Lateral lymph node metastasis in a patient with T1 upper rectal cancer treated by lateral lymph node dissection: a case report and brief literature review

BACKGROUND: Lateral lymph node (LLN) metastasis may occur in patients with advanced rectal cancers of which the lower margins are located at or below the peritoneal reflection. However, LLN metastasis from a T1 rectal cancer is rare. Here, we report a case of LLN metastasis from a T1 upper rectal cancer that was successfully treated by sequential LLN dissection. CASE PRESENTATION: A 56-year-old man was referred to our hospital for the treatment of a T1 upper rectal cancer. We performed a laparoscopic low anterior resection. Histological examination showed a moderately differentiated adenocarcinoma with submucosal layer invasion; the invasion depth was classified as head invasion, without vessel or lymph duct invasion. Tumor budding was classified as grade 1. A total of six lymph nodes were harvested, and no lymph node metastases were detected. The postoperative course was uneventful. At 6 months after surgery, however, the serum carcinoembryonic antigen levels were elevated, and abdominal computed tomography (CT) revealed swollen lymph nodes in the right internal and common iliac artery area. Positron emission tomography with CT revealed hot spots in the same lesions. A retrospective re-evaluation of the preoperative CT images revealed no apparent swollen lymph nodes; however, an unusual soft tissue area was detected around the right internal iliac artery. A right LLN dissection was performed. Fifteen lymph nodes were resected, and histologically, metastases of adenocarcinoma were identified in 3 nodes. The postoperative course was again uneventful. The patient was given 12 cycles of adjuvant chemotherapy with FOLFOX (fluorouracil, leucovorin, and oxaliplatin). The patient remains healthy and with no signs of recurrence at 30 months after the second surgery. CONCLUSIONS: LLN metastasis occurs very rarely in patients with T1 upper rectal cancer and no risk factors for lymph node metastasis; however, a careful perioperative examination of the LLN should be performed. In cases involving LLN metastasis, a LLN dissection may be a therapeutic option if performed with curative intent.