A Case of Lateral Lymph Node Metastasis from a Rectal Neuroendocrine Tumor Detected by Somatostatin Receptor Scintigraphy

Abstract

A 36-year-old man was found to have a submucosal tumor 15 mm in size in the lower rectum by colonoscopy performed for blood in stool, and was diagnosed as NET G1 by biopsy. Abdominal enhanced CT revealed swelling of the left closed lymph node, but it was calcified by CT, and SUVmax was less than 2 on PET-CT, and diffusion restriction was not observed on MRI. So, we performed robot-assisted abdominoperineal rectal resection (D3LD0). The pathological diagnosis was NET G2, pStage ⅢB, and he was treated by adjuvant chemotherapy with capecitabine. Seven months after surgery, CT revealed an increase in the left closed lymph node. Somatostatin receptor scintigraphy revealed abnormal accumulation in the left closed lymph node, and it was diagnosed as metastasis and was resected. The pathological diagnosis was NET metastasis. Twelve cases of lateral lymph node metastasis of NET have been reported, all of which were diagnosed by CT, PET and MRI. We report a case in which somatostatin receptor scintigraphy was useful for diagnosing metastasis.