The definition of minimal extrathyroid extension in thyroid pathology by analyzing sizable intra- and extrathyroid blood vessels

Abstract

Background: To define the exact boundary of the intra- and extrathyroid aspects of the gland when determining the extent of cancer invasion, we plan to clarify the definition of sizable vascular structures, one of the helpful histologic clues in determining minimal extrathyroid extension (ETE). We hypothesized that arterial wall thicknesses in extrathyroid soft tissue would be significantly different from arteries in the thyroid parenchyma.Materials and methods: Twenty cases of papillary carcinoma were selected. The numbers and wall thicknesses of the arteries and arterioles in intra- and extrathyroid tissue were evaluated. The absence of nerve tissue in the thyroid gland was confirmed by the S-100 protein immunohistochemical stain.Result: The comparison of the mean thicknesses (μm) of the total arteries between extrathyroid and intrathyroid tissues in the retrospective study (26.88 vs. 15.07) and the prospective study(35.24 vs. 16.52) revealed significant differences (p=0.000). The greatest thickness of intrathyroidal arteries was 67.93 μm. Conclusion: With a result, the study showed that the extrathyroidal arteries were significantly thicker than intrathyroidal arteries. We suggest that the sizable blood vessel of extrathyroidal arteries should be greater than 67.93 μm in thickness.