Brain Pathology Case of the Month - December 2015

Contributed by Wai Kiu Tang1, Ho Keung Ng2,3, Danny Tat-Ming Chan3, Xian Lun Zhu3, Wai-Sang Poon3
Departments of Diagnostic Imaging and Interventional Radiology1, Anatomical and Cellular Pathology2, CUHK Otto Wong Brain Tumour Centre,
    Department of Surgery3,The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China


A right-handed 14 year-old boy was admitted for a first unprovoked generalized tonic clonic seizure, which was preceded by ongoing headache and nausea for a few days. His parents also noted a sharp decline in his academic performance in recent months. Physical examination was unremarkable except for the presence of right homonymous superior quadrantanopia. Psychological assessment revealed impairment in his verbal memory and learning. Blood results and EEG were unremarkable. Imaging of the brain by CT showed a left temporal mass with calcifications and hemorrhage (Figure 1), and MRI revealed a large avidly contrast-enhancing left temporal mass measuring 4 x 5 x 4cm with evidence of recent hemorrhage (Figures 2 and 3). There were foci of edema and mass effects causing compression of the left temporal horn with adjacent sulcal effacement (Figure 4). He underwent gross total tumor resection under ultrasound guidance via a left temporal craniotomy.


Microscopic examination of the tumor specimen showed many fibrotic areas with heavy calcification on low power field (Figure 5). The tumor itself appeared to consist of roughly two parts. In one, a myxoid picture was evident with cords of round tumor cells arranged in a myxoid sarcomatous appearance (Figure 6), which gradually merged into the fibrotic region with calcification. In the other part of the tumor, many large round cells were seen with large eccentrically located nuclei, prominent nucleoli and voluminous cytoplasm (Figure 7). Mitotic figures were brisk and Ki67 is 80%. Tumor cells were focally positive by immunostaining for epithelial membrane antigen (EMA) (Figure 8) but negative for GFAP, olig-2, and INI-1 (Figure 9), the latter with repeated staining. What is your diagnosis?


International Society of Neuropathology