CLINICAL ARTICLE J Neurosurg 122:49–60, 2015 Clinical, radiological, and pathological features in 43 cases of intracranial subependymoma Zhiyong Bi, MD, Xiaohui Ren, MD, Junting Zhang, MD, and Wang Jia, MD Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China ObjECT Intracranial subependymomas are rarely reported due to their extremely low incidence. Knowledge about sub- ependymomas is therefore poor. This study aimed to analyze the incidence and clinical, radiological, and pathological features of intracranial subependymomas. METHodS Approximately 60,000 intracranial tumors were surgically treated at Beijing Tiantan Hospital between 2003 and 2013. The authors identified all cases in which patients underwent resection of an intracranial tumor that was found to be pathological examination demonstrated to be subependymoma and analyzed the data from these cases. RESULTS Forty-three cases of pathologically confirmed, surgically treated intracranial subependymoma were identi- fied. Thus in this patient population, subependymomas accounted for approximately 0.07% of intracranial tumors (43 of an estimated 60,000). Radiologically, 79.1% (34/43) of intracranial subependymomas were misdiagnosed as other dis- eases. Pathologically, 34 were confirmed as pure subependymomas, 8 were mixed with ependymoma, and 1 was mixed with astrocytoma. Thirty-five patients were followed up for 3.0 to 120 months after surgery. Three of these patients expe- rienced tumor recurrence, and one died of tumor recurrence. Univariate analysis revealed that shorter progression-free survival (PFS) was significantly associated with poorly defined borders. The association between shorter PFS and age < 14 years was almost significant (p = 0.51), and this variable was also included in the multivariate analysis. However, multivariate analysis showed showed only poorly defined borders to be an independent prognostic factor for shorter PFS (RR 18.655, 95% CI 1.141–304.884, p = 0.040). In patients 14 years of age or older, the lesions tended to be pure subep- endymomas located in the unilateral supratentorial area, total removal tended to be easier, and PFS tended to be longer. In comparison, in younger patients subependymomas tended to be mixed tumors involving the bilateral infratentorial area, with a lower total removal rate and shorter PFS. CONCLUSIONS Intracranial subependymoma is a rare benign intracranial tumor with definite radiological features. Long-term survival can be expected, although poorly defined borders are an independent predictor of shorter PFS. All the features that differ between tumors in younger and older patients suggest that they might have different origins, bio- logical behaviors, and prognoses. http://thejns.org/doi/abs/10.3171/2014.9.JNS14155 KEY WORDS subependymoma; clinical features; radiology; pathology; survival; oncology NTRACRANIAL subependymoma is rare, representing istics of this type of tumor, reliable preoperative diagno- only 0.51% of all central nervous system tumors, and sis remains challenging, and many intracranial subepen- the clinical symptoms are associated with the tumor dymomas are misdiagnosed as other diseases.17 Ilocation.16 It has been proposed that subependymomas To learn more about the clinical, radiological, and derive from ependymal-glial precursor cells, astrocytes pathological features of intracranial subependymomas, of the subependymal plate, or a mixture of astrocytes we retrospectively reviewed and analyzed all of the cases and ependymal cells.12,13,16 Subependymoma was first de- surgically treated and pathologically confirmed as in- scribed by Scheinker in 1945, and more than 100 cases tracranial subependymomas in Beijing Tiantan Hospital have been described since this time.1,4,6–9,11,17,18 As a result from 2003 to 2013. We report the clinical, radiological, of the sparse reporting of subependymoma cases, their and pathological features of the entire series of cases of clinical, radiological, and pathological features remain subependymoma are reported and analyze the features as- unclear. Due to the rarity and variable imaging character- sociated with longer PFS and OS. ABBREVIATIONS CPA = cerebellopontine angle; OS = overall survival; PFS = progression-free survival; SGCA = subependymal giant cell astrocytoma; VP = ventriculoperitoneal. SUBMITTED January 19, 2014. ACCEPTED September 2, 2014. INCLUDE WHEN CITING Published online October 31, 2014; DOI: 10.3171/2014.9.JNS14155. DISCLOSURE The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. ©AANS, 2015 J Neurosurg Volume 122 • January 2015 49 Unauthenticated | Downloaded 10/04/21 07:35 AM UTC Z. Bi et al. Methods mately 60,000 cases of surgically intracranial tumors that Patient Population were treated in Beijing Tiantan Hospital during the study period. The frequency of intracranial subependymoma Review of the records of Beijing Tiantan Hospital for was thus approximately 0.07%. the period from 2003 to 2013 identified 43 patients who Clinical data are summarized in Tables 1 and 2. The had undergone resection of intracranial tumors that were age at onset of symptoms or signs in the 43 patients pathologically confirmed to be subependymomas. ranged from 2 to 68 years; the mean age was 33.1 ± 18.9 years (all means are expressed ± SD). These patients in- Record of Clinical and Radiological Material cluded 22 males and 21 females. The time from onset of The clinical data and operation records of 43 cases symptoms or signs to admission ranged from 10 days to with subependymoma were retrospectively reviewed. The 20 years (median 2 months). The initial manifestations of recorded information included patient age, sex, initial the tumor were headache or intracranial hypertension in manifestation, duration of symptoms or signs, preopera- 29 patients, dizziness in 10, limb weakness in 5, epilepsy tive diagnosis, tumor size, location, CT and MRI features, in 4, memory loss in 4, ataxia in 2, tremor in 2, blurred vi- extent of resection, and surgical outcome. Tumor size was sion in 1, and an enlarged head in 1; in 3 cases, the tumors recorded according to the measurement of the maximum were incidental findings. diameter on MR images. The extent of resection was re- All 43 intracranial subependymomas were primary. In corded as gross total, subtotal, or partial according to the 34 cases (79.1%), the tumors were misdiagnosed preop- operation record and postoperative MR images. Hydro- eratively; 14 tumors (32.6%) were misdiagnosed as glio- cephalus was defined as abnormal accumulation of cere- mas, 9 (20.9%) as central neurocytomas, 8 (18.6%) with brospinal fluid in the ventricles. ependymomas, 1 (2.3%) as medulloblastoma, 1 (2.3%) as meningioma, and 1 (2.3%) as cavernous an gioma. Pathological Examination Nine patients received postoperative radiotherapy, and 1 patient received postoperative chemotherapy after tu- Fresh paraffin-embedded tumor tissue was cut into mor recurrence. 5-mm sections and stained with hematoxylin and eosin. Immunohistochemical staining was used for differential diagnoses. The microscopic pathologies of 43 cases were Radiological Features of Intracranial Subependymomas reviewed by 2 independent neuropathologists according The radiological data are summarized in Table 3. The to the WHO grading system.10 Immunohistochemical lesion was located near the Monro foramen in 21 cases, staining was assessed using a semiquantitative scoring in the fourth ventricle in 7 cases, in the occipital horn system. The expression levels were based on the percent- of the lateral ventricle in 6 cases, in both the region of age of immunopositive cells (negative, < 25% of tumor the Monro foramen and the 3rd ventricle in 3 cases, in cells; positive, ≥ 25% of tumor cells). the temporal horn of the lateral ventricle in 1 case, in the fourth ventricle and the pons in 1 case, in the CPA in 1 Long-Term Follow-Up case, in the frontal lobe in 1 case, in the parietal lobe in 1 case, and in the thalamus, midbrain, and temporal lobe Among 43 patients with subependymoma, 35 were in 1 case. followed up after surgery. Postoperative complications The tumor was located on the left side in 19 cases and and progression-free and overall survival were recorded. on the right side in 13 cases; it was bilateral in 11 cases. Progression of subependymoma was defined according to Multiple lesions were revealed in only 1 case, while the radiological findings after tumor removal. Progres- single lesions were observed in 42 cases. Regarding tumor sion-free survival (PFS) was defined as the time between shape, 39 tumors were spherical, and 4 were irregular. initial surgery and tumor progression on radiology. Over- The maximum diameters of the lesions ranged from all survival (OS) was defined as the time between initial 2.0 to 12.0 cm (mean 4.4 ± 1.7 cm). surgery and death. CT images were available in 22 cases. The tumors presented as a hypodensity without calcification in 13 of Statistical Analysis these cases, a hypodensity with calcification in 2 cases, an To select parameters associated with longer PFS and isodensity without calcification in 4 cases, an isodensity OS, the log-rank test and Cox regression model were used. with calcification in 1 cases, and a hyperdensity without The chi-square test was used for the comparison of adult calcification in 2 cases. and childhood subependymomas. The statistical software MR images were available in 38 cases. The tumors SPSS 13.0 (SPSS for Windows,