A case of rectal carcinoid, 7 mm in diameter, with skip metastasis to the lateral lymph node.

The present case study presented a 59-year-old man with a 7 mm submucosal tumor in the lower rectum and swelling in a 7 mm lateral lymph node (the obturator lymph node). No swelling of the lymph nodes within the mesorectum was observed. The patient underwent laparoscopic intersphincteric resection with left side lateral lymphadenectomy. At the pathological examination, the patient was diagnosed with a rectal neuroendocrine tumor (Grade 1; carcinoid), which had invaded the perirectal tissues and exhibited lateral lymph node metastasis; however, mesorectal lymph node metastasis was not observed, therefore, the definitive diagnosis was rectal carcinoid with skip metastasis to the lateral lymph node. No sign of recurrence was observed at the 3 year follow-up. The treatment algorithm of rectal carcinoid was decided by the risk of lymph node metastasis. The present study confirmed skip metastasis to the lateral lymph node from the rectal carcinoid, which is typically very slow growing and has a low grade malignant potential.