Multicentric Glioma Develops via a Mutant IDH1-Independent Pathway: Immunohistochemical Study of Multicentric Glioma.

Multicentric gliomas are very rare. Due to differences in their tumor types they remain enigmatic. We focused on the pathogenesis of multicentric gliomas and compared their immunoprofile with that of solitary gliomas. This retrospective study included 6 males and 8 females with multicentric glioma (8 glioblastomas, 2 anaplastic astrocytomas, 4 diffuse astrocytomas). Their age ranged from 27 to 75 years and all were treated between 2004 and June 2015. The expression of mutant isocitrate dehydrogenase 1 (IDH1), α-thalassemia X-linked intellectual disability (ATRX), p53, phosphatase and tensin homolog (PTEN), and epidermal growth factor receptor (EGFR) was examined immunohistochemically; for 1p19q analysis we used fluorescence in situ hybridization (FISH). In all patients, immunohistochemical staining was negative for mutant IDH1 and cytoplasmic PTEN; only 1 patient (7.1%) manifested nuclear PTEN positivity. FISH for 1p19q codeletion was negative in all 9 examined samples; 5 of 14 specimens (35.7%) were p53-positive, 9 (64.3%) were EGFR-positive, and 4 (28.6%) were ATRX-negative. The MIB-1 labeling index was 0.9-15.6% for grades II and III, and ranged between 17.3 and 52.4% for glioblastoma. Our results suggest that the pathogenesis of multicentric gliomas is different from the mutant IDH1-R132H pathogenesis of lower-grade glioma and secondary glioblastomas. More studies are needed to confirm the molecular mechanisms underlying the pathogenesis of multicentric glioma.

Benign fibrous histiocytoma arising at the temporal bone of an infant--case report and review of the literature.

PURPOSE: We report a very rare case of a fast-growing benign fibrous histiocytoma at the temporal bone. METHODS: A 1-year-old girl was referred for investigation of a right temporal mass that increased during 2-week observation. Imaging studies showed a lytic, loculated skull tumor at the left temporal bone. On magnetic resonance imaging scans, the tumor was isointense on T1- and relatively high-intense on T2-weighted images. The tumor was mostly homogeneously enhanced by gadolinium. On diffusion-weighted images, it was iso- to relatively low-intense; perfusion-weighted images revealed low perfusion. RESULTS: Complete macroscopic resection of the tumor was performed. Immunohistochemical analysis showed that the tumor was positive for CD68 and α-smooth muscle actin and negative for CD1a and CD34; the MIB-1 labeling index was 4 %. A diagnosis of primary benign fibrous histiocytoma of the skull was made. At 6-month follow-up, there were no clinical or radiological signs of tumor recurrence and/or metastasis. CONCLUSIONS: We review the clinical, radiological, and immunohistochemical characteristics of benign fibrous histiocytoma at the skull.