“…However, reports of the radiologic features of retroperitoneal ancient schwannomas are very sparse. Loke et al [9] and Giglio et al [10] reported cases of retroperitoneal ancient schwannoma, including ultrasound and CT features, and noted that the tumors appeared as a well-defined complex cystic mass on ultrasonographic images but presented as a well-circumscribed complex cystic mass with or without septations on CT images. Nakano et al [11] reported on 11 cases of retroperitoneal ancient schwannoma and described ultrasonographic, CT and MRI features that were not different from those of ordinary retroperitoneal schwannomas, although internal heterogeneity was more frequently observed in the ancient retroperitoneal schwannoma cases.…”