Pilomyxoid astrocytoma with high proliferation index
A 12-years-old male presented with focal seizures, headache and vomiting of 10 days duration. On clinical examination there were no neurological deficits or papilledema. Computed tomogram (CT) scan of the brain showed a solid-cystic lesion in the left temporal lobe, which was hypo- to hyperdense with peripheral contrast enhancement []. Gross total resection of the tumor was done and sent for histopathological examination. Immediate post-operative period and further recovery was uneventful.\nMicroscopic examination showed a cellular tumor, composed of monomorphous, bipolar cells arranged in dyscohesive sheeting pattern [], interspersed with microcytic spaces and abundant myxoid matrix []. The tumor cells were small to medium-sized, with scant cytoplasm and bipolar, short cytoplasmic processes arranged in an angiocentric fashion, forming pseudorosettes []. Brisk mitotic activity and foci of necrosis [] was seen. However, no Rosenthal fibers or eosinophilic granular bodies were noted. Immunohistochemical studies showed strong glial fibrillary acid protein (GFAP) positivity [ inset], p53 positive in occasional tumor cell nuclei [] and Ki-67 labeling index varied from 30-40%% [] in different areas of the tumor. Tumor cells were immunonegative for epithelial membrane antigen (EMA) [ inset].\nThe patient had received 50Gy radiation with concurrent temozolamide (TMZ) over a period of 5 weeks at 75 mg/m2. The patient presented with recurrence after two years. Histological examination of the repeat gross total excision specimen showed radiation-induced geographic necrosis [Figure and ], ghost outlines of angiocentric tumor pattern [], with preserved tumor islands, retained angiocentricity and myxoid matrix [ inset], and Ki-67 labeling index of 40-50% []. The patient had received 50 Gy radiation with concurrent TMZ over a period of 5 weeks at 75 mg/m2, followed adjuvant TMZ at 150 mg/m2 from day 1 to day 5, cycles repeated every 4 weeks.