PLEOMORPHIC XANTHOASTROCYTOMA - DNA FLOW-CYTOMETRY AND OUTCOME ANALYSIS OF 12 PATIENTS

BACKGROUND. Pleomorphic xanthoastrocytoma (PXA) is an astrocytic tumor occurring primarily in childhood and adolescence with some malignant histologic features but a relatively slow clinical course. However, so me tumors progress more rapidly and can undergo malignant degeneration . The authors attempted to determine whether various histologic featur es or tumor cell proliferative indices might help identify lesions at risk for early progression and distinguish PXAs from malignant gliomas . METHODS. In a retrospective study of 12 patients with PXA, the tumor 's histologic features and DNA flow cytometric parameters were compare d with their clinical course. DNA now cytometry values for the S-and G Z-phase of the PXAs also were compared with control group samples of m alignant and low grade astrocytomas. RESULTS. Of the 12 tumors at init ial diagnosis, 5 were considered typical PXAs whereas 7 had some atypi cal features (4 with paucity of reticulin fibers, 1 with focal necrosi s, and 2 with both atypical reticulin and focal necrosis). During the follow-up period (range, 3.75-11 years; mean, 6.8 years), 2 patients h ad recurrences; 1 atypical reticulin PXA progressed to glioblastoma af ter 6.5 years and the 1 tumor with focal necrosis recurred at 6 months and again at 2 years with typical histologic features. DNA flow cytom etry parameters of the typical PXA group were similar to Values for ma lignant astrocytoma and significantly higher than values for control s pecimens of low grade astrocytomas. There were no distinctive DNA now cytometric features that could distinguish this last tumor from others with a more benign clinical course. CONCLUSIONS. Measurements of the S-phase and GZ-phase obtained from DNA flow cytometry and atypical his tologic features cannot reliably identify PXA patients at risk for ear ly progression and overall are significantly higher than values obtain ed for low grade gliomas. Therefore, frequent (i.e., two to three time s per year) postoperative clinical and radiologic examinations are nec essary to judge the appropriateness of adjuvant therapy in patients wi th PXA. The paradox of slow growth but DNA flow cytometry consistent w ith aggressive malignant lesions may represent a cell-cycle arrest mec hanism in these lesions that could be verified in subsequent studies. (C) 1997 American Cancer Society.