MUC5AC and neoplasm: Necrotic LCCA usually originates from tumor necrosis at the center, resulting in cavities filled with fluid or necrotic tissue; mucinous LCCA is characterized by the secretion of abundant mucin by the tumor, leading to cystic changes, and is commonly seen in adenocarcinoma; inflammatory LCCA is associated with severe inflammatory reactions caused by the tumor, resulting in tissue destruction and the formation of cystic structures.