Cytological detection of papillary thyroid carcinomas by nuclear membrane decoration with emerin staining

Decoration of the nuclear membrane by emerin staining enhances detection of nuclear irregularities typical of papillary thyroid carcinoma (PTC). Our study aims to verify whether staining with emerin is a helpful diagnostic marker in fine-needle aspiration (FNA) cytology. We first designed a prospective study on smears, Thin Prep, and cell block specimens to prove the feasibility of the procedure; subsequently, we designed a retrospective study of 78 FNA cell blocks from cases that, after surgery, turned out to be either benign (34 cases) or malignant lesions (44, of which 31 PTC). From each sample, we obtained two slides, one stained with hematoxylin and eosin (H&E) and the other with emerin. In cases classified as Thy3, HBME-1 and galectin 3 (Gal3) stains had also been performed. Two blinded observers made the judgment concerning Thy categories (as proposed by the British Thyroid Association), first on H&E, then on emerin, HBME-1, and Gal3 stained slides. On cytological preparation, emerin staining represents an effective tool for the detection of nuclear irregularities, allowing for the identification of cases of PTC. In Thy3 cases, emerin staining's sensitivity and specificity (64% and 96%) proved higher than HBME-1's (60% and 88%) and Gal3's (61% and 68%). In conclusion, the immunohistochemical definition of the nuclear membrane, as determined by emerin stain, is a useful tool in the cytological diagnosis of thyroid lesions and can help to solve inconclusive cases by highlighting nuclear irregularities typical of PTC.