SICC and lymph node metastasis clinically appeared within 3 months and 3 weeks, respectively. Suspected ICC that rapidly progresses should be considered SICC and treated with early resection. SICC is often missed in clinical diagnosis and has a poor prognosis, even after curative resection. While an alternative strategy involving preoperative biopsy and neoadjuvant therapy may be beneficial, it should be approached with discretion due to the potential risks of tumor progression and peritoneal dissemination.