Correlation between indeterminate aspiration cytology and final histopathology of thyroid neoplasms.
BACKGROUND
Of all thyroid nodules assessed by fine needle aspiration cytology (FNAC), 10-20% are classified as indeterminate/atypical. Traditionally, this group is considered to primarily represent follicular neoplasia. We hypothesize that papillary carcinoma accounts for a significant proportion of lesions classified as "atypical" on FNAC.


METHODS
This retrospective study includes 228 patients who had an atypical FNAC result and who were subsequently found to have a malignancy on histologic examination of the excised thyroid lesion. Patients with papillary microcarcinomas, defined as lesions less than 10-mm diameter, were excluded. The study period was from 1987 to 2005. The patients were divided chronologically into 3 groups (n = 76) for analysis: group 1, December 1987-March 1997; group 2, July 1997-October 2002; and group 3, October 2002-December 2005.


RESULTS
Age- and sex-distribution of the 3 groups were not significantly different. Median nodule size of group 3 was significantly smaller. The distributions of histopathology of the 3 time periods were significantly different overall (P = .0325). Prevalence of papillary carcinoma was not statistically significant (33/76 vs 34/76 vs 46/76; P = .0636), but showed a statistical significant trend to increase over time (P = .0349). Prevalence of follicular variant papillary carcinoma was also found to be significantly different between the groups (7/76 vs 12/76 vs 19/76; P = .0320; P = .0349).


CONCLUSIONS
Papillary carcinoma accounted for most histopathologically confirmed cancers that had an atypical cytology. Papillary cancer in this group of patients trended up, probably due to a significant increase in the diagnosis of follicular variant of papillary cancer.
University of Sydney Endocrine Surgical Unit, Royal North Shore Hospital, Sydney, Australia.
Tony
T
Pang
Catharina
C
Ihre-Lundgren
Anthony
A
Gill
Todd
T
McMullen
Mark
M
Sywak
Stan
S
Sidhu
Leigh
L
Delbridge
D000293:Adolescent; D000328:Adult; D044963:Biopsy, Fine-Needle / Q000379:methods*; D001707:Biopsy, Needle / Q000379:methods*; D002291:Carcinoma, Papillary / Q000235:genetics / Q000473:pathology / Q000601:surgery*; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D014644:Genetic Variation; D006042:Goiter / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery*; D016606:Thyroid Nodule / Q000473:pathology; D013965:Thyroidectomy / Q000379:methods*