Author/Editor		Gelpi, Ellen; Popović, Mara; Preusser, Matthias; Budka, Herbert; Hainfellner, Johannes
Title		Pleomorphic xanthoastrocytoma with anaplastic features presenting without GFAP immunoreactivity: implications for differential diagnosis
Type		članek
Source		Neuropathol Appl Neurobiol
Vol. and No.		Letnik 25
Publication year		2005
Volume		str. 241-6
Language		eng
Abstract		Pleomorphic xanthoastrocytoma (PXA) is an uncommon, usnally low-grade, astrocytic tumor. Characteristic histological features include tumor cell pleomorphism and lipidization of tumor cells. Albeit prognosis in PXA is generally good, cases with histological signs of anaplasia have been observed. In these cases, the differential diagnosis needs to exclude other malignancies, for example, glioblastoma or malignant fibrous histiocytuma. Immunocytochemical detection of GFAP may support exclusion of non-glial neoplasms resembling PXA. However, GFAP expression in PXA may be faint or focal, although complete lack of GFAP has not been described. A 43-year-old woman was operated on for a left occipital parasagital tumor attached to the dura. Histopathology showed a pleomorphic tumor with moderate mitotic activity and necrosis, lack of GFAP immunoreactivity and ultrastructural detection of premelanosome-like structures. These fealures led to the tentative diagnosis of amelanotic melanoma, and the patient was irradiated. Three years later she had local tumor recurrence and underwent another operation. The recurrent tumor showed similar plain histology as the first specimen. In contrast, anti-GFAP immunoreactivity was now detectable in pleomorphic tumor cells. Anti-GFAP staining of the first biopsy was repeated using monoclonal and polyclonal antibodies in combination with prolonged tissue pretreatment. Focal GFAP staining of tumor cells was now achieved. We conclude that nonstandard GFAP staining protocols may enhance sensitivity and thus lead to detection of a low level of GFAP expression in tumor specimens, in which PXA is considered in the differential diagnosis. This may avoid misleading diagnostic considerations that impact on postoperative patient management.
Descriptors		ASTROCYTOMA BRAIN NEOPLASMS GLIAL FIBRILLARY ACIDIC PROTEIN TUMOR MARKERS, BIOLOGICAL NEOPLASM RECURRENCE, LOCAL ADULT DIAGNOSIS, DIFFERENTIAL IMMUNOHISTOCHEMISTRY MELANOMA MICROSCOPY, CONFOCAL MICROSCOPY, ELECTRON