Primary Cerebellar Pilocytic Astrocytoma With Anaplastic Features in a Patient With Neurofibromatosis Type 1

—Case Report—

抄録

A 70-year-old woman with neurofibromatosis type 1 (NF-1) presented with a primary cerebellar pilocytic astrocytoma (PA) with anaplastic features manifesting as worsening headache and ataxia. Magnetic resonance (MR) imaging on admission showed a diffusely enhanced solid mass in the left cerebellar hemisphere, although MR imaging showed no abnormalities 2 years before admission. Histological examination after gross total removal of the tumor exhibited a biphasic pattern with marked Rosenthal fibers, together with some malignant features including frequent mitoses and invasive growth pattern. The final diagnosis was PA with anaplastic features. Previous PA cases with mitotic activity and endothelial proliferation, and/or palisading necrosis have been classified as anaplastic PA (or PA with anaplastic features). In the present case, the tumor histology corresponded to this designation. The present case indicates that PAs with anaplastic features can occur in patients with NF-1.