An example of radiation-induced vascular malformation in a patient with a non-small cell lung cancer brain metastasis post treatment (patient #3). A, C: Pre-surgical contrast-enhanced T1-weighted MRI and the calculated TRAMs depicting a small blue mass on the border of the previous surgery site 29 months post SRS. B, D: Pre-surgical contrast-enhanced T1-weighted MRI and the calculated TRAMs depicting a small blue mass re-growing on the border of the previous surgery site 23 months post removal of the previous lesion and FSR. E–H H&E stained paraffin sections showing cavernoma-like vascular malformations, with back to back vascular channels, marked hyalinization and calcification. H: Immuno-histochemical staining for smooth muscle alpha-actin (SMA) showing only patchy immuno-reactivity in vessel walls, with near-absence in areas. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)