Uterine serous carcinoma arising in adenomyosis: a case report

Endometrial cancer arising in adenomyosis (EC-AIA), i.e., malignant transformation of the endometrium within adenomyotic foci, is a very unusual condition. We report a postmenopausal woman who had an unexpected diagnosis of uterine serous carcinoma (USC) arising from adenomyosis. A 55-year-old woman complained of anorexia with weight loss and mild abdominal pain. Pelvic cystic masses were shown by computed tomography (CT). CA125 in serum was 44.86 u/ml. Ultrasound detected a 50 × 36 mm subserous cystic-solid mass. It was misdiagnosed as a subserous uterine fibroid with cystic degeneration. The postoperative histopathological diagnosis was USC. This is the first time to discuss the ultrasound diagnosis of EC-AIA. The de novo cystic area in adenomyosis in postmenopausal women may indicate malignant transformation. Ultrasound is the first imaging choice for gynecological masses. Presenting the ultrasound image and identifying the factors that may contribute to misdiagnosis can help raise the examiner's attention to this condition and inform the diagnostic workup in the future.