We cannot prove that intraglandular tumor spread (neoplastic cell aggregates separated from the principal tumor mass by at least one layer of non-neoplastic thyroid) is the result of tumor cell growth inside blood or lymphatic vessels, since endothelial marker immunohistochemistry (CD31 and CD34) does not show reactivity around the neoplastic cell aggregates [13]. This evidence concerns the gene PECAM1 and neoplasm.