Genetic and expression profiles of cerebellar liponeurocytomas.

Cerebellar liponeurocytoma, a rare, newly identified CNS neoplasm of adults, is characterized by advanced neuronal/neurocytic and focal lipomatous differentiation, low proliferative potential and a favorable clinical prognosis. Despite the different age distribution and benign biological behavior, the cerebellar liponeurocytoma shares several features with the cerebellar medulloblastoma, which may include an origin from the periventricular matrix of the fourth ventricle or the external granular layer of the cerebellum. To establish the genetic profile of cerebellar liponeurocytomas, we have formed an international consortium and collected tumor samples from 20 patients. DNA sequencing revealed TP53 missense mutations in 4 (20%) of 20 cerebellar liponeurocytomas, a frequency higher than in medulloblastomas. There was no case with PTCH, APC, or beta-catenin mutations, each of which may be present in subsets of medulloblastomas. Isochromosome 17q, a genetic hallmark of classic medulloblastomas, was not observed in any of the cases investigated by FISH analysis. cDNA array analyses were carried out on 4 cerebellar liponeurocytomas, 4 central neurocytomas, and 4 classic medulloblastomas. Cluster analysis of the cDNA expression data of 1176 genes grouped cerebellar liponeurocytomas close to central neurocytomas, but distinct from medulloblastomas. These results suggest cerebellar liponeurocytoma as a distinct tumor entity that is genetically different from medulloblastoma. Furthermore, the cDNA expression array data suggest a relationship to central neurocytomas, but the presence of TP53 mutations, which are absent in central neurocytomas, suggests that their genetic pathways are different.

Minimally invasive lumbar discectomy in obese patients.

OBJECTIVE: To assess patient outcomes and complication rates after minimally invasive lumbar microdiscectomy in an obese patient population. METHODS: A retrospective clinical review of 32 patients with a body mass index of 30 kg/m or greater undergoing lumbar minimally invasive discectomy was performed. The initial chart review was followed by phone interview if all information could not be obtained from chart review. Demographic and pertinent pre-, peri-, and postoperative data were obtained. RESULTS: Favorable clinical outcomes were obtained in all patients except one, indicating that they would undergo operative intervention again. Most patients reported minimal or no leg or back pain. Twenty-five of the patients did not require any chronic analgesia. The overall complication rate was 12.5%. Two patients had recurrent disc herniations requiring reoperation and one patient required fusion for a pars defect and subsequent subluxation. CONCLUSION: Lumbar minimally invasive discectomy is our preferred surgical technique for symptomatic disc herniations in this patient population. Decreased incision length and a trend toward reduced infectious complications are the primary reasons. We feel that, given the comorbidities often found in this patient population, a minimally invasive technique will supplant open approaches in the near future.