Low grade appendiceal mucinous neoplasm (LAMN) is a tumour of the appendix characterized by a mucinous epithelial proliferation. Grossly the appendix appears dilated, filled with mucin, and the wall thinned. Microscopically the architecture shows a filiform, villous, or undulating epithelium with tall cytoplasmic mucin vacuoles and compressed bland nuclei. Additional findings include a broad pushing margin, various degrees of extracellular mucin (with absent lymphoid tissue), fibrosis, hyalinization, and calcification of the appendiceal wall. The two most identified gene mutations in LAMNs are KRAS and GNAS.