Pathologic features of brain hemorrhage after radiation treatment: case series with somatic mutation analysis

J Stroke Cerebrovasc Dis. 2024 Jul;33(7):107699. doi: 10.1016/j.jstrokecerebrovasdis.2024.107699. Epub 2024 Mar 27.


Background: Radiation treatment for diseases of the brain can result in hemorrhagic adverse radiation effects. The underlying pathologic substrate of brain bleeding after irradiation has not been elucidated, nor potential associations with induced somatic mutations.

Methods: We retrospectively reviewed our department's pathology database over 5 years and identified 5 biopsy specimens (4 patients) for hemorrhagic lesions after brain irradiation. Tissues with active malignancy were excluded. Samples were characterized using H&E, Perl's Prussian Blue, and Masson's Trichrome; immunostaining for B-cells (anti-CD20), T-cells (anti-CD3), endothelium (anti-CD31), macrophages (anti-CD163), α-smooth muscle actin, and TUNEL. DNA analysis was done by two panels of next-generation sequencing for somatic mutations associated with known cerebrovascular anomalies.

Results: One lesion involved hemorrhagic expansion among multifocal microbleeds that had developed after craniospinal irradiation for distant medulloblastoma treatment. Three bleeds arose in the bed of focally irradiated arteriovenous malformations (AVM) after confirmed obliteration. A fifth specimen involved the radiation field distinct from an irradiated AVM bed. From these, 2 patterns of hemorrhagic vascular pathology were identified: encapsulated hematomas and cavernous-like malformations. All lesions included telangiectasias with dysmorphic endothelium, consistent with primordial cavernous malformations with an associated inflammatory response. DNA analysis demonstrated genetic variants in PIK3CA and/or PTEN genes but excluded mutations in CCM genes.

Conclusions: Despite pathologic heterogeneity, brain bleeding after irradiation is uniformly associated with primordial cavernous-like telangiectasias and disruption of genes implicated in dysangiogenesis but not genes implicated as causative of cerebral cavernous malformations. This may implicate a novel signaling axis as an area for future study.

Keywords: Adverse radiation effects; Case series; Hemorrhage; Mutation; Stereotactic radiosurgery.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Biopsy
  • Cerebral Hemorrhage / etiology
  • Cerebral Hemorrhage / genetics
  • Cerebral Hemorrhage / pathology
  • Class I Phosphatidylinositol 3-Kinases / genetics
  • Cranial Irradiation / adverse effects
  • DNA Mutational Analysis
  • Databases, Factual
  • Female
  • Genetic Predisposition to Disease
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Intracranial Arteriovenous Malformations / genetics
  • Intracranial Arteriovenous Malformations / pathology
  • Intracranial Arteriovenous Malformations / radiotherapy
  • Intracranial Hemorrhages / etiology
  • Intracranial Hemorrhages / genetics
  • Intracranial Hemorrhages / pathology
  • Male
  • Middle Aged
  • Mutation*
  • PTEN Phosphohydrolase / genetics
  • Phenotype
  • Radiation Injuries* / etiology
  • Radiation Injuries* / genetics
  • Radiation Injuries* / pathology
  • Retrospective Studies
  • Risk Factors
  • Young Adult


  • Class I Phosphatidylinositol 3-Kinases
  • PTEN Phosphohydrolase
  • PTEN protein, human
  • PIK3CA protein, human