[389] Root Cause Analysis for False Suspicion of Papillary Thyroid Carcinoma: Review of 22 Cases.

Xin Jing, Claire C Michael. University of Michigan, Ann Arbor

Background: The Bethesda Sysyem for Reporting Thyroid Cytopathology (BSRTC) demonstrtes the criteria of suspicious for malignancy (SFM) and recommends judicious use of this diagnostic category so that an ideal positive predictive value can be achieved. Suspicious for papillary thyroid carcinoma (SPTC) represents the majority of SFM cases. The current study was undertaken to address the root causes for false SPTC.
Design: We retirieved a total of 22 aspirates in which the original cytologic interpretation of SPTC was rendered and the corresponding histology revealed non-PTC. The retrieved aspirates were retrospectively reviewed along with the corresponding surgical specimens. Morphological features were assessed and recorded.
Results: The corresponding histology of the 22 aspirates interepreted as SPTC revealed 16 nodular hyperplasia and 6 follicular adenoma. Ten aspirates were moderately cellular and 12 aspirates were hypocellular. Ten aspirates contained moderate amount of colloid. Scant or no colloid presented in 12 aspirates. Various proportions of monolayer honeycomb sheets, intact follicles and microfollicles were appreciated among all aspirates. Focal syncytium was seen in one aspirate. Conspicuous fragments of fibrocollagenous tissue with entrapped follicular cells were detected in one aspirate. Elongate or spindel cells presented in 8 aspirates and some were accompanied by histiocytes. Thin, intranuclear grooves presented focally in all aspirates and some grooves appeared incomplete. The grooves were noted mainly in rounded nuclei, as well as nuclei of the entrapped follicular cells and the elongate or spindle cells aforementioned. Rare intranuclear inclusions were detected in two aspirates. Nuclear paller was rarely seen. Presence of mild nuclear atypia including nuclear molding, nuclear enlargement, irregular nuclear membrane was minimal among all aspirates.
Conclusions: Based on retrospective cytologic review and histology correlation, the following contributed to false suspicion of SPTC:
1) Fragments of fibrocollagenous tissue with entraped follicular cells were micinterpreted as fibrovascular cores.
2) Misinterpretation of the the enlongate or spindel cells that actually represented atypical cyst lining cells.
3) Overinterpretation of suboptimal intranuclear grooves noted in the nuclei with minimal diagnostic features of PTC
4) Overinterpretation of rare intranuclear inclusions in the absence of other diagnostic features of PTC
Category: Cytopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 55, Wednesday Afternoon


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