[1126] Long Term Follow-Up of Patients with Follicular Variant of Papillary Thyroid Carcinoma (FVPTC)

MB Flanagan, VA LiVolsi, ZB Baloch. Hospital of the University of Pennsylvania, Philadelphia, PA

Background: FVPTC is a distinct morphologic variant of papillary thyroid carcinoma. Its behavior is not well-characterized and guidelines for management are lacking. Our goals were to characterize cases with a histologic diagnosis of FVPTC, assess their long-term outcome, and examine utility of completion thyroidectomy (CT) in patients with FVPTC diagnosed in partial thyroidectomy (PT).
Design: 41 patients with FVPTC on surgical resection in 1997-8 were retrieved from the pathology files. Patients with concurrent malignant thyroid neoplasm other than FVPTC were excluded. Clinico-pathologic data and follow-up (thyroglobulin and/or tissue sampling) were extracted from medical records. To assess long term outcome, first diagnosis (FD) of FVPTC included all histologic data from initial diagnosis (total thyroidectomy or combined PT and CT if within 1 year). To examine utility of CT, histologic data for PT and CT within 1 year were considered separately.
Results: Patient/ tumor characteristics: Mean patient age at FD was 47.9 yrs (21.9 76.7), with male to female ratio of 9:32. FVPTC presented as a single nodule (27 patients) or multiple (12: 2 in 5, 3 in 4, 4 in 1, multiple in 2). Mean size of the dominant nodule was 1.9 cm (0.2 4.5). Tumor capsular invasion (CI) was present in 6 (2 focal), extrathyroidal extension (ETE) in 1, lymphovascular invasion (LVI) in 1, and lymph node (LN) involvement in 2 cases. Long term outcome: 25/41 cases had follow-up (thyroglobulin in 20, tissue in 1, both in 4), with mean follow-up time of 7.7 yrs (2.2 16.7). 2/25 had recurrences of FVPTC: 1) FVPTC metastasized to a rib 7.3 yrs later, and 2) a 3mm FVPTC within a follicular adenoma was found in the contralateral lobe to that with the FD 16.7 yrs later. In both, FD FVPTC was an encapsulated single nodule (2.5 cm and 2.0 cm) with no CI, ETE, LVI, or LN involvement). Utility of CT in patients with FVPTC diagnosed in PT: 17 patients with FVPTC in PT had CT within 1 year. CT showed additional FVPTC in 5 patients. No others had significant findings. None of the 17 patients had recurrences of FVPTC.
Conclusions: Clinical follow-up was available in 61% of our FVPTC patients. In our experience, FVPTC is an indolent disease, with definitive metastasis in 1/25 (4%) of these patients. The microscopic FVPTC in the contralateral thyroid lobe 16 years after FD most likely represents an incidental finding rather than metastasis. None of the CT performed soon after PT had significant additional pathology, suggesting CT may not be necessary in these cases.
Category: Head & Neck

Monday, March 9, 2009 1:00 PM

Poster Session II # 181, Monday Afternoon