PMC3278378_01
Enhanced chest computed tomography shows a heterogeneous 9.0 x 7.5 cm mass arising in the anterior mediastinum.
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F1
The mass showed a heterogeneous densitometric characteristic accompanied with areas of necrosis after contrast enhancement (Figure 1).
The oval-shaped tumor had a smooth surface, and its cut surface was homogenously solid with a yellowish-white color. The tumor was partially involved in the lung parenchyma (arrowhead).
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F2
The oval-shaped tumor had a smooth surface, and its cut surface was homogenously solid and yellow-white in color (Figure 2).
Numerous typical whorl formations (A) and small cells with a high nuclear/cytoplasmic ratio (B) were observed in the tumor. Spontaneous necrosis was occasionally seen (C). The tumor was partially involved in the adjacent pulmonary parenchyma (D). There were some mitotic figures, and the Ki-67/MIB-1 labeling index was approximately 7% in relatively higher positive-rate fields (E). Marked immunoreactivity for epithelial membrane antigen (EMA) was seen (F).
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F3
In some areas, many typical whorl formations for fibrous meningioma were observed (Figure 3A). There were several foci of small cells with a high nuclear/cytoplasmic ratio (Figure 3B). Spontaneous and zonal necroses were occasionally seen (Figure 3C). In addition, the tumor involved adjacent pulmonary parenchyma (Figure 3D). The mitotic index was four per 10 high-power fields (hpf) at the areas where the mitotic figures were most frequently observed, and the Ki-67/MIB-1 labeling index was approximately 7% in relatively higher positive-rate fields (Figure 3E).