Digital image-assisted quantitative nuclear analysis improves diagnostic accuracy of thyroid fine-needle aspiration cytology

Abstract

Background: Thyroid fine-needle aspiration (FNA) plays a key role in triaging thyroid nodules. Yet many cases are assigned to indeterminate categories. The new category “noninvasive follicular thyroid neoplasm with papillary-like features” (NIFTP) complicates thyroid cytology. Digital image-derived nuclear measurements might objectively distinguish papillary thyroid carcinoma (PTC) from benign nodules and NIFTP. Methods: All thyroid FNAs from 2012 to 2016 of atypia of undetermined significance (A; n = 8) and suspicious for malignancy (S; n = 2) with sufficient cellularity and surgical follow-up, all FNAs preceding NIFTP (n = 6), and a random sample of PTC (n = 9) and benign (n = 10) cytology were studied. A modified Giemsa-stained slide from each case was scanned using the Aperio imaging system, and long (dl) and short (ds)-axis diameters were measured for 125 nuclei per case. Nuclear area and elongation were calculated. Results: Nuclear area was larger in PTC (mean, 77.2 μm2 [range, 70.6-86.0 μm2]) than benign (mean, 43.3 μm2 [range 38.2-52.2 μm2]) (P