Minimizing the Diagnosis of "Follicular Lesion of Undetermined Significance" and Identifying Predictive Features for Neoplasia

We used proposed standard morphologic criteria as a guideline to conduct a 10-year retrospective review of thyroid fine-needle aspiration specimens that were originally interpreted as "follicular lesion of undetermined significance" and followed by surgical intervention. We sought to investigate whether the indeterminate diagnosis could be minimized by assessing various cytomorphologic features and identifying the features predictive of neoplasia. Using the standard morphologic criteria, we semi-quantitatively assessed a total of 24 cytomorphologic features in 123 aspirates and recorded an overall interpretation on completion of the review. Cyto-histologic correlation was evaluated and logistic regression model was performed to identify cytomorphologic features predictive of neoplasia. Although 32 of 123 aspirates remained in the indeterminate category, the retrospective review reclassified 64 aspirates as non-neoplasia and 27 aspirates as neoplasia. Histologic confirmation was achieved in 47 (73.4%) non-neoplastic and 15 (55.6%) neoplastic aspirates with a diagnostic accuracy of 68.1%. Furthermore, our analysis demonstrated that neoplasia is positively associated with the presence of syncytial tissue fragments, isolated micro-follicles, follicles with scalloped borders, scant cytoplasm, irregular nuclear membranes, nuclear overlapping, coarse chromatin, and increased cellularity. On the contrary, the presence of honeycombing tissue fragments, background colloid, and histiocytes inversely correlated with neoplasia. Overall, using proposed standard morphological criteria can minimize the diagnosis of "follicular lesion of undetermined significance," and allow for more accurate cyto-histologic correlation, and thereby playing a substantial role in reducing unnecessary surgical intervention. Diagn. Cytopathol. 2011; 39: 737-742. (C) 2010 Wiley-Liss, Inc.