Pathological examination of tissue from excisional biopsy of an inguinal lymph node revealed mucinous adenocarcinoma (Fig. 1b) with immunohistochemistry (IHC) positive for cytokeratin (CK) 7, CK20 and GATA3, and negative for CK5/6, CDX2 and p63. The gene discussed is CDX2; the disease is colon mucinous adenocarcinoma.