HCA is a tumoral lesion, often cystic and with a mural nodule, that occurs commonly within the cerebellum, but it may occur all over the central nervous system. It has a slow growth rate and is classified as grade I by the World Health Organization. It is most common in pediatric population and represents 10% to 15% of all pediatric brain tumors.
Histological classification consist of three types (type A, B and mixed). The typical presentation is a headache with vomiting associated to hydrocephalus. Other symptoms are related to cerebellar dysfunction (dysmetria, ataxia, nystagmus), compression to surrounding posterior fossa neuro-vascular structures (pyramidal signs, cranial nerve palsies) and a raised intracranial pressure.
The treatment of this lesion is a total surgical removal. The cyst wall is not neoplastic and need not to be removed. If the cyst wall enhances on MRI then it has to be removed. Currently the radiotherapy and radiosurgery are employed for the treatment of nonresectable recurrence or for recurrence with malignant histology.
In difficult cases, chemotherapy protocols for low-grade gliomas may be used. The risk of cerebro-spinal fluid diversion is significant and the endoscopic treatment for obstructive hydrocephalus should be considered. Patients with histological type A have 94% 10-yr survival, whereas those with type B had only 29% 10-yr survival. Serial imaging and close follow-up is very important in these patients because the recurrences generally occur within 3 yrs of surgery.
Histological classification consist of three types (type A, B and mixed). The typical presentation is a headache with vomiting associated to hydrocephalus. Other symptoms are related to cerebellar dysfunction (dysmetria, ataxia, nystagmus), compression to surrounding posterior fossa neuro-vascular structures (pyramidal signs, cranial nerve palsies) and a raised intracranial pressure.
The treatment of this lesion is a total surgical removal. The cyst wall is not neoplastic and need not to be removed. If the cyst wall enhances on MRI then it has to be removed. Currently the radiotherapy and radiosurgery are employed for the treatment of nonresectable recurrence or for recurrence with malignant histology.
In difficult cases, chemotherapy protocols for low-grade gliomas may be used. The risk of cerebro-spinal fluid diversion is significant and the endoscopic treatment for obstructive hydrocephalus should be considered. Patients with histological type A have 94% 10-yr survival, whereas those with type B had only 29% 10-yr survival. Serial imaging and close follow-up is very important in these patients because the recurrences generally occur within 3 yrs of surgery.
References
- Wellons III JC, Reddy AT, Tubbs RS, Oakes WJ. Update on the treatment of intracerebellar pilocytic astrocytomas. Contemporary Neurosurgery 25;9: May 15, 2003.
- Handbook of Neurosurgery - fifth edition - Mark S. Greenberg - ed. Thieme.
- Youmans JR, (ed) Neurological Surgery.3rd ed., WB Saunders, Philadelphia, 1990.
