In 2010 [5], WHO classified mucinous neoplasms in the following three categories with various differentiating features based on the extent of invasion, presence of extracellular mucin, presence or absence of PMP, and survival rate: mucinous adenoma, low-grade appendiceal neoplasm, and mucinous adenocarcinoma. The gene discussed is MUC5AC; the disease is mucinous cystadenoma.