Metastatic gingival tumor from rectal cancer diagnosed with CDX2.

Metastatic tumors of the oral region are very rare, accounting for approximately 1% of intraoral malignant tumors. Caudal-related homeobox transcription factor (CDX2) regulates the development and differentiation of intestinal epithelial cells. We report herein a case of metastatic gingival tumor from rectal cancer after low anterior resection in which immunohistochemical analysis of CDX2 was useful for diagnosis of the origin. To the best of our knowledge, our case is the first report that immunohistochemical staining with CDX2 can contribute to diagnose metastatic gingival tumor from rectal cancer.