CNS nontumor
Toxic and metabolic disorders
Radiation injury
Author: Kymberly A. Gyure, M.D.
Last author update: 1 November 2014
Last staff update: 8 March 2023 (update in progress)
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Radiation injury CNS [title]
Table of Contents
Definition / general | Terminology | Sites | Pathophysiology | Clinical features | Diagnosis | Radiology description | Radiology images | Case reports | Treatment | Gross description | Microscopic (histologic) description | Cytology description | Differential diagnosis | Additional referencesCite this page: Gyure K.A. Radiation injury. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnsradiationinjury.html. 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
Terminology
- 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
Sites
- White matter in field of previous radiation therapy
Pathophysiology
- 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
Diagnosis
- 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:
Radiation necrosis of pons
Abnormal enhancement in left occipital lobe
Irregular enhancement around surgical cavity
Case reports
- 54 year old man with visual field loss and brain mass (N Engl J Med 2012;366:2112)
- 57 year old man with radiation necrosis of pons after radiotherapy for nasopharyngeal carcinoma (J Radiol Case Rep 2012;6:9)
- Radionecrosis mimicking metastatic tumor of cerebral hemisphere (Folia Neuropathol 1995;33:55)
Treatment
- 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
Additional references
