Brain Pathology Case of the Month - December 2010

Contributed by Feng Wan1, Ping Zhang1, Yuanli Zhu2, Kelan Wu2, Yang Gua3, Changshu Ke2, Ting Lei1
1 Department of Neurosurgery, 2 Department of Pathology, Tongji Hospital, Huazhong University of Science & Technology, Wuhan, China
3 Department of Ultra-structural Pathology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China


A 47 year-old man presented with left extremity weakness for 1 year, which had worsened significantly over the past 40 days. 23 years ago he suffered head trauma with loss of consciousness for 30 minutes and was diagnosed with a concussion. Two weeks later he had his first generalized seizure, and continued to have about one seizure per week. His seizures were not well-controlled on phenytoin. Fifteen years ago, the patient underwent brain CT scan, revealing right frontal encephalomalacia (Figure 3). Epilepsy surgery was performed and silver clips were deployed for hemostasis. Following the surgery and change of medications to carbamazepine he continued to suffer seizures about one or twice a month. At this current presentation for left extremity weakness, the neurological examination discovered decreased muscle strength of the left side. CT scan revealed a huge hypodense lesion in the right frontal lobe with remarkable mass effect (Figure 1), but without distinct contrast-enhancement (Figure 2). Hyperdense foci could be seen within the mass, which were ascertained to be the silver clips used in his surgery. MRI scan could not be performed due to these clips. A right frontal craniotomy was performed and a large tumor was removed and submitted for pathology.


Grossly, the tumor was about 8cm in diameter, hard in texture, surrounded by gliosis with partial infiltration into the cerebral cortex and invasion of the overlying bone flap. Upon sectioning, the silver clips were found within the compact tumor parenchyma, surrounded by a halo of dark-stained tissue (0.5-1cm in diameter). Histologically, the tumor was composed of spindle-shaped cells arranged in fascicles with discernible collagenous matrix in between (Figures 4 and 5); The fusiform and tapered nuclei were moderately hyperchromatic and exhibited pleomorphism; Mitotic activity was common but atypical mitoses were rarely seen; There were occasionally bizarre and multi-nucleated tumor cells; The tumor invaded the brain with an ill-defined border, and reactive gliosis at the edges. The tumor cells revealed a strong positive reaction for a-SMA (Figure 6), but negative for vimentin, pan-cytokeratin, EMA (Epithelial Membrane Antigen) and CD34. Ki-67 labeling index was <30%. Ultrastructurally, tumor cells contained elliptical or irregular nuclei with distinct nucleoli. There were large amounts of dilated rough endoplasmic reticulum (rER) and thin myofilaments associated with local dense bodies in the cytoplasm (Figure 7).


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