Introduction: Schwannoma in the lateral lymph node region is extremely rare; however, this tumor has been reported to have relatively high SUV on PET-CT, suggestive of malignancy.
Case: A 67-year-old man with advanced lower rectal cancer had a small nodule with FDG accumulation (SUVmax 2.6) near the left internal iliac artery. His preoperative diagnosis was rectal cancer with lateral lymph node metastasis. He underwent super-low anterior resection with lateral lymph node dissection. Histopathological examination was conclusive for pT3 (A), with an Rt263D lymph node metastasis. Interestingly, a schwannoma was detected among the harvested lymph nodes.
Conclusion: Although rectal cancer is known to involve pelvic lymph nodes, the role of preoperative diagnosis with FDG-PET is unclear. We should consider that schwannoma is associated with slight elevation of SUVmax and it may mimic lymph node metastasis.