Imaging characteristics of 4th ventricle subependymoma

Abstract

Purpose: Subependymomas located within the 4th ventricle are rare, and the literature describing imaging characteristics is sparse. Here, we describe the clinical and radiological characteristics of 29 patients with 4th ventricle subependymoma.

Methods: This is a retrospective multi-center study performed after Institutional Review Board (IRB) approval. Patients diagnosed with suspected 4th ventricle subependymoma were identified. A review of clinical, radiology, and pathology reports along with magnetic resonance imaging (MRI) images was performed.

Results: Twenty-nine patients, including 6 females, were identified. Eighteen patients underwent surgery with histopathological confirmation of subependymoma. The median age at diagnosis was 52 years. Median tumor volume for the operative cohort was 9.87 cm³, while for the non-operative cohort, it was 0.96 cm³. Thirteen patients in the operative group exhibited symptoms at diagnosis. For the total cohort, the majority of subependymomas (n = 22) were isointense on T1, hyperintense (n = 22) on T2, and enhanced (n = 24). All tumors were located just below the body of the 4th ventricle, terminating near the level of the obex. Fourteen cases demonstrated extension of tumor into foramen of Magendie or Luschka.

Conclusion: To the best of our knowledge, this is the largest collection of 4th ventricular subependymomas with imaging findings reported to date. All patients in this cohort had tumors originating between the bottom of the body of the 4th ventricle and the obex. This uniform and specific site of origin aids with imaging diagnosis and may infer possible theories of origin.

Keywords: Fourth ventricle; Neuroimaging; Rare tumors; Subependymoma.

Fig. 1

A Sagittal T1 contrast enhanced image demonstrates the presence of a moderately enhancing 4th ventricular mass below the body of the ventricle and extending into the obex. B Sagittal T1 contrast enhanced image demonstrates a minimally enhancing mass (predominantly T1 isointense) again situated in the low fourth ventricle, below the body of the fourth ventricle and illustrating the spectrum of enhancement seen with subependymomas. C Axial T2 image of a typical mildly T2 hyperintense subependymoma at midline extending toward the foramen of Magendie. D Axial T2 image of a more T2 hyperintense subependymoma extending through the foramen of Luschka bilaterally

Fig. 2

Sagittal illustration demonstrating a subependymoma centered below the body of the 4^th ventricle and terminating near the level of the obex