Symptomatic Subependymoma: Report of Four New Cases Studied with Computed Tomography and Review of the Literature

Abstract

The authors describe four cases of subependymoma studied with computed tomography (CT) and review 18 previously reported cases in an attempt to define the most characteristic CT presentation of this rare, benign tumor. Subependymoma usually appears as an isodense, or even hypodense, intraventricular tumor on plain CT scan and shows minimal or no enhancement in postcontrast studies. Differential diagnosis between subependymoma and the more malignant true ependymoma is difficult, particularly when the tumor occurs in the posterior fossa. Recognition of subependymoma should prompt the surgeon to attempt radical tumor removal because it can be achieved without sacrificing contiguous tissue and carries a good prognosis.

Simultaneous subependymomas in monozygotic female twins: further evidence for a common genetic or developmental disorder background

“…7 Subtle calcifications were demonstrated in our Case 1, consistent with the occurrence of tumor calcifications in 32%-59% of subependymoma cases. 11,14 As reported by others, there was no contrast enhancement in the subependymomas described here. According to the literature, cranial CT enhancement characteristics of subependymoma are variable, ranging from absent to little enhancement.…”

“…The tumor mass is hypoto isointense on T1-weighted images and hyperintense on T2-weighted images. 10,14,15 In our cases, the tumor masses were homogeneous. Conversely, other authors have reported a heterogeneous signal, which may be attributable to necrosis, calcifications, microcystic or cystic components, and hemorrhages.…”

“…Hyperattenuation compared with normal brain parenchyma, calcifications, cyst formation, and contrast agent enhancement are more commonly noted in ependymomas than in subependymomas. 6,13,14 Clarenbach et al in 1979 performed subtotal resections of subependymomas of the fourth ventricle followed by insertion of an atrioventricular shunt in 2 male siblings, 4 in contrast to our patients who underwent grosstotal resection without any further treatment. Gross-total resection is currently possible thanks to optimized microsurgical techniques and electrophysiological monitoring.…”

“…According to the literature, cranial CT enhancement characteristics of subependymoma are variable, ranging from absent to little enhancement. 10,14,15 Distinguishing subependymomas from ependymomas based on imaging findings is difficult, even though some features appear to be more characteristic for sub- ependymomas than for ependymomas. Subependymomas tend to grow in an intraventricular manner at the base of the fourth ventricle, whereas ependymomas tend to appear at the roof of the fourth ventricle and grow into the paraventricular space.…”

Clinical features and management of intracranial subependymomas in children

“…The distinctions between these tumours are even less apparent when they arise in the fourth ventricle in children. 20 The lack of vasogenic oedema in subependymoma may be a distinguishing feature from the otherwise similar ependymoma. 9 Choroid plexus papillomas most commonly occur in young patients and are intensely enhanced after contrast administration.…”