PMC5398289_01
(A), (B) Tumor cells without pigment. (C), (D) Tumor cells with pigment in the cytoplasm.
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The first component, the majority of the mass, was composed of solid sheets and clusters of cohesive epithelial cells, with no pigment observed in the cytoplasm (Figure 1A, B). The second component comprised cells covered by pigment, with the intercellular substance and structure unclear (Figure 1C, D). A large quantity of pigments were within the stroma (Figure 1C).
Synaptophysin diffusely expressed in the tumor cells.
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Using immunohistochemistry, the tumor cells in the first component tested diffuse strong positive for synaptophysin (Syn) (Figure 2), but negative for chromogranin A (CgA), pan-cytokeratin, calcitonin and thyroglobulin.
(A), (B) Few cells were positive for HMB-45 and Melan A after the tissue was bleached by oxalic acid. (C) The stromal cells were positive for S-100 after the tissue was bleached by oxalic acid. (D) The tumor cells were negative for calcitonin. (E) The tumor cells were negative for thyroglobulin.
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Of the cells surrounding the tumor, few were positive for HMB-45 and Melan A after bleaching by oxalic acid (Figure 3A, B). The stromal cells were positive for S-100 (Figure 3C). The tumor cells were negative for calcitonin and thyroglobulin (Figure 3D, E).
(A) Electron micrograph showing granules of uniform electron density, membrane-limited, and 100 to 150 microm in diameter; most had halos or clear spaces between the granule and the surrounding limiting membrane. (B) Many round melanin bodies with greater electron density granules of uniform size were observed.
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Half of the chief cells had abundant cytoplasm with dispersed organelles and secretory granules (Figure 4); the other half had less cytoplasm and more closely approximated organelles and granules. The cytoplasm contained numerous mitochondria and many dense granules of the neurosecretory of endocrine type (Figure 4). A few had less cytoplasm and fewer organelles, and these also had many round melanin bodies with greater electron density granules of nonuniform size (Figure 4).