Pilocytic astrocytomas in children: prognostic factors--a retrospective study of 80 cases.

OBJECTIVE: Pilocytic astrocytomas (PA) are Grade I brain tumors characterized by an excellent prognosis. In some cases, however, the patient has a bad outcome. The aim of our study was to search for the clinicopathological factors underlying the prognosis for patients with this disease.

METHODS: We reviewed the clinical, neuroradiological, and histopathological features of 80 PAs (33 cerebellar, 18 optochiasmatic, 16 brainstem, 7 spinal cord, 3 thalamic, 2 optic nerve, and 1 hemispheric) in pediatric patients.

RESULTS: Pathological examination revealed 58 classic PAs and 20 pilomyxoid astrocytomas, which are a histological variant of PAs. Two cases remained unclassified. The mean overall follow-up period was 58 months, the 5-year progression-free survival rate was 75%, and the 5-year survival rates were 100 and 92% after total and partial removal. Univariate statistical analysis revealed that partial resection, optochiasmatic PA localization, and pilomyxoid variant were associated with a worse prognosis, but the latter two parameters were too closely related to the extent of resection to be independent prognostic factors in multivariate analysis. Among the patients who underwent partial surgical removal, only invasion of the surrounding structures was related to prognosis.

CONCLUSION: PAs are benign tumors, but some clinicopathological factors, such as partial resection, optochiasmatic location, invasion of surrounding structures, and the pilomyxoid variant, have a worse prognosis.