The presence of multinucleated giant cells: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features vs the follicular variant of papillary thyroid carcinoma.

Abstract

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly described entity with an indolent clinical course as compared to the follicular variant of papillary thyroid carcinoma (FVPTC). As the cytologic features of NIFTP overlap those of the FVPTC, distinction between the two on FNA cytology poses diagnostic difficulties. This study analyzes the presence of multinucleated giant cells (MGCs). Twenty histologically confirmed NIFTP cases and 17 FVPTC cases each with a prior FNA and performed over a 2-year period were reviewed, the cytologic diagnoses compared and the number of MGCs counted. Of the 20 NIFTP cases, 55% were diagnoses as FLUS on FNA, 25% as FN/SFN and 10% as SPTC. Of the 17 FVPTC cases, 12% were diagnosed as FLUS, 53% as FN/SFN and 35% as SPTC. Fifteen (88%) FVTPC cases contained MGCs, whereas none of the 20 NIFTP cases contained MGCs. The presence or absence of MGCs may serve as an additional finding to differentiate NIFTP cases from FVTPC cases.