gms | German Medical Science

Objective: Pilocytic astrocytomas (piloA) account for up to 25% of pediatric brain tumors. They are usually benign growths (WHO grade I) and are most commonly found in the deep midline structures, the brainstem and the cerebellum. Lobar tumors are much less common. Histologically anaplastic tumors are assigned to WHO grade III. piloA of an intermediate histological phenotype are classified as WHO grade II tumors by some neuropathologists. Pilomyxoid astrocytomas can be distinguished from piloA by certain histological features. The literature contains only scarce data on piloA in adults. Hence, we reviewed our experience with piloA in this latter patient group.

Methods: Between 1995 and 2005, we operated on n=43 (26f/17m) patients >16 years (mean: 31±4 years) for a piloA. Patients <16 years at the time of their first operation were excluded from analysis. Relevant clinical information was obtained through a chart review. Excluding 5 patients undergoing surgery within the last three months, mean follow-up was 5±3 years.

Results: 7 patients (18%) had chronic epilepsy. We observed 21 (49%) lobar (including 10 temporal, 5 parietal, and 3 insular tumors), and 12 (28%) cerebellar piloA. In 6/43 (14%) patients, a WHO grade II tumor and in a further 6/43 (14%) patients a grade III tumor was diagnosed either initially or at surgery for recurrence. Excluding 5 patients with a follow-up of <3 months, tumor recurrence or progression was seen in 9/38 (24%) patients. In 4 cases (44%) malignant progression was histologically confirmed. There were 8/15 (53%) patients showing tumor progression after a subtotal removal, but only one tumor recurred after a complete resection. One patient eventually suffered from a spinal metastasis.

Conclusions: In adults, piloA often grow in the temporal and parietal lobes. Chronic epilepsy is not rare. Anaplastic/malignant and atypical piloA are encountered surprisingly often. Malignant progression is frequently seen after a subtotal resection. piloA in adult patients seem to differ from their pediatric counterparts. These tumors should be resected aggressively, whenever possible.