CDX2 Expression in Some Variants of Papillary Thyroid Carcinoma

Abstract

To the Editor The publication of the article of Enriquez et al1 coincided with the final steps of our study on the expression of CDX2 in normal and neoplastic follicular-derived cells of the human thyroid gland. Enriquez et al1 evaluated CDX2 expression in 11 cases of columnar cell variant (CCV) of papillary thyroid carcinoma (PTC) and in thyroid tissue microarrays (TMAs) composed of normal tissue, 38 cases of benign lesions (Hashimoto disease, Graves disease, lymphocytic thyroiditis, multinodular goiter, and papillary hyperplasia), and 33 samples of neoplastic conditions (8 follicular carcinomas, 9 conventional PTC, 2 tall cell variants of PTC, 2 poorly differentiated carcinomas, 6 anaplastic carcinomas, 4 medullary carcinomas, 4 Hurthle cell adenomas, and 2 follicular adenomas). Enriquez et al1 identified CDX2 expression in 6 (55%) of the 11 cases of CCV of PTC, but not in any other benign or malignant thyroid lesions. They only found focal or diffuse CDX2 immunoreactivity in tumors with pure columnar cell morphologic features (6/9 cases) but not in 2 cases with only focal columnar cell/mixed features. They concluded that CDX2 is selectively expressed in CCV of PTC and can be used to distinguish it from other variants of PTC with overlapping morphologic features. We used a TMA composed of 10% formalin-fixed, paraffin-embedded thyroid tissue samples: 50 follicular adenomas, 75 PTCs (35 classic subtype, 27 follicular variant, 4 solid variant, 3 tall cell variant, 2 diffuse sclerosing variant, 4 cribriform morular variant [CMV; 2 sporadic and 2 associated with familial adenomatous polyposis]), 48 follicular carcinomas (34 minimally invasive, 14 widely invasive), 15 poorly differentiated carcinomas (6 insular variant, 9 noninsular), 13 undifferentiated (anaplastic) carcinomas, and 15 normal thyroid tissue. The TMA was built using a tissue arrayer device (Beecher Instruments, Sun Prairie, WI), including duplicate 1.6-mm cores of …