Minimal Colloid without Atypia

S58 Conclusions: Pitfalls in the 11% of cases with a subsequent benign surgical diagnosis included follicular adenoma (1) and lymphocytic thyroiditis (2), with those showing hypercellularity and nuclear atypia, respectively. Almost half the neoplasms (47%) were less than or equal to 1.0 cm and this small size could contribute to their equivocal classification. Suspicious for papillary carcinoma in the Bethesda Reporting System has a high predictive value for papillary carcinoma (87%).

115 Modifying the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) to Accommodate Fine Needle Aspirations (FNAs) of Low Cellularity/Minimal Colloid without Atypia Abberly Lott Limbach, MD, Gregg Staerkel, MD. University of Texas MD Anderson Cancer Center, Houston, Texas Introduction: The BRSTC helps standardize thyroid FNA reporting for uniform risk assessment and follow-up. The atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) category creates a problem for FNAs with few follicular cells without atypia and minimal colloid (i.e., not enough cells for follicular neoplasm, too little colloid for a benign diagnosis). Some institutions classify these cases as “benign” with or without a comment stating the suboptimal nature, others use AUS/FLUS. In our institution, a category between benign and AUS/ FLUS, “indeterminate follicular lesion (low cellularity/minimal to no colloid), favor benign” (IND) was created. The AUS category is used for specimens with limited cellularity and nuclear or architectural atypia. This study looks at clinical follow-up for IND/AUS categories. Materials and Methods: The laboratory database was searched for IND/ AUS cases (12/1/09 e 8/1/13); medical records were reviewed for clinical follow-up. Results: In the study period, there were 3,504 thyroid FNAs with 575 cases reported as IND or AUS (see Table 1). Malignancies seen within the AUS category included follicular carcinoma (CA) (1), medullary CA (1) and papillary thyroid CA (26); for the IND category, it included metastatic renal cell carcinoma (1), follicular CA (1) and PTC (11).

Abstracts Society for Anatomic Pathology and Cytopathology - “SIAPEC”) FNA Classification Systems Sule Canberk, MD, Tugba Atasoy, MD, Gamze Kilicoglu, MD, Fugen Aker Vardar, MD, Kaan Meric, MD. Haydarpasa Education and Research Hospital, Istanbul, Turkey Introduction: Thyroid FNA (fine needle aspiration) biopsy has been widely accepted as an accurate and cost-effective tool in the management of thyroid nodules. However, management of thyroid nodules should be based on a multidisciplinary approach. For this purpose, many additional diagnostic methods have been proposed to avoid unnecessary FNA and surgery. Thyroid Imaging Reporting and Data System (TIRADS) and strain elastography (SE) has been used to make a risk assessment of the malignancy. Here, we analyzed the utility of the TIRADS system and elastography in the management of the thyroid nodules as an additional method to FNA. Materials and Methods: We present preliminary results of a prospective study which is still under progress in our institution. We evaluated 141 consecutive patients referred for FNA of a thyroid nodule. TIRADS and 6tiered and 5-tiered cytology classification groups were correlated with frequency tables and chi-square tests. ROC curve analysis was used for discrimination of a cut-off value for SE. Kruskal-Wallis variance analyses were preferred for comparing groups that reject normality. Results: TIRADS groups tested against Bethesda for determining whether they were related, showed a statistically significant relationship (PZ0.0001) (Table 1). TIRADS was also found to be related to 5-tiered systems (for SIAPEC P Z 0,0002, for Royal College P Z 0,0001). However, TIRADS did not present any statistically significant difference between diferent categories; benign-undetermined-malignant (Table 2). Emax (Elastography value), however, demonstrated a significant correlation and a cutoff point of 4 was identified for malignant, and 2,66 for benign lesions (Figure 1). Conclusions: There are a limited number of studies about TIRADS and elastography, comparing current 5- and 6-tiered FNA classification systems. The current study showed that standardization was not possible and practical, but SE showed promising results. Table 1 TIRADS

2 3 4A 4B 5

Conclusions: Although the diagnosis of AUS (3%) was low, the rate of malignancy (26%) was relatively high, whereas the more frequently diagnosed IND (13%) resulted in a lower frequency of malignancy (3%). By placing these FNAs into separate categories, the AUS category gained greater significance with an increased rate of malignancy. The IND category resulted in a risk of malignancy lower than the published risks of malignancy for AUS/FLUS and slightly above most reported risks of malignancy for a benign colloid nodule. This data supports placing aspirates of low cellularity without atypia and minimal to no colloid into a separate category from “benign” and AUS/FLUS. 116 Is it Possible to Avoid Unnecessary FNAs with the Use of TIRADS (Thyroid Imaging Reporting and Data System) and Elastogram? A Comparison Study with the 6-tiered (Bethesda System for Reporting Thyroid Cytology - “TBSRTC”) and 5-tiered (British Thyroid Association-Royal College of Physicians - “BTA/RCP” and Italian

Bethesda 1

2

3-4

5-6

8 2 20 0 0 30 (21,3%)

29 2 39 7 0 77 (54,6%)

1 1 11 5 0 18 (12,8%)

4 0 5 5 2 16 (11,3%)

Chi-square DF Significance level Contingency coefficient

42 (29,8%) 5 ( 3,5%) 75 (53,2%) 17 (12,1%) 2 (1,4%) 141 38,324 12 P Z 0,0001 0,462

Table 2 TIRADS

2-3 4A-4B-5

Bethesda category 4 or 5 No

yes

43 82 125 (88,7%)

4 12 16 (11,3%)

Chi-square DF Significance level Contingency coefficient

47 (33,3%) 94 (66,7%) 141 0,220 1 P Z 0,6388 0,039