Detection of High Mobility Group I HMGI(Y) Protein in the Diagnosis of Thyroid tumors: HMGI(Y) expression represents a potential diagnostic indicator of carcinoma.

we analyzed HMGI(Y) expression by a combination of immunohistochemistry and reverse transcription-PCR in 358 thyroid tissue samples that were representative of the spectrum of thyroid tumor pathology. HMGI(Y) was detectable in 18 of 19 follicular carcinomas, 92 of 96 papillary carcinomas, and 11 of 11 undifferentiated (anaplastic) carcinomas but in only 1 of 20 hyperplastic nodules, 44 of 200 follicular adenomas, and 0 of 12 normal tissue samples. The correlation between HMGI(Y) expression and a diagnosis of carcinoma was highly significant (P < 0.0001). We also prospectively collected and analyzed for HMGI(Y) expression by immunohistochemistry and reverse transcription-PCR in 12 fine needle aspiration biopsies from 10 patients who subsequently underwent surgical removal of a solitary thyroid nodule. HMGI(Y) was detectable only in the four fine needle aspiration biopsies, corresponding to the thyroid nodules that were definitively diagnosed as carcinomas after surgery (two follicular carcinomas and two papillary carcinomas). The remaining eight samples (six follicular adenomas and two samples consisting of normal follicular cells) were negative. The findings of this study confirm the differential expression of HMGI(Y) in thyroid neoplasia and indicate the HMGI(Y) protein as a potential marker for thyroid carcinoma.