The Clinical Significance of Atypia in Thyroid Fine-Needle Aspiration

Kim, Jae Won; Kim, Bo Mook; Lee, Dong Youl; Kim, Young Mo; Chu, Young Chae; Park, In Suh; Cho, Young Up

Abstract

BACKGROUND AND OBJECTIVES
Fine-needle aspiration cytology (FNAC) of thyroid nodules has become the primary diagnostic tool in the evaluation of thyroid nodules. However, the diagnostic utility of thyroid cytology may be limited by the presence of atypical cytologic patterns. In patients with atypical cytology in FNAC, the treatment concept is not established. The purpose of this study is to correlate subcategories of atypical cytology with final histologic diagnosis and help determining treatment concept of thyroid nodule.
SUBJECTS AND METHOD
Retrospectively, we analysed 143 specimens of patients with atypical cytology in preoperative FNAC, who underwent thyroidectomy from May 1996 to July 2005 at the Department of Otolaryngology and Surgery, Inha University Hospital. We divided atypical cytology into six groups by its cytologic characteristics and correlated those with final histologic diagnosis.
RESULTS
Among 143 specimens with atypical cytology, there were 97 cases (67.8%) in follicular neoplasm with nuclear atypia (FNA) group, 2 cases (1.4%) in follicular neoplasm without nuclear atypia (FNS) group, 13 cases (9.1%) in nodular hyperplasia with nuclear atypia (NHA) group, 23 cases (16.1%) in possibility of papillary carcinoma (PP) group and 5 cases (3.5%) in thyroiditis with nuclear atypia (TA) group and 3 cases (2.1%) in atypical cells (AC) group. Of 97 cases in FNA group, 29 cases (29.9%) were malignant. Malignant cases in NHA and PP groups were 11 cases (47.8%) and 3 cases (23.1%), respectively. But, not all groups have a statistically significant high incidences of malignant pathologic result. Of 29 cases diagnosed as malignant in the FNA group, only 1 case (3.4%) had lymph node metastasis in final pathologic result. Also in NHA and PP groups, only 1 case (NHA : 33.3%, PP : 9.1%) had metastatic lymph nodes. Three cases (10.3%) showed recurrence postoperatively of the 29 cases diagnosed malignant in the FNA group. In PP group, one case (9.1%) revealed recurrence postoperatively. No statistical differences existed between all groups for lymph node metastasis and recurrence.
CONCLUSION
Surgery should be considered in FNA, NHA and PP groups. The extent of resection should be determined by frozen section intraoperatively.