Fine-needle aspiration biopsy of the thyroid: atypical cytopathological features.
OBJECTIVE
To evaluate the positive predictive value of a thyroid nodule being malignant when categorized as atypical, and to determine the prognostic implications of specific cytopathological features.


METHODS
Retrospective review of consecutive patients undergoing thyroid surgery following fine-needle aspiration biopsy (FNAB) of thyroid nodules.


METHODS
Academic teaching hospital in Toronto, Ontario.


METHODS
A total of 111 consecutive patients with atypical findings from an FNAB who underwent thyroid surgery from January 2000 to November 2005.


RESULTS
Of 111 patients included in this study, 62 (56%) were diagnosed with a thyroid malignancy on final histopathological examination. The remaining 49 patients (44%) had benign disease. When comparing patients with a postoperative diagnosis of malignancy vs those with benign disease, micronucleoli (71% vs 49%; P = .01), nuclear grooves (50% vs 31%; P = .03), and powdery chromatin (37% vs 16%; P = .01) were more frequently observed in the group with cancer. The probability of malignancy was 83% if all 3 of these features were present; 32% if none of these features was present (P = .001).


CONCLUSIONS
At our institution, when findings from a thyroid nodule FNAB sample were categorized as atypical, the positive predictive value of the nodule being malignant was 56%. In this series of patients, the presence of micronucleoli, nuclear grooves, and powdery chromatin increased the likelihood that an atypical specimen was representative of malignant disease. These features may help guide treatment of patients with atypical findings from a thyroid nodule FNAB sample.
Yehuda
Moshe
M
Department of Otolaryngology, Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5. moshe@yehuda.com
Payne
Richard J
RJ
Seaberg
Raewyn M
RM
MacMillan
Christina
C
Freeman
Jeremy L
JL
D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000453:epidemiology / Q000473:pathology*; D016606:Thyroid Nodule / Q000453:epidemiology / Q000473:pathology*