Three-dimensional structure of the micro-blood vessels in thyroid tumors analyzed by immunohistochemistry coupled with image analysis

The structure of micro-blood vessels, one of the most important factors inf luencing the tumor growth and tumor metastasis among histological types of thyroid malignancy, was analyzed immunochemically by staining tissues for p latelet endothelial cell adhesion molecule-1 (PECAM-1). Human thyroid tumor tissue obtained at surgery, consisting of 18 cases of papillary carcinoma, 9 cases of follicular carcinoma, and 9 cases of anaplastic carcinoma were fixed in formalin solution, and paraffin sections were made. They were stai ned for PECAM-1 using the avidin-biotin complex (ABC) technique. The volume of the blood vessels and their three-dimensional (3D) structure were analy zed using an image analyzer. The volume ratios of blood vessels in thyroid tissues were: normal tissues, 1.10%; papillary carcinoma, 3.01%; follicular carcinoma, 8.13%; and anaplastic carcinoma, 0.91%. Ratios in malignant tum ors were larger than in normal tissues, except for anaplastic carcinoma. Th e typical 3D structure of micro-blood vessels was histopathologically varie d: branching tree-like blood vessels in papillary carcinomas; vessels of va ried diameter surrounding follicle structure in follicular carcinomas; and simple and immature vessels in anaplastic carcinomas. The volume and 3D str ucture of micro-blood vessels in thyroid malignant tumors differed from tho se in normal tissues, and varied according to histological classification.