The pathologic characteristics of these appendix-localized mucinous tumors include cell atypia, loss of muscularis mucosae, submucosal fibrosis, “pushing invasion”, dissection of acellular mucin in the wall, sinous or flattened epithetlial growth, rupture of the appendix, or mucin, and/or cells outside the appendix. This evidence concerns the gene MUC5AC and mucinous neoplasm.