Haemorrhage into a Pilocytic Astrocytoma

This 12-year-old boy presented acutely obtunded, and was found to have a haemorrhage into a cystic posterior fossa mass, which was confirmed to be a pilocytic astrocytoma. Haemorrhage is a rare, but recognised complication.
Pilocytic astrocytomas (also known as polar spongioblastoma or juvenile pilocytic astrocytoma (JPA) ) are low grade astrocytoma (WHO Grade I) found in young patients. Indeed they are the most common primary brain tumour of childhood, accounting for 5 - 10% of all gliomas. They are slow-growing well-circumscribed tumours with a good prognosis following treatment (>70% 20 year survival).
Typically (50%) they have a large cystic component with a brightly enhancing mural nodule. Usually the cyst wall does not enhance much if at all - only the nodule need be resected to effect cure. Up to 20% may demonstrate some calcification. A smaller proportion (40%) demonstrate more hetereogenous enhancement. Only 10% are completely solid.
For more about pilocytic astrocytomas please visit Radiopaedia.org here.
References:
1. Diagnostic Imaging - Brain - Osborn
2. Liana Beni-Adani et al “Cyst Wall Enhancement in Pilocytic Astrocytoma: Neoplastic or Reactive Phenomena” Pediatric Neurosurgery 2000;32:234-239
Credit: Dr Frank Gaillard
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