Immunophenotyping demonstrated TTF-1 nuclear positivity in the metastatic tumor alongside a classic colorectal profile: cytokeratin 7 (CK7) negativity, cytokeratin 20 (CK20) positivity, strong caudal-type homeobox transcription factor 2 (CDX2) and special AT-rich sequence-binding protein 2 (SATB2) nuclear expression, and absence of Napsin A. The patient underwent surgical resection of the primary sigmoid colon tumor and received 16 cycles of capecitabine plus bevacizumab chemotherapy. The gene discussed is CDX2; the disease is sigmoid neoplasm.