PAX-8 Is a Sensitive Marker for Thyroid Differentiation. Comparison with PAX-2, TTF-1, and Thyroglobulin
N Liles, G Hamilton, SS Shen, B Krishnan, LD Truong. The Methodist Hospital, Houston, TX; Baylor College of Medicine, Houston, TX
Background: Diagnostic markers for thyroid differentiation remain in development. PAX-8 and PAX-2 are members of a transcription factor family instrumental for fetal development and probably neoplastic transformation of kidney, Müllerian organs, and thyroid. Expression of PAX-8 and PAX-2 in thyroid tissue is evaluated and compared with that of thyroglobulin and TTF-1, the two traditional thyroid markers.
Design: Consecutive tissue sections of non-neoplastic thyroid tissue (n= 40), adenomatous nodule (n= 26), follicular neoplasms (n=10), papillary carcinoma (n=10), medullary carcinoma (n=4), and benign parathyroid tissue (n=6) were submitted for PAX-8, PAX-2, TTF-1, and thyroglobulin immunostain.
Results: PAX-8: 86/86 thyroid tissue samples regardless of diagnoses was stained (nuclear, 3/3+, in virtually 100% of tumor or non-neoplastic cells); 0/4 medullary carcinomas; 6/6 parathyroid (nuclear, 1-2/3+; about 30% of parenchymal cells). PAX-2: No staining for any thyroid, parathyroid, or medullary carcinoma specimens. TTF-1: 86/86 thyroid tissue samples regardless of diagnoses (nuclear, 3/3+, in virtually 100% tumor or non-neoplatic cells); 2/4 medullary carcinomas (nuclear, 1-2/3 +; about 20% of tumor cells); 0/6 parathyroid. Thyroglobulin: 86/86 thyroid tissue samples regardless of diagnoses (colloid and cytoplasm, 1-3/3+, in virtually 100% of tumor or non-neoplatic cells); 2/4 medullary carcinoma (cytoplasm, 3/3+, about 20% of tumor cells); 0/6 parathyroid; there was also staining for lymphoid cell cytoplasm and a constant heavy background.
Conclusions: 1) PAX-8 is a very sensitive marker for thyroid differentiation regardless of diagnoses. 2) In spite of ontogenic similarity with PAX-8, PAX-2 is not expressed by thyroid tissue; 3) PAX-8 is as sensitive for thyroid differentiation as TTF-1; however, there is overlapping staining patterns of PAX-8 and TTF-1 in parathyroid tissue and medullary carcinoma, suggesting a complementary diagnostic role between them; 4) PAX-8 is a better marker than thyroglobulin for detecting thyroid differentiation.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 39, Tuesday Afternoon