Fig. 3

Hematoxylin and Eosin (HE) staining ×200 (magnification) (A and B) A Fibrous meningioma, WHO Classification Grade I (of III). Elongated cells forming parallel or intersecting bundles with significant collagen fibers in-between. B Oligodendroglioma, IDH mutated and with 1p/19q codeletion, WHO Classification Grade II (of III). Glial neoplasm with infiltrative growth pattern, composed predominantly of cells with round and uniform nuclei, sometimes with peri-nuclear halo. There is focal nuclear atypia and rare figures of mitosis, as well as microcystic degeneration and reactive astrocytosis