Pseudoprogression in a PCNSL patient treated with pomalidomide. (A-B) The patient had stable disease after cycle 2 and (C) showed radiologic findings suggestive of progression of disease on restaging MRI of brain after cycle 4 without clinical deterioration. She was taken off study as per protocol. (D) Repeat MRI of brain 1 month later without any steroid or any other treatment showed radiologic improvement. This case is the patient 11 on Figure 2.