:methods*; D018276:Carcinoma, Medullary / Q000000981:diagnostic imaging / Q000473:pathology; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography