A Case of Foreign Body Granuloma that Changed from PET/CT a Negative to False Positive after Colorectal Cancer Surgery

Abstract

We report a case of an 82-year-old woman who underwent sigmoid colectomy for sigmoid colon cancer in December 2013. Computed tomography (CT) was performed in December 2015 because carcinoembryonic antigen (CEA) levels showed a mild increase to 5.4 ng/ml ; however, no recurrence was found. Positron emission tomography (PET)/CT was performed in May 2016 at the patient's request and no abnormal accumulation was seen. In January 2018, CEA levels increased to 9.3 ng/ml ; therefore, CT was performed in February 2018, but there was no sign of recurrence. However, CEA levels increased further to 10.3 ng/ml and PET/CT was performed again. The PET/CT detected a small nodule with intense fluorodeoxyglucose uptake (maximum standardized uptake value 4.3) on the ventral side of the left common iliac artery and recurrence of peritoneal dissemination was suspected. As all CT images obtained after surgery for sigmoid colon cancer showed a small nodule with a major axis of approximately 9 mm in the same area, it was considered that the small nodule had changed from PET/CT negative to positive. Tumor removal was performed in April 2018 post-diagnosis and treatment. Histopathological examination of the resected specimens showed no malignant findings, and abscess and inflammatory granulation formed around the suture. Therefore, it was diagnosed as foreign body granuloma.