DOI 10.5414/NP300564

Clinical Neuropathology, Volume 32 - May/June (159 - 164)

Adult with cerebellar anaplastic pilocytic astrocytoma associated with BRAF V600E mutation and p16 loss

Yee Hui Yeo1, Nicholas P. Byrne2, George J. Counelis3, Arie Perry4
1 Department of Medicine, National Defense Medical Center, Taipei, Taiwan, R.O.C., 2 Contra Costa Pathology Associates, 3 Diablo Neurosurgical Medical Group, Inc., John Muir Medical Center, Walnut Creek, 4 Departments of Pathology, Neurological Surgery, University of California San Francisco, San Francisco, CA, USA

Abstract

Pilocytic astrocytoma (PA) is the most common pediatric tumor, with the vast majority being benign (WHO Grade I). Herein, we present a rare sporadic (not radiation- or NF1-associated) anaplastic PA arising from the cerebellum of an adult patient. The diagnosis was based on the coexistence of classic PA and more cellular foci, associated with both tumor necrosis and up to 27 mitoses per 10 high power fields. Based on these features, the tumor was felt to be equivalent in biological behavior to that of a WHO Grade III astrocytoma. Additional genetic studies revealed the presence of a BRAF V600E mutation. In comparison to the foci of classic PA, the malignant component showed increased p53 protein expression, decreased p16 protein expression, and hemizygous p16 gene deletion by FISH analysis. This case provides additional support for the concept of anaplastic transformation in PA and further elucidates the possible molecular pathways associated with malignant progression.

Author Details

Authors

  • Yee Hui Yeo1
  • Nicholas P. Byrne2
  • George J. Counelis3
  • Arie Perry4

Departments

  • 1 Department of Medicine, National Defense Medical Center, Taipei, Taiwan, R.O.C.,
  • 2 Contra Costa Pathology Associates,
  • 3 Diablo Neurosurgical Medical Group, Inc., John Muir Medical Center, Walnut Creek,
  • 4 Departments of Pathology, Neurological Surgery, University of California San Francisco, San Francisco, CA, USA

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