Cerebrospinal fluid cytologic findings of a pleomorphic xanthoastrocytoma: a case report.

Background: Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm with a relatively favorable prognosis. Characteristic histologic features include pleomorphic tumor cells and lipidized cells expressing glial fibrillary acidic protein (GFAP), corresponding to a World Health Organization grade 2 tumor. Cytologic features of PXA have been rarely described, only in squash specimens, but only 2 cases are reported in cerebrospinal fluid (CSF).

Case: A 45-year-old woman complained of severe headaches and diplopia. Computed tomography of the central nervous system revealed a supracallous periventricular tumor mass suggestive of either a lymphoma or a metastatic carcinoma. CSF revealed 18 cells/mm3 and contained numerous tumor cells highly pleomorphic in size and shape. Some atypical cells of moderate size were closely packed with well-defined cytoplasmic limits and a vacuolated appearance, suggesting an epithelial proliferation. On immunocytochemistry atypical cells were positive for GFAP, S100 protein and synaptophysin but were negative for pancytokeratins and epithelial membrane antigen. A primitive glial proliferation was found, and paraffin-embedded tumor tissue obtained by biopsy confirmed the diagnosis of anaplastic PXA.

Conclusion: Observation of PXA in CSF might cause some differential diagnosis problems, especially with a metastatic epithelial malignancy. We present a case of anaplastic PXA with an unusual periventricular location and its cytologic features in CSF.