Extrauterine Endometrial Stromal Sarcoma Mimicking Colorectal Cancer With Metastases.

Extrauterine endometrial stromal sarcoma (EESS) is extremely rare, especially with the colorectum involvement. We describe 18 F-FDG PET/CT findings of EESS in the sigmoid colon and rectum in a 46-year-old woman who complained diarrhea. 18 F-FDG PET/CT revealed multiple hypermetabolic lesions in the abdomen and pelvis, including the sigmoid colon and rectum. Therefore, colorectal cancer with metastases was initially suspected; however, ultimately low-grade EESS was pathologically confirmed. Widespread EESS with intestine involvement revealed by 18 F-FDG PET/CT should be carefully distinguished from colorectal cancer with metastases.