Role of EUS and EUS-guided FNA in the diagnosis of rectal implantation cyst at an anastomosis site after a previous low anterior resection for a rectal cancer without evidence of cancer recurrence.

Background: Rectal implantation cysts occurring at an anastomosis site after a low anterior resection for rectal cancer need to be distinguished from locally recurrent rectal cancer.

Objective: Our purpose was to evaluate the role of EUS and EUS-FNA in the diagnosis of rectal implantation cyst.

Design: Case series.

Patients: A review of medical records identified 3 men and 1 woman who were diagnosed with rectal implantation cyst by EUS and EUS-FNA.

Results: All 4 cases had undergone a low anterior resection with the double-stapling technique for a rectal cancer from 12 to 67 months (median 33.8 months) earlier. Follow-up colonoscopy revealed a rectal submucosal tumor at an anastomosis site. EUS revealed cystic lesions with heterogeneous wall thickness from the third layer or the fourth layer to the surroundings. EUS-FNA revealed mucin that contained a few inflammatory cells and no malignant cells in any of the patients. From the findings of EUS and EUS-FNA, all patients were diagnosed with rectal implantation cyst, thus avoiding surgery.

Limitation: Small number of patients.

Conclusions: EUS and EUS-FNA are useful in the diagnosis of rectal implantation cyst and the avoidance of unnecessary radical surgery.