Thyroid cytology and risk of thyroid cancer: differences among indeterminate specimens.
OBJECTIVE
To assess the potential for stratification of indeterminate cytologic findings on fine-needle aspiration (FNA) of thyroid nodules in an effort to improve therapeutic strategies.


METHODS
We attempted to determine the malignant risk associated with various indeterminate FNA cytologic patterns by correlation of specimens with the final histologic diagnosis. For this analysis, we identified 294 computerized medical records of surgically treated thyroid nodules during a 5-year period at our institution with the corresponding FNA cytology reports available.


RESULTS
Of the 294 surgical cases, 162 with a positive or indeterminate cytologic report were selected, reviewed, and classified. Of 52 patients with positive cytologic findings on FNA, 51 (98%) had a final histologic report of a malignant thyroid nodule. Of 110 patients with indeterminate specimens, 30 (27%) had a final histologic diagnosis of thyroid carcinoma. The presence of nuclear atypia was predictive of thyroid carcinoma in 75% of patients, a Hürthle cell cytologic pattern was associated with a malignant thyroid nodule in 33%, and a hypercellular smear was suggestive of malignant involvement in 26% of cases. The lowest rate of malignant potential was associated with cytologic microfollicular and scant colloid alone subtype (6%).


CONCLUSIONS
The results of this study show that indeterminate thyroid cytologic specimens can be subdivided into groups with different malignant risks. A microfollicular cytologic pattern in the absence of a hypercellular smear or nuclear atypia does not support a recommendation of surgical treatment. A malignant cytologic diagnosis has a high positive predictive value for detection of thyroid cancer.
Deandrea
Maurilio
M
Division of Endocrinology, Centro per le Malattie della Tiroide, Ospedale Mauriziano Umberto I, Torino, Italy.
Motta
Manuela
M
Divito
Lidia
L
Mormile
Alberto
A
Gallone
Gabriella
G
Grassi
Aurora
A
Pellerito
Riccardo
R
Nasi
PierGiorgo
P
Torchio
Bruno
B
Garberoglio
Roberto
R
Fonzo
Domenico
D
D044963:Biopsy, Fine-Needle; D006801:Humans; D011237:Predictive Value of Tests; D012306:Risk; D013959:Thyroid Diseases / Q000473:pathology*; D013961:Thyroid Gland / Q000166:cytology / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology*