Bilateral internal auditory canal gangliogliomas mimicking neurofibromatosis Type II

Bilateral Internal Auditory Canal Metastasis From Lung Cancer on FDG PET/CT

ABSTRACT

The occurrence of metastatic tumor in the internal auditory canal is very rare. Thus, we report FDG PET/CT findings of bilateral Internal auditory canal metastasis from lung cancer in a 67-year-old man. FDG PET/CT and MRI showed nodules in the bilateral internal auditory canal with an SUVmax of 5.2. This case hints us that bilateral metastasis should be considered as differential diagnosis when we encounter bilateral nodule in the internal auditory.

Vestibular seizures and spontaneous downbeat nystagmus of ganglioglioma origin: a case report

BACKGROUND

Low-grade gangliogliomas (GGs) are typically epileptogenic intracranial neoplasms. Yet, the presentation of simplex vertiginous experience and spontaneous downbeat nystagmus (DBN) has not been reported to date.

CASE PRESENTATION

We present the case of a 26-year-old male with focal onset impaired awareness seizures, characterized by vertigo due to right temporal lobe epilepsy caused by ganglioglioma. As rare presentations, a spontaneous, consistent DBN in the absence of vertiginous experience was noticed. MRI suggested lesion in the right temporal pole. Twenty-four-hour continuous electroencephalogram (EEG) monitoring recorded periodic sharp and slow waves, originating from the right temporal lobe. The patient was completely relieved of the symptoms after surgical removal of the tumor, which was histologically confirmed as Grade I Ganglioglioma.

CONCLUSIONS

Asides from the cortical pathogenesis of epileptic vertigo, this case also provides insight into the DBN secondary to tumor of the temporal lobe. Moreover, the 24-h EEG is advantageous to recognize vestibular seizures and localize the ictal onset areas.

Malignant Peripheral Nerve Sheath Tumors are not a Feature of Neurofibromatosis Type 2 in the Unirradiated Patient

BACKGROUND

The published literature suggests that malignant peripheral nerve sheath tumors (MPNST) occur at increased frequency in neurofibromatosis type 2 (NF2). A recent review based on incidence data in North America showed that 1 per 1000 cerebellopontine angle nerve sheath tumors were malignant.

OBJECTIVE

To determine whether MPNST occurred spontaneously in NF2 by reviewing our NF2 database.

METHODS

The prospective database consists of 1253 patients with NF2. One thousand and nine are known to be alive at last follow-up. The presence and laterality/pathology of vestibular schwannoma at diagnosis and last follow-up was sought.

RESULTS

There were no cases of spontaneous MPNST with 2114 proven (n = 1150) and presumed benign (n = 964) vestibular schwannomas found. Two patients had developed MPNST (1 presumed) after having previously undergone stereotactic radiosurgery for a vestibular schwannoma.

CONCLUSION

In this series, and from the literature, malignant transformation of a vestibular schwannoma was not a feature of NF2 in the unirradiated patient. NF2 patients should not be told that they have an increased risk of malignant change in a vestibular schwannoma unless they undergo radiation treatment. However, very much larger datasets are required before it can be determined whether there is any association between NF2 and MPNST in the unirradiated patient.