Stage II includes: IIA: T3, N0, M0; IIB: T4a, N0, M0; IIC: T4b, N0, M0. T3: Tumor invades through the muscularis propria into the subserosa or the mesoappendix. T4a: Tumor invades through the visceral peritoneum, including the acellular mucin or mucinous epithelium involving the serosa of the appendix or serosa of the mesoappendix. T4b: Tumor directly invades or adheres to adjacent organs or structures. N0: No regional lymph node metastasis. M0: No distant metastasis. (AJCC 8th ed.) [from NCI]