Therapy-Induced Morphological Alterations in Brain Tumors

Routine therapeutic options for tumors of the brain or spinal cord comprise surgery, radiation and/or chemotherapy, all of which are associated with several possible complications. The most important consequences of brain tumor therapy are hemorrhage, acute brain swelling with external herniation of parts of the brain, CSF leaks, and coagulopathies. The anatomical location of surgical manipulation may have additional special effects, like diabetes insipidus following pituitary or adjacent base of the brain surgery. New techniques of radiotherapy applied in neurooncology such as “gamma knife” (stereotactic radiosurgery), intracavital brachytherapy, three dimensional conformal radiation, are also associated with iatrogenic changes in the brain. Pathologic changes induced by various radiotherapeutic modalities are discussed in this review, with special emphasis on terminology, timing and the importance of pathologic examination for assessing the tumor response to therapy, signs of peritumoral tissue damage and tumor recurrence. Therapy-induced secondary neoplastic lesions are also discussed.