Histopathology of parathyroid carcinoma. The tumor showed increased mitotic activity as well as a focus of angioinvasion (arrows) characterized by intravascular tumor cells admixed with thrombus (A). Green circles highlight mitotic figures in this photomicrograph (A). The tumor showed global loss of parafibromin expression, while the endothelial cells remained positive (B). The tumor cells were also variably positive for PGP9.5 (C) and galectin 3 (D), and showed reduced expression for p27 (E). While the tumor displayed intratumoral proliferative heterogeneity, the MIB 1 labeling index was as high as 25.45% in hot spots (F).