Desmoplastic non-infantile astrocytic tumor with BRAF V600E mutation

Desmoplastic infantile astrocytoma with atypical phenotype, PTEN homozygous deletion and BRAF V600E mutation

Desmoplastic infantile astrocytoma (DIA) is rare, cystic and solid tumor of infants usually found in superficial cerebral hemispheres. Although DIA is usually benign, uncommon cases bearing malignant histological and aggressive clinical features have been described in the literature. We report a newborn patient who was diagnosed with a DIA and died postresection. Pathologic examination revealed that the main part of the tumor had benign features, but the internal region showed areas with a more aggressive appearance, with higher-proliferative cells, anaplastic GFAP positive cells with cellular polymorphism, necrosis foci, vascular hyperplasia with endothelial proliferation and microtrombosis. Genetic study, performed in both regions of the tumor, showed a BRAF V600E mutation and a homozygous deletion in PTEN, without changes in other relevant genes like EGFR, CDKN2A, TP53, NFKBIA, CDK4, MDM2 and PDGFRA. Although PTEN homozygous deletions are described in gliomas, the present case constitutes the first report of a PTEN mutation in a DIA, and this genetic feature may be related to the malignant behavior of a usually benign tumor. These genetic findings may point at the need of further and deeper genetic characterization of DIAs, in order to better understand the biology of this tumor and to obtain new prognostic approaches, a better clinical management and targeted therapies, especially in malignant cases of DIA.

Purely Intraventricular Desmoplastic Infantile Astrocytoma

Desmoplastic infantile astrocytomas (DIAs) are rare pediatric tumors characterized by superficial brain cortex involvement, along with the meninges of the supratentorial compartment, and are classified as grade I neoplasms according to the 2016 World Health Organization. A 5-year-old girl child patient was admitted to our unit with abnormal decorticate posturing, bilateral mydriasis with weak pupillary light reflex, and brisk lower limbs reflexes. Her medical history was unremarkable. Magnetic resonance imaging of the brain revealed a massive lesion with bilateral intraventricular growth mainly prevailing on the left and involving the ipsilateral foramen of Monro. After external ventricular drainage positioning, Dandy's transfrontal transcortical approach to the left lateral ventricle, a meticulous ependymal microsurgical dissection of the lesion was performed, resulting in an excision of the cystic component of the left lateral ventricle. A gross total removal of the lesion was performed with an en bloc resection of the deeper cystic part. Thirty days after surgery, the patient presented with fluent speech, conserved axial, and extremity sensorimotor functions, except a mild central facial paresis which progressively improved. To the best of our knowledge, this is the first case of DIA characterized by purely intraventricular growth. Tumor recurrence, although considered rare, represents an unpredictable event. Therefore, an adequate follow-up must be reserved for each patient.

Infantile and Noninfantile Desmoplastic Astrocytoma and Ganglioglioma: Only Different Age of Onset?

OBJECTIVE

The purpose of this study was to investigate clinical, pathological, and prognostic discrepancies between infantile and noninfantile desmoplastic astrocytoma/ganglioglioma patients.

METHODS

From January 2012 to December 2019, we retrospectively reviewed patients aged <18 years who underwent craniotomies at Beijing Tiantan Hospital. Patients diagnosed with desmoplastic infantile astrocytoma and ganglioglioma (DIA/DIG) were included.

RESULTS

The group consisted of 9 infantile patients and 8 noninfantile patients. The mean age of onset was 30.11 months in infantile patients and 103.75 months in noninfantile patients. Comparing with infantile patients, noninfantile patients had a mild female predominance (P = 0.335). The most common presentation in noninfantile patients was seizure (n = 4, 50%), whereas abnormal head circumference (n = 3, 33.3%) was the most common presentation in the infantile group. All cases showed a ki-67 index <2%. Preoperative tumor volume in infantile patients (213.98 cm³) was larger than that in noninfantile patients (21.99 cm³) (P = 0.043). Gross total resection was achieved in 5 (55.6%) infantile patients and 6 (75%) noninfantile patients (P = 0.62). All patients are alive by last follow-up visit, and 1 infantile patient recurred 8 months postoperative.

CONCLUSIONS

Infantile and noninfantile patients with DIA/DIGs share similar clinical and histopathological features. Compared with infantile patients, noninfantile patients tend to have different symptom predominance. Lesions in noninfantile patients are prone to present with different cystic-solid patterns and smaller volume. Patients with DIA/DIGs have favorable prognosis regardless of extent of resection.

Desmoplastic Infantile Ganglioglioma/Astrocytoma (DIG/DIA) Are Distinct Entities with Frequent BRAFV600 Mutations

Desmoplastic infantile ganglioglioma (DIG) and desmoplastic infantile astrocytoma (DIA) are extremely rare tumors that typically arise in infancy; however, these entities have not been well characterized in terms of genetic alterations or clinical outcomes. Here, through a multi-institutional collaboration, the largest cohort of DIG/DIA to date is examined using advanced laboratory and data processing techniques. Targeted DNA exome sequencing and DNA methylation profiling were performed on tumor specimens obtained from different patients (n = 8) diagnosed histologically as DIG/DIGA. Two of these cases clustered with other tumor entities, and were excluded from analysis. The remaining 16 cases were confirmed to be DIG/DIA by histology and by DNA methylation profiling. Somatic BRAF gene mutations were discovered in 7 instances (43.8%); 4 were BRAFV600E mutations, and 3 were BRAFV600D mutations. Three instances of malignant transformation were found, and sequencing of the recurrence demonstrated a new TP53 mutation in one case, new ATRX deletion in one case, and in the third case, the original tumor harbored an EML4-ALK fusion, also present at recurrence. DIG/DIA are distinct pathologic entities that frequently harbor BRAFV600 mutations. Complete surgical resection is the ideal treatment, and overall prognosis is excellent. While, the small sample size and incomplete surgical records limit a definitive conclusion about the risk of tumor recurrence, the risk appears quite low. In rare cases with wild-type BRAF, malignant progression can be observed, frequently with the acquisition of other genetic alterations.Implications: DIG/DIA are a distinct molecular entity, with a subset frequently harboring either BRAF V600E or BRAF V600D mutations. Mol Cancer Res; 16(10); 1491-8. ©2018 AACR.

Desmoplastic infantile astrocytoma/ganglioglioma with rare BRAF V600D mutation

BACKGROUND

Desmoplastic infantile astrocytoma (DIA) and desmoplastic infantile gangliogliomas (DIGs) are rare, massive, cystic and solid tumors of infants usually found in superficial cerebral hemispheres. They manifest prominent desmoplastic stroma, admixed neoplastic astrocytes, primitive-appearing small cells, and additional neoplastic ganglion cells in the case of DIGs. While v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is found in up to 50% of pediatric gangliogliomas, two recent studies found that it was rare in DIA/DIGs; we sought to assess BRAF status in DIA/DIGs from our institution.

PROCEDURE

Departmental files from 2000 to 2016 were reviewed to identify cases. Clinical, neuroimaging, histological, and immunohistochemistry (IHC) features were assessed; the latter included IHC for astrocytic and neuronal markers and BRAF VE1. BRAF mutational assessment by Sanger and next-generation sequencing was attempted in all cases.

RESULTS

All six identified cases (four males-two females; three DIA-three DIG) occurred in children <1-year old, were large, cerebral-hemispheric, cystic and solid, and enhancing tumors. Only one case, a DIG with prominent aggregates of neoplastic ganglion cells, showed either BRAF VE1 IHC positivity or mutation by Sanger and next-generation sequencing (rare c. 1799_1800delinsAT; p. V600D). Four of six archival cases were BRAF VE1 IHC negative, but failed mutational sequencing.

CONCLUSION

Five of six classic DIA/DIGs were negative for BRAF mutation; previous series have identified BRAF mutation in two of 18 and one of 14 cases, although all were the more common BRAF V600E. We were unable to find other examples of glial tumors in public databases with this rare BRAF V600D mutation. Identification of BRAF mutational opens the possibility of BRAF-targeted therapies for the subset of DIA/DIG that clinically progress postresection.

Atypical imaging in a desmoplastic non-infantile astrocytoma

INTRODUCTION

Desmoplastic infantile tumors, especially desmoplastic astrocytomas, are uncommon neoplasms that are generally seen within first 2 years of life. Their occurrence in slightly older children is very rare. The typical radiological appearance is a large cystic lesion with small enhancing solid part.

CASE

In the present report, we describe a 10-year-old child with atypical appearance of desmoplastic non-infantile astrocytoma which was predominantly solid on imaging.

CONCLUSION

Although rare, desmoplastic astrocytomas may present even in older children and should be considered in the differential diagnoses. These tumors may present as predominantly solid enhancing lesions and add to the radiological dilemma.

Desmoplastic astrocytoma: new insights into its clinical profile, diagnosis, and treatment

BACKGROUND

Desmoplastic astrocytoma (DA) is a rare intracranial tumor which usually affects pediatric patients. The aim of this study is to describe the clinical features and management of DA based on a joint analysis of the cases reported in the scientific literature.

MATERIAL AND METHODS

A thorough review was carried out, gathering those pathologically proven DAs reported since the first description of this entity. Two new own cases were included in order to illustrate this review. Epidemiological, clinical, radiological, therapeutic, and follow-up data were analyzed with the software SPSS version 20.

RESULTS

A total of 52 DAs were recorded. Most cases occurred in the first 2 years of life, although older patients were also reported. Patients mainly presented symptoms and signs of elevated intracranial pressure. According to their radiological features, we were able to classify DAs in four main groups, with distinct differential diagnosis and prognosis. After treatment, 14.2 % of patients presented persistent neurological impairment and the mortality rate was close to 10 %.

CONCLUSION

DAs can be diagnosed at any age from birth to adolescence. These neoplasms can show up a wider range of radiological morphologies than previously thought. Surgery represents the treatment of choice for DAs, although chemotherapy can also be useful in the setting of recurrence or progression of the disease. Those DAs lacking classic radiological features, especially type 4 tumors, were linked with a poorer clinical outcome.

Diagnostic, prognostic and predictive relevance of molecular markers in gliomas

The advances of genome-wide 'discovery platforms' and the increasing affordability of the analysis of significant sample sizes have led to the identification of novel mutations in brain tumours that became diagnostically and prognostically relevant. The development of mutation-specific antibodies has facilitated the introduction of these convenient biomarkers into most neuropathology laboratories and has changed our approach to brain tumour diagnostics. However, tissue diagnosis will remain an essential first step for the correct stratification for subsequent molecular tests, and the combined interpretation of the molecular and tissue diagnosis ideally remains with the neuropathologist. This overview will help our understanding of the pathobiology of common intrinsic brain tumours in adults and help guiding which molecular tests can supplement and refine the tissue diagnosis of the most common adult intrinsic brain tumours. This article will discuss the relevance of 1p/19q codeletions, IDH1/2 mutations, BRAF V600E and BRAF fusion mutations, more recently discovered mutations in ATRX, H3F3A, TERT, CIC and FUBP1, for diagnosis, prognostication and predictive testing. In a tumour-specific topic, the role of mitogen-activated protein kinase pathway mutations in the pathogenesis of pilocytic astrocytomas will be covered.