Delayed abdominal wall abscess after abdomino-perineal resection simulating local recurrence of rectal cancer

INTRODUCTION We report a rare case of delayed abdominal wall abscess after abdominoperineal resection (APR) for rectal cancer. CASE DESCRIPTION A 63-year-old woman was diagnosed with rectal cancer and received chemo-radiotherapy, followed by APR. One year after surgery, the patient complained of pain and skin redness in the lower abdomen. A low-density mass lesion with 5.9-cm diameter was found in the lower abdominal wall by computed tomography, which showed high uptake on positron-emission tomography. These findings suggested the possibilities of either delayed abscess formation or abdominal wall recurrence of rectal cancer with central necrosis. Percutaneous drainage was performed. The content was a purulent exudate, without neoplastic cells in the cytology. The lesion quickly disappeared after the drainage, and no recurrence of the tumor was observed for more than 2 years. DISCUSSION AND EVALUATION In this case, the un-absorbable yarn, such as silk, has not been used during the operation, no foreign body was retained in the abdominal wall, and there was no associated inflammatory bowel disease. Use of neoadjuvant chemoradiotherapy was the only possible cause of delayed abscess formation in this case. CONCLUSION In case local recurrence is suspected by imaging modalities in the postoperative of colorectal cancer, especially those with precedent chemoradiotherapy or radiotherapy, although rare, the possibility of a delayed abscess formation should also be considered.