[1217] Does Tall Cell Histology Affect the Clinical Behavior of Papillary Thyroid Microcarcinoma?

ZW Baloch, K Shafique, KT Montone, VA LiVolsi. UPENN Medical Center, Philadelphia, PA

Background: Papillary thyroid microcarcinoma (PTMC) is an indolent tumor with favorable long term prognosis, however, recurrences in the neck and distant metastases have been reported. Tall cell variant of papillary thyroid carcinoma (TCV-PTC) is an aggressive variant of papillary thyroid, which can show increased propensity towards lymph node metastases, tumor recurrences and distant metastasis as compared to classic variant of papillary thyroid carcinoma. In this study we evaluated the effect of tall cell histology on the biologic behavior of PTMC.
Design: The computerized pathology files at our institution were searched for cases diagnosed as papillary thyroid carcinoma and TCV-PTC. Fourteen cases of PTMC with tall cell histology (PTMC-TCV) were identified. Clinicopathologic data and follow-up (serum thyroglobulin measurements, radiologic studies and/or additional tissue sampling) through present date were extracted from medical records and was compared with similar data from 10cases of PTMC classic variant (PTMC-CV) and 16 cases of PTMC follicular variant (PTMC-FV).
Results: PTMC-TCV presented as a single focus in 8 (57%) and as multiple foci in 6 (43%) cases(size range 0.2-1.0 cm), whereas PTMC-CV and PTMC-FV presented as single focus in 7 and 13 and as multiple foci in 3 cases each respectively (size range 0.2-1.0 cm). A higher rate of lymphovascular invasion(LVI), extrathyroidal extension (ETE) and lymph node metastases (LN-mets) was seen in PTMC-TCV as compared to PTMC-CV and PTMC-FV; LVI 28% vs. 10% and 6%, ETE 50% vs. 10% and 0% and LN-mets 28%% vs. 10% and 6%. Regional tumor recurrence was seen in 5 (5/14 36%) cases of PTMC-TCV, in 1 (1/10 10%) of PTMC-CV and in 1 (1/16-6%) case of PTMC-FV. Distant metastases were not seen in any three variants of PTMC at an average mean follow-up of 9-years.
Conclusions: In our experience, tall cell histology portends a more aggressive clinical course in PTMC cases. Therefore, this should be mentioned in the pathology report as these cases may require close clinical follow-up as compared to the cases of PTMC-CV and PTMC-FV.
Category: Head & Neck

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 169, Wednesday Morning


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