Brain Pathology Case of the Month - December 2008



Pleomorphic Xanthoastrocytomas (PXA) account for less than 1% of astrocytic neoplasms (10). PXAs most commonly affect those in their first and second decades, and typically present with seizures. More than 98% of PXAs are found supratentorially (1).

Imaging usually reveals the tumor mass and associated cyst. Tumors are most often superficial with meningeal attachment (10).

Typical histologic features include cytoplasmic and nuclear pleomorphism, variable xanthomatous change of the neoplastic cells, reticulin fibers surrounding cells, eosinophilic granular bodies and collections of perivascular lymphocytes. Mitotic figures are usually absent or sparse and Ki-67 labelling is <1% (10). PXAs are considered to be of glial origin with tumor cells expressing GFAP and S-100 protein. PXAs frequently harbor select cells which variably express neuronal markers including synaptophysin, neurofilament, NeuN, MAP2, and class III B tubulin (2).

PXAs are a WHO grade II neoplasm with a generally favorable prognosis; survival is reported as 81% at 5 years (10). Malignant progression is, however, reported to occur in up to 20% of cases (6).

PXAs are uncommon but well known tumors. The present case was of added interest for its atypical location and for being one of only three pigmented examples reported. The two previous reported cases of pigmented PXA were suprasellar and medial temporal in location, presenting with a visual field deficit and seizures, respectively (5,7).

The present case was typical with respect to histological, immunohistochemical and ultrastructural features. Although the tumor cells expressed abundant GFAP, select cells expressed neuronal markers synaptophysin and neurofilament. The significance of this seemingly ambivalent bi-phenotypic expression pattern is unknown although some have suggested this as evidence that PXAs may be neuroglial in nature (2,3).

The feature of particular interest in the present case was the presence of melanin. Examples of pigmented primary tumors are well documented with pigments including neuromelanin, melanin and lipofuscin. Five melanotic astrocytic tumors have been previously reported. Of these five tumors; two were PXAs, one had PXA-like features, one was a ganglioglioma with PXA as the astrocytic component and one was a pilocytic astrocytoma (4,5,7,8,9). In the present case, Masson-Fontana preparations and ultrastructural examination confirmed the pigment to be melanosomal melanin. Of the five previously reported melanotic tumors, all but the pilocytic astrocytoma, were also found to contain melanosomal melanin as their pigment (5,7).

The present case is the third pigmented PXA to be reported, adding to a small collection of melanotic gliomas. While melanin production in gliomas is a curious finding, its prognostic significance is uncertain. In a twelve year follow up of one pigmented PXA there was no recurrence (5). In the present case there is no evidence of recurrence on MRI one year post-operatively.


  1. Giannini C, Paulus W, Louis DN, Liberski P (2000) Pleomorphic xanthoastrocytoma. In: Pathology and Genetics of Tumors of the Nervous System, Kleihues P, Cavanee WK (eds.), pp. 22-24, IARC Press: Lyon.
  2. Giannini C, Scheithauer BW, Lopes MB, Hirose T, Kros JM, VandenBerg SR (2002) Immunophenotype of pleomorphic xanthoastrocytoma. Am J Surg Pathol 26:479-485.
  3. Im SH, Chung CK, Kim SK, Cho BK, Kim MK, Chi JG (2004) Pleomorphic xanthoastrocytoma: A developmental glioneuronal tumor with prominent glioproliferative changes. J Neurooncol 66:17-27.
  4. Kanzawa T, Takahashi H, Hayano M, Mori S, Shimbo Y, Kitazawa T (1997) Melanotic cerebral astrocytoma: Case report and literature review. Acta Neuropathol 93:200-204.
  5. Krossnes BK, Mella O, Wester K, Mork SJ (2004) Pigmented astrocytoma with suprasellar location: Case report and literature review. Acta Neuropathol 108:461-466.
  6. Marton E, Feletti A, Orvieto E, Longatti P (2007) Malignant progression in pleomorphic xanthoastrocytoma: Personal experience and review of the literature. J Neurol Sci 252:144-153.
  7. Sharma MC, Arora R, Khanna N, Singh VP, Sarkar C (2001) Pigmented pleomorphic xanthoastrocytoma: Report of a rare case with review of the literature. Arch Pathol Lab Med 125:808-811.
  8. Soffer D, Lach B, Constantini S (1992) Melanotic cerebral ganglioglioma: Evidence for melanogenesis in neoplastic astrocytes. Acta Neuropathol 83:315-323.
  9. Vajtai I, Yonekawa Y, Schauble B, Paulus W (1996) Melanotic astrocytoma. Acta Neuropathol 91:549-553.
  10. Walker DG, Kaye AH (2003) Low grade glial neoplasms. J Clin Neurosci 10:1-13.

Contributed by Erin M. Chapman, Adrianna Ranger, MD, Donald H. Lee, MD, Robert R. Hammond, MD

International Society of Neuropathology