Can CD10 be used as a diagnostic marker in thyroid pathology?

CD10-common acute lymphoblastic leukemia antigen is a membrane-bound zinc metalloproteinase that is expressed by different hematopoietic cell types at unique stages of lymphoid and myeloid differentiation. It was reported to be expressed in various nonlymphoid cells and tissue, as well as in various types of neoplasms. Recently, it has been found to be useful in the differential diagnosis of benign and malignant follicular-patterned lesions of the thyroid. In the present study, we evaluated the staining pattern of CD10 in various thyroid lesions, including 14 benign and 61 malignant cases, as well as in adjacent thyroid tissue. CD10 was negative in normal thyroid tissue, adenomatous nodules, minimally invasive follicular carcinoma, and well-differentiated carcinoma. It was expressed in nine of 14 (64.2%) conventional papillary carcinomas, four of 24 (16.6%) follicular variant of papillary carcinomas, three of six (50%) papillary microcarcinomas, one of nine (11.1%) widely invasive follicular carcinomas, and three of ten (30%) follicular adenomas. In contrast to results of previous studies, CD10 is not useful in the classification of thyroid follicular lesions as benign or malignant, but it shows strong positivity in conventional papillary carcinoma.