The diagnosis of pseudoprogression can be difficult and knowledge of timing of the scan relative to chemoradiotherapy is crucial (typically ~3 months post end of chemoradiotherapy, but commonly seen within 0 - 6 months). 

This patient was also more likely to demonstrate pseudoprogression as their tumor is MGMTmethylated (and thus alkylating agents e.g. temozolomide used in the Stupp protocol will have greater efficacy). 

It is also crucial to realize that it is not a question of pseudoprogression OR persistence presence of tumor (or even probably tumor growth); both can be occurring simultaneously. It is really a question of determining which process is dominant and accounts for the imaging features. 

In this case at least part of the initially progressive enhancement, which abates, was due to pseudoprogression, however by the time we see the last study we clearly also have disease progression.