Imaging findings of uterine adenosarcoma with sarcomatous overgrowth: two case reports, emphasizing restricted diffusion on diffusion weighted imaging

BACKGROUND: Adenosarcoma is classified as a mixed epithelial and mesenchymal tumor composed of a benign epithelial component and a malignant stromal component. The stromal component in adenosarcoma is usually low grade, and consequently the prognosis is relatively favorable. While, adenosarcoma with sarcomatous overgrowth (SO) is defined as an adenosarcoma in which the sarcomatous component constitutes more than 25% of the tumor. The stromal component is also high-grade sarcoma showing greater nuclear pleomorphism and mitotic activity, thus, it is associated with worse prognosis. MRI findings of adenosarcoma without SO have been described in previous literatures but the imaging findings in adenosarcoma with SO may be poorly defined. Therefore we present two cases of uterine adenosarcoma with SO. CASE PRESENTATION: Patient 1 was a 76-year-old woman referred to our hospital with complaint of abdominal distension and postmenopausal bleeding. Patient 2 was a 57-year-old woman with complaint of lower abdominal pain and abnormal uterine bleeding. On magnetic resonance imaging (MRI), T2 weighted imaging showed a large, heterogeneous high-intensity mass with hyperintense tiny cysts that expanded the uterine cavity and extended into the cervical canal for both patients. On diffusion-weighted imaging (DWI), both masses appeared as high signal intensity. Patient 2 also had a right ovarian adult granulosa cell tumor that may have contributed to development of the adenosarcoma. Patient 1 recurred with peritoneal sarcomatosis 6 months after surgery and died of the disease. Patient 2 also recurred with a left upper lung metastasis 3 months after surgery. CONCLUSIONS: DWI may depict pathological changes produced by SO of adenosarcoma as high signal intensity, even though SO does not seem to change MRI findings of adenosarcoma on other sequences. Therefore, DWI could potentially predict SO in presumptive adenosarcoma on MRI and the patient’s prognosis. It is also important for pathologists to know if SO can arise in adenosarcoma because they need to examine the tumor thoroughly to determine the percentage of SO component in the tumor volume when SO is present.