Liver metastasis from rectal neuroendocrine neoplasm detected 15 years after primary resection

BACKGROUND: Rectal neuroendocrine neoplasms can induce liver metastasis. However, few reports exist on the associated long-term recurrence rates. We report a case of liver metastasis identified 15 years after rectal neuroendocrine neoplasm resection. CASE PRESENTATION: A 50-year-old woman was on semi-annual follow-up after undergoing mastectomy for breast cancer (pT1N0M0) and low anterior resection for grade 1 rectal neuroendocrine neoplasm (pT1b, ly1, v1). Fifteen years postoperatively, a 7-mm hyperechoic mass was identified at liver segment 6. Magnetic resonance imaging revealed a slight growth of the mass. Positron emission tomography/computed tomography revealed radiotracer accumulation in the lesion. Laparoscopic hepatectomy was performed. The histopathological diagnosis was grade 2 neuroendocrine neoplasm. The pathological findings and clinical course indicated the tumor originated in the rectum. CONCLUSIONS: Our findings highlight the need to reassess the optimal postoperative follow-up period for patients with rectal neuroendocrine neoplasm.