Pilocytic astrocytomas as hamartomas: implications for treatment

Characteristics, survival and incidence rates and trends of pilocytic astrocytoma in children in the United States; SEER-based analysis

INTRODUCTION

Pilocytic astrocytoma (PA) is a neurological neoplasm and a common neurological tumor among children. No recent reports have studied the recent demographic characteristics of PA cases in the US.

METHODOLOGY

We used the Surveillance, Epidemiology, and End Results (SEER) Program to retrieve data on children diagnosed with PA between 2000 and 2015. We calculated the incidence, annual percentage changes (APC), and survival.

RESULTS

Our study included 3084 children with PA, with an incidence of 8.227 per 1,000,000 person-years, being highest among whites (9.062), and children aged 1-4 year (11.175). Overall incidence in children increased significantly over the study period, with an APC of 0.825% (95% CI[0.027-1.630], P = .044). Moreover, incidence among blacks increased significantly over the study period (APC = 3.466%, 95% CI[0.342-6.688], P = .032), but did not change among other races. The relative 5-year survival of included patients was 95.3%, with patients younger than 1 year having the worst survival.

CONCLUSIONS

Overall PA incidence and incidence among blacks has been increasing last decade. Additionally, PA survival was found to be worse among infants. Further studies are also needed to investigate the effect of the age and race on the incidence and survival of PA.

Transcriptional profiles of pilocytic astrocytoma are related to their three different locations, but not to radiological tumor features

Background

Pilocytic astrocytoma is the most common type of brain tumor in the pediatric population, with a generally favorable prognosis, although recurrences or leptomeningeal dissemination are sometimes also observed. For tumors originating in the supra-or infratentorial location, a different molecular background was suggested, but plausible correlations between the transcriptional profile and radiological features and/or clinical course are still undefined. The purpose of this study was to identify gene expression profiles related to the most frequent locations of this tumor, subtypes based on various radiological features, and the clinical pattern of the disease.

Methods

Eighty six children (55 males and 31 females) with histologically verified pilocytic astrocytoma were included in this study. Their age at the time of diagnosis ranged from fourteen months to seventeen years, with a mean age of seven years. There were 40 cerebellar, 23 optic tract/hypothalamic, 21 cerebral hemispheric, and two brainstem tumors. According to the radiological features presented on MRI, all cases were divided into four subtypes: cystic tumor with a non-enhancing cyst wall; cystic tumor with an enhancing cyst wall; solid tumor with central necrosis; and solid or mainly solid tumor. In 81 cases primary surgical resection was the only and curative treatment, and in five cases progression of the disease was observed. In 47 cases the analysis was done by using high density oligonucleotide microarrays (Affymetrix HG-U133 Plus 2.0) with subsequent bioinformatic analyses and confirmation of the results by independent RT-qPCR (on 39 samples).

Results

Bioinformatic analyses showed that the gene expression profile of pilocytic astrocytoma is highly dependent on the tumor location. The most prominent differences were noted for IRX2, PAX3, CXCL14, LHX2, SIX6, CNTN1 and SIX1 genes expression even within different compartments of the supratentorial region. Analysis of the genes potentially associated with radiological features showed much weaker transcriptome differences. Single genes showed association with the tendency to progression.

Conclusions

Here we have shown that pilocytic astrocytomas of three different locations can be precisely differentiated on the basis of their gene expression level, but their transcriptional profiles does not strongly reflect the radiological appearance of the tumor or the course of the disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1810-z) contains supplementary material, which is available to authorized users.

Ophthalmological assessment of children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder, caused by mutations in the NF1 gene, located on chromosome band 17q11.2. In 1988, the National Institutes of Health created specific criteria for the diagnosis of NF1. Four cardinal criteria are assessed through ophthalmological screening: Lisch nodules, optic pathway glioma, a distinctive osseous lesion (sphenoid dysplasia), and the (orbital) plexiform neurofibroma. NF1 patients are prone to the development of central and peripheral nervous system tumors. Especially young children are at risk for growing optic pathway gliomas that can threaten their sight. From an early age, children with NF1 undergo regular ophthalmological examinations. Little is known about the natural progress of these clinical features and the guidelines for screening and follow-up are controversial. Several questions remain unanswered.

CONCLUSION

Most of these questions could be solved by better understanding of the natural history of optic pathway gliomas. There is a tendency towards using vision as a primary objective in clinical treatment trials; this way we can evaluate new treatment strategies and focus specifically on visual evolution so we will be able to select even more carefully which patient would benefit treatment. For future clinical trials, a standardized visual acuity assessment protocol is therefore mandatory.

Endoscopic disconnection of hypothalamic astrocytoma causing gelastic epilepsy. Case report

The authors report on a case of juvenile pilocytic astrocytoma (JPA) and concomitant hypothalamic hamartoma (HH) with gelastic epilepsy that was successfully treated with endoscopic disconnection. This 6-year-old girl presented with prolonged, medically intractable gelastic seizures that were often followed by generalized tonic seizures. An enhancing, low-grade hypothalamic tumor was identified on MR images obtained when she was 11 months old, but no surgical intervention was attempted at that time apart from bur hole drainage of a chronic subdural hemorrhage. In the first surgery, performed when she was 6 years of age, the authors attempted disconnection and tumor sampling; the lesion was revealed to be a JPA. A second endoscopic disconnection was performed 1 year later to improve seizure control and obtain a pathological specimen from the nonenhancing contralateral side. The pathological results after the second surgery revealed that the enhancing mass was a spontaneously regressing JPA and the contralateral nonenhancing mass was an HH. The HH was found as latent tumor and the JPA was the mass causing gelastic epilepsy. To the authors' knowledge, this is the first report of a patient with a spontaneously regressing JPA and concomitant HH, both of which were treated by endoscopic disconnection.