Pleomorphic xanthoastrocytomas: Immunohistochemistry, grading and clinico-pathologic correlations. An analysis of 34 cases from a single institute

Pleomorphic xanthoastrocytomas (PXAs) are characterized as a well-delineate d tumor entity with clear peculiarities in clinico-radiological picture, pa thological appearance and biological behavior. Usually the PXAs are associa ted with relatively good prognosis. Nevertheless, up to 35% of patients die following one and more recurrence with or without tumor malignant transfor mation. Till now, there is no agreement on what histopathological features constitute to objective and reliable signs of PXAs malignancy and clinical outcome. Thirty-four PXAs were subdivided on three subsets: typical (Grade I) - tumors without mitoses per 20 high power fields, proliferating (Grade II) - tumors with mitoses but without necroses, and malignant (Grade III) - tumors with elevated mitotic index and necrotic foci. Also, immunohistoche mical investigation with various tumor-associated antigens was performed. A ll PXAs subtypes showed differences in clinical outcomes. There were no rec urrences and death among the tumors Grade I. Five out of 14 (36%) Grade II PXAs have recurred and one of them died. All 5 patients with PXAs Grade III have rapidly recurred and four of them died. Immunohistochemical variables , such as Ki-S1, p27/Kip1, vascular endothelial growth factor expression, p 53 immunoreactivity and apoptotic index also exhibited significant differen ces among the three PXAs grades. The progression-free survival was signific antly reduced for PXAs grade and presence of mitoses, whereas overall survi val was reduced for mitotic index greater than or equal to 3 and presence o f necroses. No one from immunohistochemical variables reached significant v alue. In summary, the three-tiered PXAs subdivision proposed by us is carry ing some element of rationality but, undoubtedly, requires further prospect ive studies.