A 13-year-old male with a history of cranial surgery for medulloblastoma and radiotherapy history both on cranial and spinal area. After 5 years of tumour-free follow-up MR images, his last brain MR scan revealed a hemorrhagic tumour in the right temporal lobe. He had no neurologic symptoms.
T2 -Weighted (T2W) axial brain MR image demonstrated a hemorrhagic mass, approximately 2 cm in diameter at the right temporal lobe. The signal was heterogeneous due to blood and for the same reason hyperintensity on T1 W image. Axial FLAIR image showed perilesional oedema. Diffusion-weighted image (DWI) and apparent diffusion coefficient (ADC) map showed diffusion restriction due to haemorrhage. Vein bold image indicated prominent signal loss due to blood products. Slight enhancement of the lesion seen on postcontrast image (Fig 1).
Follow-up 6 months later, T2 W axial image showed that the mass lesion shrinked prominently. Vein bold image displayed typical cavernoma appearance. Perilesional oedema disappeared on FLAIR image, as well as diffusion restriction and T1 hyperintensity due to acute haemorrhage was diminished. Finally, contrast enhancement on lesion was also absent on follow-up imaging (Fig 2).
Cavernous malformations are known as congenital lesions in general, but radiation is another known cause of them. De novo cavernomas mostly occur in pediatric patients especially treated with radiotherapy for glioma, medulloblastoma, or ALL . Gaensler et al. reported cavernomas appeared after radiotherapy in 20 patients with the dose of 24 to 78 Gy in the latent period of 5 months to 20 years . Medulloblastoma is the leading primary tumour for radiation-induced cavarnomas . Maeder et al. reported a case with primary radiation-treated medulloblastoma and after a 3-year follow-up, there was a hemorrhagic mass which is pathologically proven cavernoma . But, de novo cavernomas occur even with the radiosurgery for the another cavernoma . Cavernous malformations induced by radiation can also occur in adults which is less common in comparison with children. There are few case reports for adults caused by radiation in the literature [5, 6].
In a patient with medulloblastoma diagnosis, cavernomas can be misdiagnosed as tumour recurrence because of their rapid growth, tumoral haemorrhage, diffusion restriction, enhancement and perilesional oedema; but prominent blooming on susceptibility-weighted images and hypointense rim on T2W sequence are typical for cavernomas [1-4].
Chronic encapsulated hematomas are the other late complication of radiosurgery, especially for arteriovenous malformations. They usually tend to be symptomatic and have more perilesional parenchymal oedema. To manage these usually, total capsule removed surgically .
In the literature, mostly symptomatic cases were treated with surgery and asymptomatic cases were followed up conservatively for radiation-induced cavernomas .
The hemorrhagic mass was conservatively managed with the corticosteroids and no additional surgery was planned. On follow-up images, approximately 6 months later the mass dimensions were reduced considerably and the typical cavernoma lesion appeared. Cavernoma and encapsulated arteriovenous fistulas are the rare complications of radiosurgery or radiotherapy especially seen on higher radiation doses and younger ages as discussed in background.
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