Clinical History
A young adult man presented with headaches and dizziness, but otherwise healthy.
Imaging Findings
A 30 year old man presented to our MRI department because of chronic headaches and dizziness. MRI performed on a 1.5T scanner with a multichannel neurovascular array coil showed a midline mass in the 4th ventricle with hyperintense signal on T2- and iso- to slightly hypo-intense signal on T1-weighted images. The tumour was smoothly delineated against the brain parenchyma on T2 weighted images (Fig. 1) and showed a cauliflower-like border towards the ventricle lumen (Fig. 2). After intravenous gadolinium administration (0,1 mmol/kg) no intralesional enhancement was observed (Fig. 3). The patient was referred to a neurosurgery department, where the tumour was completely resected through a suboccipital midline craniotomy. The histopathological diagnosis was subependymoma WHO grade 1.
An MR follow-up study after six months showed no evidence of recurrence.
Discussion
Subependymomas are rare CNS tumours with a reported frequency of 0.51% among brain tumours treated operatively within 8 years at a large neurosurgical centre in the United States [1]. Age or sex predilection has not been observed. The 4th ventricle is a typical location, but other sites have also been reported, namely the lateral ventricles and the spinal cord [2]. In the ventricular system, they are usually found incidentally, either by imaging methods or at autopsy. They may become clinically apparent if symptoms of mass effect or occlusive hydrocephalus develop. Although subependymomas are usually benign [3], sudden death may result from acute obstruction of the CSF circulation. The imaging characteristics of this ependymal-cell-derived tumour are poorly defined, but little or no contrast enhancement seems to be a feature that could help to differentiate it from other non-invasive intraventricular masses. However, subependymomas appear to be mixed with other glial tumours, mostly ependymoma, in about 18%, which may explain the presence of contrast enhancement in some of the reported cases. Complete surgical removal usually results in an excellent long-term survival. Recurrences are encountered only in cases with incomplete excision [2].
Differential Diagnosis List
Subependymoma WHO grade I
Final Diagnosis
Subependymoma WHO grade I
