**Molecular Advances in Glioblastoma Neuropathology**

Jens Schittenhelm and Marco Skardelly

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62670

#### **Abstract**

Glioblastoma is the most frequent and malignant brain tumor with a wide variety of morphological appearances. For a long time, the tumors were classified either as primary ("de novo") glioblastomas that develop rapidly in elderly patients or as secondary glioblastomas with clinical or histological progression from low-grade diffuse astrocytoma or anaplastic astrocytoma. Recent data from the comprehensive genetic characterization of these tumors identified a number of common and diverg‐ ing alterations and pathways that allow future stratification of glioblastomas into several age-dependent biological subgroups. While the histological classification of diffuse gliomas based on the WHO grading scheme is still necessary, the use of additional meaningful immunohistochemical (and mutation-specific) markers, such as IDH R132H, ATRX, and H3F3A K27M, has improved routine diagnosis. In recent years, the spectrum of clinically relevant molecular markers has expanded. The utility of MGMT, ATRX, TERT, H3F3A and LOH 1p/19q in predicting prognosis and response to therapy in routine diagnostic settings is discussed.

**Keywords:** neuropathology, histopathology, immunohistochemistry, molecular classi‐ fication, glioma
