Fig. 2From: Paraganglioma in the posterior mediastinum: a case reporta The resected mass had a dark brown to gray surface and measured 6.5 × 4.0 × 3.0 cm (47.5 g). b On histologic examination of the hematoxylin and eosin stained specimen (magnification, 100 ×), polygonal tumor cells are observed to be arranged in a nested pattern (Zellballen structure). c Positive immunohistochemical staining for synaptophysin in the tumor cells (magnification, 200 ×). d Positive immunohistochemical staining for S-100 protein in the sustentacular cells (magnification, 200 ×). e Negative immunohistochemical staining for cytokeratins (magnification, 200 ×). f The positive rate of Ki-67 proliferation index was 1% (magnification, 200 ×)Back to article page