Pediatric de novo cerebral AVM: report of two cases and review of literature.

PURPOSE: Cerebral arteriovenous malformation (AVM) is traditionally thought of as a congenital diagnosis. In recent years, there has been infrequent reports of this neurovascular condition presenting as de novo entities. METHODS: The authors report two cases of pediatric patients who present with de novo cerebral AVMs. In both cases, the patients had magnetic resonance imaging (MRI) of the brain done as part of the work-up for first-onset seizures. At that point in time, the scans were unremarkable. After a latent period of approximately 6 and 9 years respectively, a repeated MRI brain scan showed evidence of de novo AVM for each patient. RESULTS: Both patients did not have radiological evidence of cerebral AVM during their first presentation of seizures. However, a repeated MRI brain scan after a period of 6 and 9 years demonstrated new findings of cerebral AVM for each patient. CONCLUSIONS: Currently, the disease of cerebral de novo AVM remain as an ambiguous condition that is poorly understood. With the advances in molecular diagnostics, there are possibilities of exploring biochemical profiles for better understanding of the origin of cerebral AVMs. However, in the meantime, owing to the unpredictable nature of cerebral AVMs, clinicians should have increased awareness of this unique condition. This is especially important, as definitive treatment is available to prevent devastating neurological sequelae from cerebral AVM rupture.

Cystic Cavernoma of Fourth Ventricle in Pediatric Patient.

BACKGROUND: Cystic cerebral cavernomas belong to a rare subset of cavernous malformations in the brain. At present, there is limited information with regard to the demographics and etiology of this condition. CASE DESCRIPTION: The authors present a case of a previously well 13-year-old male who presented with symptoms secondary to a cystic lesion of the fourth ventricle compressing on his brainstem. He underwent stereotactic aspiration of the cystic lesion and insertion of an Ommaya reservoir in the same setting. Postoperatively, his symptoms improved. The cyst fluid did not yield any positive cytology or culture results. A repeat MRI brain did not demonstrate evidence of any underlying lesion. However, the patient was readmitted for hemorrhage into the region of his previous fourth ventricular lesion. Surgical evacuation of the haematoma was performed and intraoperative tissue was sent for pathological interrogation. The final histology reported a cavernoma. CONCLUSIONS: This is an unusual presentation of an intracranial vascular anomaly in a pediatric patient. Key features of the case include the diagnostic dilemma and management challenges faced from a neurosurgical perspective.

Atypical Teratoid Rhabdoid Tumor: Two Case Reports and an Analysis of Adult Cases with Implications for Pathophysiology and Treatment.

We present the first quantitative analysis of atypical teratoid rhabdoid tumors (ATRT) in adults, including two patients from our own institutions. These are of interest as one occurred during pregnancy and one is a long-term survivor. Our review of pathological findings of 50 reported cases of adult ATRT leads us to propose a solely ectodermal origin for the tumor and that epithelial-mesenchymal transition (EMT) is a defining feature. Thus, the term ATRT may be misleading. Our review of clinical findings shows that ATRT tends to originate in mid-line structures adjacent to the CSF, leading to a high rate of leptomeningeal dissemination. Thus, we hypothesize that residual undifferentiated ectoderm in the circumventricular organs, particularly the pituitary and pineal glands, is the most common origin for these tumors. We note that if growth is not arrested soon after diagnosis, or after the first relapse/progression, death is almost universal. While typically rapidly fatal (as in our first case), long-term remission is possible (as in our second). Significant predictors of prognosis were the extent of resection and the use of chemotherapy. Glial differentiation (GFAP staining) was strongly associated with leptomeningeal metastases (chi-squared p = 0.02) and both predicted markedly worse outcomes. Clinical trials including adults are rare. ATRT is primarily a disease of infancy and radiotherapy is generally avoided in those aged less than 3 years old. Treatment options in adults differ from infants in that cranio-spinal irradiation is a viable adjunct to systemic chemotherapy in the adult population. Given the grave prognosis, this combined approach appears reasonable. As effective chemotherapy is likely to cause myelosuppression, we recommend that stem-cell rescue be available locally.