EPEN-07. PATTERNS OF EXTRANEURAL METASTASES IN PEDIATRIC SUPRATENTORIAL EPENDYMOMA: CASE SERIES AND REVIEW OF THE LITERATURE

BACKGROUND Ependymomas account for 10% of all malignant pediatric intracranial tumors. Standard therapy includes maximal safe surgical resection followed by involved-field radiation. Up to 50% of localized pediatric ependymomas recur. Extraneural metastases at time of recurrence are rarely reported. OBJECTIVE To describe extraneural metastases of pediatric ependymomas. METHODS Retrospective review of patients’ medical records and literature review. RESULTS Three patients with history of locally recurrent, supratentorial ependymoma developed extraneural metastases: one in a cervical lymph node, one with a scalp nodule, and one with a dural lesion. Each extraneural recurrence had similar histologic and molecular features as the initial diagnosis. The cervical lymph node recurrence was treated with multimodal therapy; she is without disease four years later. The isolated scalp nodule occurred at the exit site of a subgaleal drain placed during prior resection. Following nodule resection, he developed additional scalp and lymph node disease and is receiving palliative care. The isolated dural recurrence occurred at the exit site of a ventriculoperitoneal shunt placed following a previous resection. She died of progressive disease 18 months after dural lesion resection. Reports of lymph node, scalp, and dural metastases of ependymomas are exceedingly rare, and outcomes are poor. CONCLUSIONS Extraneural manifestations of ependymoma are rare. Regional seeding from prior surgical procedures may play a role in metastatic spread. Extraneural metastases should be considered in children previously treated for ependymoma who develop local findings even in the absence of CNS relapse. Salvage therapy with curative intent should be considered using a multimodal approach.

RADT-39. 68Ga- DOTATATE CT/PET FOR GAMMA KNIFE RADIOSURGERY PLANNING AND TARGET DELINEATION IN PATIENTS WITH MENINGIOMA

BACKGROUND Stereotactic radiosurgery (SRS) planning for patients with meningiomas can be confounded by difficulty in identifying the tumor boundary, especially in those who have had prior surgery. Recent data have suggested the benefit of 68Ga-DOTATATE CT/PET scans in delineation of meningioma compared to MRI alone. We propose that incorporating 68Ga-DOTATATE PET scans in addition to MRI in SRS planning will provide better target identification and tumor coverage compared to MRI alone. METHODS We reviewed patients with meningioma who had MRI and 68Ga-DOTATATE PET imaging over 12 months. Images were imported into Velocity treatment planning software and separated into two different sessions, one in which only the MRI was accessible, and a second which had the PET scan fused to the MRI. Three different users were asked to contour the residual meningioma as gross tumor volume (GTV) first with MRI alone, and then with the PET/MRI fusion. The volume of each GTV pre-and post-PET fusion was compared and a Dice index was generated. RESULTS Four patients with 6 GTV targets were identified. PET fusion identified new lesions close to the initial GTV targets in 2 patients. The first was a discontinuous dural lesion in the post-op bed. The second was a nodular dural lesion along the left high parietal convexity adjacent to a prior craniectomy and mesh duraplasty site. In the third patient, PET scan identified a greater extent of disease in the skull base. Across all observers, GTV volumes were significantly increased when PET fusion was used. The average volume (cc) increase was 111.6%±66.2%. The average Dice index was 0.58±0.17. CONCLUSION 68Ga-DOTATATE PET scan fused with MRI improved the visualization of meningiomas in patients undergoing SRS. A larger experience is needed to confirm this trend. We have begun to use DOTATATE-PET imaging regularly when imaging patients with meningiomas for SRS.

Extradural autologous temporal muscle graft mimicking a meningioma

Meningiomas are the most common dural tumour, but there are also many other dural masses which mimic their appearances, such as neoplastic and non-neoplastic lesions. In this paper we report another mass which may mimic a dural lesion, namely a muscle graft harvested from the temporal site and left in situ, used to achieve haemostasis in a posttraumatic temporal extradural hematoma in a young male patient. Solid knowledge of differentiating neuroimaging characteristics of dural masses, as well as its corroboration with the patient’s medical history are extremely helpful in establishing an accurate diagnostic.

Current insights in CSF leaks: a literature review of mechanisms, pathophysiology and treatment options

A cerebrospinal fluid (CSF) leak occurs when there appears a fistula between the dura and the skull base and it is usually characterized by discharge of cerebrospinal fluid from the nose. Cerebrospinal fluid leaks may have many etiologies, the most common being trauma. The most common site of dural lesion is the cribriform plate of the ethmoid. Diagnosis can be achieved by a multitude of techniques, high-resolution computed tomography being the modality of choice and it may be completed with magnetic resonance imaging or cisternography. Treatment may be either conservative, either surgical, related to the cause, the site and the duration of CSF leak. Conservative treatment usually includes strict bed rest, elevated bed head and no straining, nose blowing or stretching, with resolution of the majority of traumatic CSF leaks in seven days. Surgical treatment consists of a variety of approaches (intracranial/extracranial, open/endoscopic). The future trend is represented by minimally invasive endoscopic approaches, with a success rate of almost 90%; however, open transcranial or extracranial interventions still have indications in the surgical management. CSF leaks must be correctly diagnosed and treated, because the risk of intracranial complications increases 10-fold when the leakage persists.