[367] Fine-Needle Aspiration of Follicular Patterned Lesions of the Thyroid: Diagnosis, Management and Follow-Up According to National Cancer Institute Recommendations

WC Faquin, ZW Baloch. Massachusetts General Hospital, Boston, MA; UPENN Medical Center, Philadelphia, PA

Background: The National Cancer Institute (NCI) State of the Science Conference on thyroid fine-needle aspiration (FNA) proposed that follicular patterned lesions can be divided into two diagnostic categories; follicular lesion of undetermined significance/rule-out follicular neoplasm (FLUS/ROFN) and follicular neoplasm/suspicious for follicular neoplasm (FN/SFN). The former group can benefit from repeat FNA (RFNA) to arrive at a definite diagnosis and the latter should undergo surgical excision for histologic characterization (follicular adenoma vs. carcinoma). In this study we report the combined experience from our institutions with thyroid FNA cases that can be placed into NCI designated thyroid FNA diagnostic categories for follicular patterned lesions.
Design: The case cohort comprised of 598 cases in 436 females and 162 males (average age 55 years); as proposed by NCI 327 cases could be classified as FLUS/ROFN (diagnosis based upon presence of one or combination of the following: increased cellularity, nuclear atypia and microfollicles) and 271 as FN/SFN (diagnosis based upon presence of one or combination of the following cytologic features: monotonous cell population, microfollicles). Surgical pathology follow-up was available in 142/327 (43%) cases diagnosed as FLUS/ROFN and 169/251 (67%) as FNA/SFN.
Results: 150/327 (46%) cases classified as FLUS/ROFN underwent RFNA. The RFNA diagnoses were 101 cases benign, 13 FLUS/ROFN, 27 FNA/SFN, 7 suspicious for papillary carcinoma and 2 as papillary thyroid carcinoma. The malignancy rate on surgical excision in the RFNA group was 35% as compared to 19% without RFNA. The malignancy rate on surgical excision in cases diagnosed as FN/SFN was 21%.
Conclusions: The management of thyroid lesions diagnosed as FLUS/ROFN by RFNA is an effective way to triage patients since the malignancy rates are different in cases with or without RFNA (35% vs. 19%). The malignancy rate (21%) of cases diagnosed as FN/SPN is similar to what has been reported by other authors.
Category: Cytopathology

Monday, March 9, 2009 1:45 PM

Platform Session: Section F, Monday Afternoon