Autoimmune encephalitis after surgery for appendiceal cancer: A case report

BACKGROUND: Primary cancer of the appendix is rare and often difficult to diagnose preoperatively due to the lack of specific clinical symptoms. Autoimmune encephalitis (AIE) is the most common cause of non-infectious encephalitis. The etiologies of AIE include tumors (paraneoplastic), infections (parainfections), or recessive infections. The tumors that have been reported to cause AIE include thymomas, ovarian teratomas, lung cancers, and breast cancers. However, there are no reports of AIE occurring after surgery for appendiceal cancer. This report describes the diagnosis and treatment of a patient with an appendiceal cancer and postoperative AIE. CASE SUMMARY: We report the case of a 47-year-old man who was transferred to our hospital due to a recurrent low intestinal obstruction. Abdominal enhanced computed tomography was used to consider the possibility of a terminal ileal tumor with serous infiltration and lymph node metastasis. A right hemi-colectomy was performed under general anesthesia with an ileo-transcolon anastomosis and laparoscopic exploration. The postoperative pathologic evaluation revealed a high-grade goblet cell carcinoma of the appendix, accompanied by mesangial and abdominal lymph node metastases, and neural tube and vascular infiltration. The operation was completed without complication. The patient developed restlessness on postoperative day 4, and gradually developed a disturbance of consciousness on postoperative day 6. He was transferred to West China Hospital of Sichuan University and diagnosed with AIE. CONCLUSION: Albeit rare, the occurrence of neurologic and psychiatric symptoms in patients with an appendiceal cancer postoperatively suggests the possibility of AIE.