Subependymoma revisited: Clinicopathological evaluation of 83 cases

Object: Subependymomas are rare ependymal neoplasms. To date, a large clinicopathologic study of these benign neoplasms treated with modern neurosurgical techniques has not been reported. Methods: Eighty-three cases of subependymoma were retrieved from the files of the Armed Forces Institute of Pathology. Clinicopathological features were reviewed; chromogenic in situ hybridization analysis for chromosome 22 was performed (n = 8), and patient follow-up was obtained (n = 34). Overall, the patients included 68 males and 15 females, 1.5 to 85 years of age (mean, 51.0 years). Twenty-seven cases were discovered at autopsy and the remaining were surgical specimens (n = 56). Tumors arose in the posterior fossa (n = 43), lateral ventricles (n = 37), spinal cord (2) and only one arose in the temporal horn. Tumors ranged in size from 2.0 mm to 60 mm in greatest dimension (mean, 23.0 mm). Eighteen-percent (15/83) of subependymomas exhibited a mixed histologic pattern; that is, subependymoma together with another glial tumor. The most common mixture (13/15) was subependymoma and ependymoma. Surgical excision was used in all symptomatic patients; 10 patients received radiation. Four patients developed a recurrence due to incomplete excision. All patients were without evidence of disease at the last follow-up: alive (n = 28) or dead (n = 8). Conclusions: Age is the only variable found to be significantly associated with survival. Currently, surgical methods result in an excellent long-term clinical outcome. Subependymomas do not appear to be associated with NF2 mutations.