Background: The objective of this article is to define the imaging characteristics of ancient schwannoma, which is a rare variant of benign schwannoma with degenerative changes, arising in the female pelvis simulating ovarian tumors.
Methods: Eleven surgically proven ancient schwannomas of the female pelvis were evaluated retrospectively on the basis of CT and MR findings.
Results: Typical intra-pelvic schwannoma was a neurologically asymptomatic large mass, which may situate at presacral or lateral pelvic region with the continuity to the nerve or neural foramen. Ancient schwannomas manifested as encapsulated solid masses with random or eccentric cystic areas, or as cystic masses with marginal crescent-shaped or nodular solid components. Hemorrhagic changes and calcifications were often observed on MRI and CT respectively. To detect ipsilateral normal ovary and to demonstrate centripetal displacement of the adjacent rectum or iliac vessels were helpful to diagnose the tumor as an extra-ovarian mass situated at the extraperitoneal region.
Conclusions: Diagnosis of ancient schwannoma before surgical treatment is important and should be made by its characteristic clinical and imaging findings.