We describe the CT appearances of a fairly commonly encountered "special variant" carcinoma of the uterine corpus called uterine papillary serous carcinoma ( UPSC ). UPSC closely resembles ovarian papillary serous carcinoma microscopically but CT with contrast can differentiate between these two entities. In addition CT in this patient clearly showed the characteristic spread mode of this particularly aggressive form of endometrial carcinoma. Because UPSC has a significantly higher relapse rate than other histologic types of endometrial carcinoma it is important to recognize it at the time of the CT staging procedure. The spread pattern of UPSC suggests the need for adjuvant irradiation or chemotherapy.