**4. Conclusions**

**Genetic diagnosis**. This entity is defined by the presence of the K27 M mutation in the H3F3A (80%), HIST1H3B (20%), and HIST1H3C genes. The genetic profile is completed by mutations in the TP53 and ATRX genes, homozygous CDKN2A deletion, and MYC, CDK4/6, and

This type of tumor is not amenable for surgical treatment. The single debate is related to the role of biopsy. The actual accepted strategy is that biopsy (open or stereotactic) is indicated only in atypical tumors. The term of atypical is somehow unclear, but generally it is accepted that the unilateral extension of tumor and the presence of cystic components or focal hemor-

In centers with experience in stereotactic biopsy, this could be the method of choice. Otherwise, open surgery is performed, guided by the most superficial part of lesion or throughout the so-called "safe entry zone." In selected cases, surgical interventions can offer the opportunity of cytoreductive surgery, thus creating proper conditions for radiotherapy (**Figure 27**) [161].

Radiotherapy is the single recommendable therapy for this kind of lesions (**Figure 28**). A total dose between 54 and 60 Gy, administered in fractions of 1.8–2 Gy, is the actual recommendation of oncologists. No chemotherapy regimen was able to demonstrate a benefit in terms of survival. Corticosteroids are also administered during radiotherapy. After a period of symp-

Despite having a particular clinical evolution, pediatric tumors have been lumped together with the adult ones, according to the histopathological similarities [163]. We now know that their onset and progression genetic mechanisms are different. A well-defined entity that occurs predominantly in children is the one described above. As opposed to adult tumors,

**Figure 27.** T2W (a), FLAIR (b) and DWI (c) sequences of an infiltrative tumor into the brainstem and left cerebellar

PDGFRA amplifications [160].

130 Glioma - Contemporary Diagnostic and Therapeutic Approaches

rhages offer a rationale for surgery.

**3.10. Pediatric diffuse astrocytic tumors**

peduncles.

tom amelioration, the tumor will inevitably progress [162].

*3.9.1. Multimodal treatment*

The 2016 brain tumor classification represents an important step forward in the introduction of molecular diagnosis in the daily current practice. This is also an important step toward a personalized patient-tailored multimodal management of brain tumors. Neurosurgeons, as part of a multidisciplinary team, need to be familiarized with all the aspects regarding specific brain tumors in order to offer the best chance to their patients and to prolong survival with a good quality of life.
