AGN343 patient had a pseudomyxoma peritonei (CK7 − /CK20 score 3 + /CDX2 score 3/SABT2 score 1, and ER − /PAX8 − /WT1 −); she underwent right and transversal colectomy during debulking, but neither primary cancers nor polyps were identified. The gene discussed is CDX2; the disease is cancer.