Faculty Bibliography

Introduction: Because of the indolent nature and potentially conservative treatment of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP)- an entity recently removed from the malignant papillary thyroid carcinoma (PTC) category, it is crucial to identify features of this entity pre-operatively. Our group has recently published our findings that several statistically significant associations appear to be present between cytomorphologic features and surgical diagnosis that may be used as clues to distinguish NIFTP, PTC and follicular adenoma (FA) on fine-needle aspiration (FNA). Therefore, we set out to determine the reproducibility of these results. Materials and Methods: Pre-surgical FNA slides from NIFTP (n=30), classical PTC (n=30) and FA (n=30) collected from 1/2013-8/2016 were reviewed by 7 cytopathologists blind and independently. Presence of cytomorphologic features was recorded and compared to determine concordance amongst cytopathologists. For each feature, the concordance was compared between NIFTP, PTC and FA by Fisher's Exact Test. Utilizing the majority consensus for presence or absence of each cytomorphologic feature, differences amongst NIFTP, PTC and FA presurgical FNAs were assessed for each feature by Fisher's Exact Test. Results: For all the cytomorphologic features, the concordance rates amongst the pathologists ranged between 78 to 93%. The concordance rates were similar between the NIFTP, PTC and FA groups (Table 1). Comparing each cytomorphologic feature (present/absent determined by majority consensus) amongst the NIFTP, PTC and FA groups displayed statistically significant differences for all features (Table 2). Conclusions: The current study supports our previous findings that there are cytomorphologic differences between the three surgical pathology groups-NIFTP, PTC and FA, and shows that these results are reproducible. The presence or absence of each feature viewed in combination as a profile may assist the cytopathologist in raising the possibility of NIFTP pre-operatively, potentially aiding clinicians in deciding whether a more conservative treatment plan is appropriate. (Table Presented)

TROP-2 is a type I transmembrane glycoprotein which is over-expressed in various malignancies, and is related to epithelial cell adhesion molecule (EpCAM), also called TROP-1, gp40, and KSA. In this study, we evaluated TROP-2 expression in papillary thyroid carcinoma (PTC) and compared it to other thyroid neoplastic and non-neoplastic lesions. Immunohistochemical (IHC) evaluation for TROP-2 was performed on 137 thyroid fine needle aspiration (FNA) cell blocks (CB) which included classic PTC (64), follicular variant PTC (FVPTC) (10), anaplastic thyroid carcinoma (AC) (2), medullary carcinoma (MC) (8), follicular neoplasms (FN) (8), Hurthle cell neoplasms (HCN) (9), follicular lesion of uncertain significance (FLUS) (12), and benign thyroid nodule (BTN) (24). IHC for TROP-2 expression was also performed on 331 BTN and malignant tumor tissue sections in tissue microarray (TMA). Membranous staining in >5% of tumor cells was considered positive. TROP-2 stained 61 of 64 PTC CB, 7 of 10 FVPTC CB, and 9 of 12 FLUS CB. All other cases were negative for TROP-2. TROP-2 showed a sensitivity of 95.31% and specificity of 89% for classic PTC in FNA CB. In TMA samples, TROP-2 stained 54 of 60 classic PTC cases and hence showed a high sensitivity and specificity. All BTN in CB and TMA were negative. We conclude that TROP-2 is a highly sensitive and specific IHC marker for identifying classic PTC. TROP-2 may play an important role in diagnosing classic PTC, especially in equivocal cases. This study also identifies a strong role for TROP-2 in separating PTC from BTN. Diagn. Cytopathol. 2016;44:26-31. (c) 2015 Wiley Periodicals, Inc.