Abdominoperineal Resection for Unexpected Distal Intramural Spreading of Rectal Cancer

INTRODUCTION: In rectal cancer, distal intramural spread may sometimes occur, but a maximum extent of distal spread of > 6 cm is very rare. CASE PRESENTATION: A 65-year-old Japanese male with an advanced rectal cancer tumor with para-aortic lymph node metastasis was admitted. We performed a low anterior resection with lymphadenectomy, but the intraoperative frozen-section analysis of margins revealed malignant cell positivity; we, therefore, performed an abdominoperineal resection. Pathological findings showed that the maximum extent of distal spread was 6 cm. After 12 courses of FOLFOX4 as adjuvant chemotherapy, abdominal computed tomography revealed whole lymph node metastases, including Virchow's node. Though FOLFIRI + panitumumab was started, he was not eligible for additional chemotherapy after 10 cycles. CONCLUSION: An intraoperative frozen pathology examination was helpful for the additional resection, when unexpected distal spreading had occurred in rectal cancer. The evidence of a distal negative margin should not be underestimated.