This case illustrates the importance of remembering that favoring pseudoprogression does not mean that no tumor will be present if biopsied, but rather that the apparent growth (i.e. progression) is due to treatment effect rather than true tumor growth.
The importance of this is that it will determine whether management should change (e.g. shift into second line salvage therapy) or push on. Prognostically pseudoprogression is probably desirable reflecting pronounced treatment effect. This is further supported by the fact that it is seen more frequently in tumors that are MGMT methylated.