Illustrative Case. Preoperative MRI of patient Nr. 18, showing a parietooccipital left sided intra-axial lesion with infiltration of the splenium of the corpus callosum. The lesion is centrally necrotic with dense contrast enhancement around the margins. The measured tumor volume is 36.5 mm3 and edema volume 231.4mm3 with 15 mm midline shift and consecutive hydrocephalus. Clinically the patient initially presented with a Gerstmann syndrome and neurocognitive deficits. The preoperative ICP was measured 9.08 mmHg on the left side and 11 mmHg on the right side. A performed biopsy diagnosed a B-cell type non-hodgkin lymphoma