Malignant peripheral nerve sheath tumour transformation of histological benign vestibular schwannoma after stereotactic radiosurgery in patients without neurofibromatosis.

Stereotactic radiosurgery (SRS) poses a minimal but important risk for tumour transformation, typically occurring 8-10 years after the treatment. Malignant peripheral nerve sheath tumour (MPNST) is the most common tumour arising from a vestibular schwannoma treated with SRS, with only 14 cases previously reported. We present the fifteenth case and describe its evolution and clinical course. A 56-year-old man without a history of neurofibromatosis was diagnosed 9 years prior with a vestibular schwannoma. SRS to the residual tumour was given 3 months later. During the current hospitalisation, he was reoperated where histology confirmed a MPNST. All 15 MPNST cases were analysed, showing a 77% female predominance presenting a malignant transformation at a mean age of 51. The diagnosis was made at a mean time of 74 months after SRS. The mean survival time after diagnosis was 16 months. MPNST arising from benign vestibular schwannoma after SRS treatment is an uncommon but devastating complication.

Obstructive Hydrocephalus and Chemical Meningitis Secondary to a Ruptured Spinal Epidermoid Cyst.

BACKGROUND: Epidermoid cysts of the spinal cord may rupture, resulting in keratin dissemination in the subarachnoid space, in the ventricles, and along the central canal of the spinal cord causing meningitis, myelopathic changes, or hydrocephalus. CASE DESCRIPTION: A 53-year-old woman with no past medical history presented with a 2-week history of headache located in the occipital region associated with neck pain. Brain magnetic resonance imaging demonstrated multiple fat droplets scattered throughout the subarachnoid and intraventricular spaces with significant edema of the right posterior temporoparietal lobes with trapping of the right temporal horn of the lateral ventricle and atrium. An intracranial lesion could not be observed in the study. The spinal region was suspected as the possible culprit, and spinal imaging showed a large cystic lesion at the level of the conus medullaris. The patient underwent neuronavigation endoscopic exploration of the right lateral ventricle with flushing of the keratin particles followed by a posterior lumbar decompression with resection of the epidermoid cyst. Pathology was consistent with an epidermoid cyst. Successful recovery with improvement in symptoms was quickly observed. CONCLUSIONS: When an epidermoid cyst is suspected but no intracranial lesion is found, the intraspinal area should be studied. Rupture of a spinal epidermoid cyst may cause meningitis and inflammation producing obstructive hydrocephalus. We present this rare entity and describe the diagnostic and surgical techniques used.