Histology confirmed a poorly differentiated appendiceal mucinous adenocarcinoma with signet ring cell, staged as pT3 N0 (0/12) with adherence to the uterus, right ovarium, and sigmoid colon but without direct invasion and obvious perforation or extraluminal mucin (Figure 4). The gene discussed is MUC5AC; the disease is colon mucinous adenocarcinoma.