A pathologic re-review of follicular thyroid neoplasms: The impact of changing the threshold for the diagnosis of the follicular variant of papillary thyroid carcinoma

Abstract

Histopathologic criterion for follicular variant of papillary thyroid cancer (FVPTC) has only recently been utilized universally. The purpose was to determine whether, on review, these criteria would result in a change in diagnosis of follicular neoplasm (FN). A ten-year clinical cohort included patients with a diagnosis of a follicular adenoma, follicular carcinoma (FC), or FVPTC. The archived sections were re-examined by two pathologists blinded to the original diagnoses. Clinical follow-up, including ultrasonography, was carried out on all patients with a change in diagnosis. One hundred eighty-five patients met the inclusion criteria. Initially, 118 were benign, 56 were FVPTC, and 11 were FC. Overall, 46 (25%) patients had a change in diagnosis on re-review; 35 were reclassified from a benign diagnosis to a re-reviewed malignant diagnosis, with 5 reclassified as minimally invasive FC, 4 as occult PTC, and 26 (74%) as FVPTC. Of the 26 FVPTC, only 10 (38%) had undergone a total thyroidectomy (TT). The mean follow-up was 105 months (range, 24-156). None of these patients had evidence of recurrent or persistent disease. Eleven patients were reclassified to a benign diagnosis. Eight have undergone a TT, with 3 of these patients receiving I(131) ablation therapy. A third independent thyroid pathologist also reviewed the histopathologic slides of these 46 patients and concurred with the change in diagnosis in 41 of the 46 patients. Reclassification of FN increased malignant lesions from 36% to 48%. Although there have been no clinical ramifications in the patients with a changed diagnosis, the ethical issues surrounding these 46 patients are important and present a substantive quandary to the clinicians responsible for their care.