Case report of recurrent anaplastic oligodendroglioma with mixed astrocytic components and pathological discordance of tumor progression

We present a case of a patient with the initial diagnosis of oligoastrocytoma WHO grade II. After multiple previous treatments and transformation to an anaplastic oligoastrocytoma WHO grade III, imaging after radiotherapy showed another tumor progression. Histopathological analysis after tumor resection confirmed parts of an astrocytic and an oligodendroglial tumor with extensive therapy-related changes. This constellation is not sufficiently covered by the current classification system and currently described as a diffuse glioma.