PMC2253502_01
Gross photograph showing cut surface of right lobe of thyroid demonstrating a well circumscribed black colored nodule, (1a); photomicrograph shows encapsulated nodule compressing adjacent normal thyroid (1b, H&E, x100); caught up normal thyroid follicles in the tumor (1c, H&E, x200); higher magnification demonstrating plasmacytoid appearance of tumor cells (1d, H&E, x200); tumor cells containing brownish black pigment and focal areas of spindling (1e, H&E, x200); high magnification shows tumor cells laden with melanin (1f, H&E, x400)
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F1
Cut section of nodule was soft homogeneously black in color with grey white foci (Fig 1a). Morgagni 268, Holland). Microscopic examination showed a cellular tumor arranged in solid sheets, nests and trabecular pattern with few residual normal thyroid follicles (Fig 1b-f).
Photomicrographs showing tumor cells to be immunopositive for chromogranin A, synaptophysin, CEA, Calcitonin, HMB-45, and pan-CK (a-f, x200 each).
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F2
Tumor cells showed diffuse immunopositivity for calcitonin, HMB-45, carcinoembryonic antigen, synaptophysin, chromogranin, vimentin and epithelial membrane antigen but focal paranuclear dot-like positivity for cytokeratin (Fig 2a-f), and were negative for thyroglobulin, S-100, melan-A and TTF (Table 2).
Electronmicrographs showing oval to spindle shaped cells with prominent nucleoli (a, x2250 original magnification) packed with compound melanosomes and premelanosomes (b, x6250); higher magnification of premelanosomes demonstrating internal structure (c, x8250) and electron dense neurosecretory granules (d, x6250).
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PMC2253502_01_1746-1596-3-2-3.jpg
F3
Electron microscopy revealed abundant compound melanosomes, premelanosomes in various stages of melanogenesis and sparse membrane bound dense core neurosecretory granules measuring 50-200 nm along with intermediate filaments (Fig 3).