Monoclonal Antibody Hbme-1 Usefulness in Differentiation of Benign Neoplasm and Differentiated Thyroid Carcinoma

HBME-l is an antimesothelial monoclonal antibody that recognizes an unknown antigen on microvilli of mesothelial cells. The antibody is only relatively specific for mesothelium and is used in the differential diagnosis of mesothelioma and adenocarcinoma within the context of an appropriate immuno-histochemical panel. HBME-l has also been reported to strongly and uniformly stain papillary and follicular carcinoma of the thyroid while benign disorders have been usually negative. We studied the immunoreactivity of HBME-l in 90 cases of benign and malignant thyroid lesions. We found strong positive staining in the majority of papillary carcinomas (28/31), in some of follicular carcinomas (4/6), and in a few follicular adenomas (2/17). Negative staining was found in oxyphilic cell adenoma (0/4), nodular goiter (0/13) and undifferentiated carcinoma. The results suggest that monoclonal antibody HBME-l is useful in differentiating papillary and follicular carcinoma of the thyroid from benign lesions, especially in more differentiated lesions. Strong and generalized immunoreactivity for HBME-l in a follicular lesion should raise the suspicion of malignancy, but negative staining specially in poorly differentiated lesion does not rule out malignancy. Acta Medica Iranica, 43(2): 85-88; 2005