CNS nontumor

Toxic and metabolic disorders

Radiation injury

Last author update: 1 November 2014
Last staff update: 8 March 2023 (update in progress)

Copyright: 2002-2023,, Inc.

PubMed Search: Radiation injury CNS [title]

Kymberly A. Gyure, M.D.
Page views in 2022: 1,125
Page views in 2023 to date: 365
Cite this page: Gyure K.A. Radiation injury. website. Accessed March 26th, 2023.
Definition / general
  • Radiation therapy is commonly used as adjuvant therapy for both primary and secondary malignant CNS neoplasms
  • Causes a spectrum of toxic CNS effects ranging from subclinical white matter injury to overt brain necrosis
  • CNS lesions secondary to radiation therapy are typically classified based on their chronicity
    • Acute and subacute forms of radiation injury are due to blood brain barrier disruption and are generally reversible
    • Late or delayed radiation necrosis (develops months to years after irradiation) is a potentially disabling complication and is generally considered irreversible
  • White matter in field of previous radiation therapy
  • Primary mechansim of radiation necrosis is thought to be microvascular injury resulting in tissue hypoxia and necrosis
Clinical features
  • Neurologic symptoms depend on location of lesion and are essentially indistinguishable from symptoms due to a mass of any kind
  • In patients who have received radiation therapy for neoplasm, the principal clinical differential diagnosis is recurrent tumor
  • Advanced imaging techniques including PET can suggest a diagnosis of radiation necrosis but biopsy / resection of questionable lesions is often performed to rule out recurrent tumor
Radiology description
  • Imaging studies demonstrate well demarcated, peripherally contrast enhancing lesions in white matter which are often difficult to distinguish from recurrent tumor
Radiology images

Images hosted on other servers:
Missing Image Missing Image

Radiation necrosis of pons

Missing Image

Abnormal enhancement in left occipital lobe

Missing Image

Irregular enhancement around surgical cavity

Case reports
  • Anti-VEGF therapy has been used successfully in some cases of CNS radiation necrosis but this is considered experimental
Gross description
  • Firm, ill defined mass or soft, friable lesion with cystic degeneration involving white matter
Microscopic (histologic) description
  • Fibrinoid necrosis or hyalinization / fibrosis of blood vessels, dystrophic calcification and an inflammatory infiltrate consisting predominantly of macrophages
  • Radiation induced cytologic atypia
Cytology description
  • As in other nonneoplastic CNS lesions, the presence of macrophages on intraoperative cytologic preparations should suggest the diagnosis of radiation necrosis over recurrent tumor
Differential diagnosis
  • Recurrence of the tumor for which the patient received radiation therapy (typically glioblastoma): features which favor radiation therapy effect include a lack of peripheral pseudopalisading of cells around areas of necrosis, the presence of associated microcalcifications and hyaline thickening of blood vessels
Back to top
Image 01 Image 02