Diagnostic utility of IDH1- and p53-mutation analysis in secondary gliosarcoma.

We report on a 47-year-old woman in whom an anaplastic astrocytoma was resected in 2006. Postoperative radiation had to be interrupted because of a wound infection necessitating explantation of the infected bone flap and implantation of a titanium mesh. Subsequently, radiation therapy was completed and temozolomide was administered for 45 cycles. In the beginning of 2010 a new contrast enhancing mass was seen in the former tumor region. The mass was subtotally excised and showed no histomorphological similarity to the first lesion but represented a highly pleomorphic and mainly sarcomatoid differentiated malignant tumor. The lack of expression of GFAP or MAP-2 raised the question of a secondary malignancy, however, molecular genetic analysis of IDH1 and p53 revealed the same mutations in the anaplastic astrocytoma from 2006 as in the sarcomatoid tumor operated in 2010. Furthermore, accumulation of mutated IDH1 and TP53 protein could be demonstrated immunohistochemically. Thus, the second tumor represented the rare instance of recurrence of an anaplastic astrocytoma as a secondary gliosarcoma and a second malignant neoplasm was ruled out. The postoperative therapy and the inflammation might have contributed to the severe change in morphological phenotype of the glioma.