[Computed tomographic and magnetic resonance tomographic findings in pilocytic astrocytoma].

PURPOSE: In a retrospective study we examined the predilection sites, the CT and MR morphology and the contrast behaviour of intracranial pilocytic astrocytoma (PA) in a large number of patients.

MATERIAL AND

METHODS

The study consists of 47 patients (18 male, 29 female, mean age 10.1 years) with histologically proven PA.

RESULTS

The chief predilection site turned out to be the hypothalamic region (15/47 = 32%). The other regions involved were (in descending order): brain hemispheres 8/47 = 17%; cerebellar vermis 7/47 = 15%, cerebellar hemispheres; thalamic nuclei and pontomedullar region 4/47 = 8.5% each; pineal gland 2/47 = 4%; pons, lamina tecti and optic fascicle 1/47 = 2% each. The PA presented 24/47 = 51% cysts; 7/47 = 15% calcifications; 2/47 = 4% necrosis and 1/47 = 2% perifocal oedema. In three cases (3/47 = 6%) CT and MRI showed no contrast enhancement.

CONCLUSION

PA appear in almost all brain regions but there is a clear preference of the hypothalamic region. PA of the hypothalamic region are a special subgroup. They are often associated with neurofibromatosis 1, tend to infiltrate surrounding structures, and to disseminate into the intracranial and spinal subarachnoid space.