Potential pitfalls for false suspicion of papillary thyroid carcinoma: A Cytohistologic Review of 22 Cases

Abstract

To evaluate the diagnostic pitfalls attributing to false suspicious interpretation of papillary thyroid carcinoma (PTC), we performed a retrospective cytohistologic review of thyroid nodules diagnosed as suspicious for papillary carcinoma with histology-proven false suspicion of PTC. A total of 22 thyroid fine needle aspirates along with the corresponding surgical specimens were reviewed. The presence and/or absence of PTC-associated morphologic features and their mimics were evaluated. One aspirate showed papillary-like fragments with honeycomb architecture. One aspirate contained rare syncytial-type fragments which were accompanied by honeycomb sheets of follicular cells and moderate amount of colloid. Intranuclear grooves presented occasionally in virtually all 22 aspirates. The grooves were noted mainly within round nuclei and appeared thin and/or incomplete. Rare intranuclear pseudoinclusions were detected in one otherwise benign-appearing aspirates. Eight aspirates contained various numbers of histiocytes, as well as atypical polygonal, epithelioid, elongate, or spindle cells in which intranuclear grooves were occasionally seen. Conspicuous fragments of fibrocollagenous tissue with entrapped follicular cells were detected in one aspirate. The corresponding histological specimen revealed counterpart of the cytological findings described. Other features associated with PTC were inconspicuous. The findings demonstrated that the following factors may contribute to the false suspicion of PTC: (1) misinterpretation of papillary-like tissue fragments with honeycomb arrangement and fragments offibrocollagenous tissue with entrapped follicular cells; (2) overinterpretation of suboptimal intranuclear grooves and rare intranuclear pseudoinclusion in the absence of the other features of PTC; (3) misinterpretation of the polygonal, epithelioid, elongate, or spindle cells that actually represented atypical cyst lining cells.

Trends in Thyroid Fine-Needle Aspiration Cytology Practices: Results From a College of American Pathologists 2016 Practice Survey

“…Examples of reassignment that might affect these values is reporting specimens with Hürthle cells in cases of chronic lymphocytic thyroiditis and reactive processes, which can show some nuclear features of papillary carcinoma, as benign rather than SFM, and reporting cases with some microfollicles (as opposed to those with a prominent microfollicular pattern) as benign rather than SFN/FN. Jing and Michael 9 found that Hashimoto thyroiditis can be misinterpreted as suspicious for papillary thyroid carcinoma because of the presence of nuclear inclusions and grooves in oncocytes, a pitfall also noted by Baloch and Livolsi. 10 If these changes are due to shifts in the use of cytology terminology, then these findings are consistent with a significantly greater number of laboratories in 2016 having implemented TBSRTC than those surveyed in 2011 (P , .001), and many 2011 surveyed laboratories had indicated that they planned to adopt that terminology in the near future.…”

Thyroid Bethesda Category AUS/FLUS in Our Microscopes: Three-Year-Experience and Cyto-Histological Correlation

“…In the non-neoplastic resections, six cases of thyroiditis and two cases of hyperthyroidism were diagnosed. Those non-neoplastic entities are well recognized for cytomorphological pitfalls [17,18].…”

How should a follicular adenoma with papillary architecture be classified on thyroid FNA? Case report with histological correlation

“…Therefore, the importance of a careful microscopic evaluation of nuclear features cannot be overemphasized. Multinodular goitre with degenerative changes, Hashimoto thyroiditis with hyperplastic/reactive areas and follicular adenoma may all display a papillary pattern, which is also common when large‐bore needles are used . However, the fibrovascular cores of true papillary fronds are lacking in nodular goitre aspirates, whereas, in Hashimoto thyroiditis, the inflammatory background may aid the correct cytological diagnosis .…”