[Clinicopathologic study of pleomorphic xanthoastrocytoma of brain]

To study the clinicopathologic features, treatment response and prognosis of pleomorphic xanthoastrocytoma (PXA).

Amongst a total of 6 287 patients with central nervous system tumors encountered in Nanjing General Hospital of PLA during the period from 1980 to 2004, 15 cases of PXA were found. Two additional cases of PXA were also retrieved from the authors' consultation files. The clinicopathologic features of the 17 cases were studied. Follow-up information was available in 10 patients.

The age of the patients ranged from 12 to 55 years (mean = 30.8 years). The male-to-female ratio was 6:11. Commonest clinical symptoms included seizures, headaches and dizziness. The tumors in 16 patients were located in the superficial cerebral cortex (94.1%). Seven cases (41.2%) involved the temporal lobe. The size of the tumors varied from 2 to 7 cm (mean = 4.3 cm). Cystic degeneration was noted in 9 cases. For those in-house cases, total tumor excision was performed in 12 patients and subtotal tumor excision was performed in 3 patients. Amongst the 10 patients with follow-up information available, 8 were alive. The post-operative survival ranged from 10 months to more than 13 years (mean survival = 6 years). Classic histopathologic features included an admixture of mononuclear cells, bizarre multinucleated giant cells, spindled cells and lipid-rich vacuolated cells. The tumor cells were associated with abundant lymphocytes and reticulin fibers. They showed little tumor necrosis or mitotic activity. Immunohistochemical study demonstrated diffuse positive staining for glial fibrillary acidic protein, vimentin and S-100 protein. Seventy-seven percent of the cases also showed positive staining for CD34. One case had anaplastic transformation, with increased mitotic activity (mitotic count >or= 5 per 10 high power fields). The tumor cells infiltrated the underlying cerebral cortex with extension into perivascular spaces in 2 cases. Radiologic examination revealed tumor recurrence with diffuse leptomeningeal spread in 1 case.

PXA is low-grade glial tumor, corresponding to WHO grade II. Cases with typical pathologic features and total tumor excision carry favorable prognosis. Local recurrence or anaplastic transformation may occur in rare examples. Histologically, PXA can be mistaken as WHO grade IV giant cell glioblastoma, as both entities possess tumor giant cells. PXA however harbors lipiodized astrocytes and lacks coagulative tumor necrosis and high mitotic activity. Frequent expression of CD34 in PXA is also helpful in differential diagnosis.